US 6,271,015 B1Grant
Fatty-acid amide hydrolase
Issue Date:2001-08-07
•6 Claims
•26 Drawing Sheets
Abstract
The soporific activity of cis-9,10-octadecenoamide and other soporific fatty acid primary(amides is neutralized by hydrolysis in the presence of fatty-acid amide hydrolase (FAAH). Hydrolysis of cis-9,10-octadecenoamide by FAAH leads to the formation of oleic acid, a compound without soporific activity. FAAH has be isolated and the gene encoding FAAH has been cloned, sequenced, and used to express recombinant FAAH. Inhibitors of FAAH are disclosed to block the hydrolase activity.
Metadata
Assignee
- The Scripps Research Institute
Inventors
- Norton B. Gilula
- Benjamin F. Cravatt
- Richard A. Lerner
Application Information
Application Number:US 08/743,168
Filing Date:1996-11-04
Priority Date:1995-06-12
Art Unit:7
Classifications
IPC:
C12N 980
Field of Search:
435227435228435134435129435 771532 62536 919
Patent Drawings (26 sheets)
Description
Cross Reference to Related Applications
[0002] This application is a continuation-in-part of U.S. patent application Ser. No. 08/489,535, filed on Jun. 12, 1995, now abandoned, the disclosures of which is incorporated herein by reference.
Technical
[0004] The invention relates to an enzyme which catalyzes a hydrolytic conversion between soporific fatty acid primary amides and their corresponding fatty acids and is designated a fatty-acid amide hydrolase (FAAH), to methods for enzymatically catalyzing such conversions, and to methods for inhibiting the enzymatic catalysis of such conversions. More particularly, the invention relates to FAAH protein, in either isolated or recombinant form, and to its use and inhibition.
Background
[0005] Sleep is a natural, periodic behavioral state during which the body rests itself and its physiological powers are restored. It is characterized by a loss of reactivity to the environment. During sleep, certain physiological processes of both the body and the brain function differently than they do during alert wakefulness. Normal sleep consists of at least two quite different behavioral states: synchronized sleep, during which the electroencephalogram consists of slow waves of high amplitude, and desynchronized sleep (DS) or activated sleep characterized by rapid eye movements (REM sleep), in which the electroencephalogram pattern is characterized by waves of high frequency and low amplitude. Synchronized sleep is further characterized by slow and regular respiration, by relatively constant heart rate and blood pressure, and by a predominance of delta waves. Synchronized sleep usually consists of four stages, followed by a period of activated sleep. Each cycle lasts between 80 and 120 minutes. In contrast, desynchronized sleep is further characterized by irregular heart rate and respiration, periods of involuntary muscular jerks and movements, and a higher threshold for arousal. Periods of desynchronized sleep last from 5-20 minutes and occur at about 90 minute intervals during a normal night's sleep.
[0006] Sleep disorders include sleep deprivation and paroxysmal sleep, i.e., narcolepsy. There has been no known pharmacological method for promoting or inhibiting the initiation of sleep or for maintaining the sleeping or waking state.
[0007] Cerebrospinal fluid (liquor cerebrosinalis) is a clear, colorless fluid that circulates within the four ventricles of the brain and the subarachnoid spaces surrounding the brain and spinal cord Cerebrospinal fluid originates as an ultrafiltrate of the blood secreted by the choroid plexus in the lateral third and fourth ventricles. Cerebrospinal fluid is also sometimes called neurolymph. After passing through the four ventricles and the subarachnoid spaces, cerebrospinal fluid is largely resorbetd into the venous system via the arachnoid villi. Cerebrospinal fluid serves as a medium for the removal of catabolites, excretions, and waste materials from the tissues bathed by it. To date, no factor derived from cerebrospinal fluid has been reported to correlate with sleep deprivation. What is needed is a method for analyzing cerebrospinal fluid for identifying a biochemical factor generated by subject that correlates with sleep deprivation.
[0008] Since the seminal discovery of prostaglandins, there has been increasing recognition of the role of fatty acids and their derivatives in important physiological processes, e.g., B. Samuelsson, Les Prix Nobel1982, pp. 153-174.
[0009] Cis-9,10-Octadecenoamide has been isolated from the cerebrospinal fluid of sleep-deprived cats and has been shown to exhibit sleep-inducing properties when injected into rats. Other fatty acid primary amides in addition to cis-9,10-octadecenoamide were identified as natural constituents of the cerebrospinal fluid of cat, rat, and man, indicating that these compounds compose a distinct family of brain lipids. Together, these results teach that fatty acid primary amides represent a new class of biological signalling molecules that can be employed for inducing subjects to sleep. Preferrers fatty acid primary amides include an alkyl chain having an unsaturation and are represented by the following formula: NH2C (O) (CH2)(6≧n≦11)CH═CH(CH2)(8≧n≦5)CH3. Preferred soporific fatty acid primary amides have an unsaturation with a cis configuration within their alkyl chain. In addition to cis-9,10-octadecenoamide, other soporifically active fatty acid primary amides include cis-8,9-octadecenoamide, cis-11,12-octadecenoamide, and cis-13,14-docosenoamide.
[0010] Deutsch et al, Biochem. Pharmacol.,46:791 (1993) has identified an amidase activity which catalyzes both the hydrolysis and synthesis of arachidonylethanolamide (anandamide) from the membrane subcellular fractions taken from neuroblastoma, glioma cells and crude homogenates of rat brain tissues. The study detected the uptake and enzymatic breakdown of arachidonylethanolamide (anandamide) to arachidonic acid (and vice versa) from the homogenates of tissues from brain, liver, kidney and lung but not from rat heart and skeletal muscles.
[0011] The active membrane fraction which displayed this amidase activity was prepared by either homogenizing the desired cell line and subsequently subjecting the crude homogenate to density centrifugation or by taking the crude homogenates of rat brains and directly incubating them with anandamide.
[0012] The uptake and degradation of arachidonylethanolamide (anandamide) was assayed by incubation of [3H]-anandamide (NEN, NET-1073, 210 Ci/mmol) in the cell culture medium. It was found, by liquid scintillation counting of the aqueous and organic phases, that arachidonic acid and anaiidamide distributed in the organic phase. Thus, the organic extract of the cell medium was subsequently visualized using thin-layer chromatography, sprayed with a surfaces autoradiograph enhancer (EN3HANCE, Dupont) and exposed to X-ray film (Kodak X-OMAT AR) at −80° C.
[0013] The serine protease inhibitor, phenylmethylsulfonyl fluoride at 1.5 mM concentration completely inhibited the amidase activity. Other inhibitors tested had little or no effect on the activity and included aprotinin, benzamidine, leupeptin, chymostatin and pepstatin.
[0014] In a second manuscript, Deusch et. al. (J. Biol Chem.,1994, 269, 22937) reports the synthesis of several types of specific inhibitors of anandamide hydrolysis and their ability to inhibit anandamide breakdown in vitro. Four classes of compounds were synthesized and include fatty acyl ethanolamides, α-keto ethanolamides, α-keto ethyl esters and trifluoromethyl ketones. The most effective class of compounds were the trifluoromethyl ketones and α-keto esters. The least potent inhibitors were the α-keto amides and saturated analogs of anandamide.
[0015] As an example, when anandamide is incubated with neuroblastoma cells, it is rapidly hydrolyzed to arachidonate but in the presence of the inhibitor arachidonyl trifluoromethyl ketone, there is a 5 fold increase of anandamide levels. The study infers that polar carbonyls such as those found in trifluoromethyl ketones, may form stabilized hydrates that mimic the tetrahedral intermediates formed during the reaction between the nucleophilic residue and the carbonyl group of anandamide. Deutsch suggests that the nucleophilic residue may be the active site of a serine hydroxyl in the hydrolytic enzyme.
[0016] This enzyme is classified as an amidase (EC #3.5) where the enzyme acts on carbon nitrogen bonds other than peptide bonds. The amidase activity is inhibited by the serine protease inhibitor, PMSF and the action of trifluoromethyl ketone inhibitors (and others) directly affect the hydrolytic activity of the enzyme. Furthermore, Deutsch suggests that anandamide is cleaved by a mechanism that involves an active site serine hydroxyl group.
[0017] What is needed is an identification of enzymes within the brain tissue which catalyze the degradation of soporific compound found in the cerebrospinal, for mediating the soporific activity of these compounds. What is needed is an identification of inhibitors for inhibiting the activity of enzymes which degrade soporific compounds of the type found in cerebrospinal fluid.
Brief Summary of the Invention
[0018] An enzyme is disclosed herein which degrades soporific fatty acid primary amides, and is designated fatty-acid amide hydrolase, or FAAH. FAAH is one of the enzymes which mediates the activity of fatty acid primary amides, including soporific fatty acid primary amides.
[0019] As disclosed herein, FAAH is characterized by an enzymic activity for catalyzing a conversion cis-9,10-octadecenoamide to oleic acid, among other substrates, as shown in Scheme 1 below, and therefor was originally identified as cis-9,10-octadecenoamidase. However, it is now shown that FAAH has activity to hydrolyse a variety of fatty acid primary amides, and therefore the amidase originally referred to as cis-9,10-octadecenoamidase is more appropriately reffered to as FAAH.
[0020] One aspect of the invention is directed to a purified form of FAAH. FAAH can be purified by a variety of methods, including a chromatographic methodology. Preferred chromatographic methodologies include affinity chromatography, electric chromatography, gel filtration chromatography, ion exchange chromatography, and partition chromatography. In affinity chromatography, a solid phase adsorbent contains groups that bind particular proteins because they resemble ligands for which the proteins have a natural affinity. In a preferred mode, the solid phase adsorbent contains one or more FAAH inhibitors which bind the enzyme. In antibody affinity chromatography, a solid phase immunoabsorbent having antibodies with a bind specificity with respect to FAAH are employed. In electric chromatography or electrophoresis, the FAAH is separated from other molecules according to its molecular weight or isoelectric point. In gel filtration, also known as gel permeation, molecular sieve, and exclusion chromatography, the solid phase creates a stationary phase of gel solvent and a mobile phase of excluded solvent. The FAAH is separated according to its molecular size as it partitions between the stationary and mobile phases. The gel particles are selected to have a exclusion size in excess of FAAH. In ion exchange chromatography, a solid phase ion exchanger is employed for separating the FAAH from other molecules according to its partitioning between ionic and nonionic forces. In partition chromatography, immiscible fluids having a stationary and mobile phases are employed for separating the FAAH according to its partitioning between the two immiscible phases. Preferred chromatographic methodologies include DEAE chromatography, affinity chromatography on a solid phase having attached Hg groups derivatized with an inhibitor of FAAH such as a trifluoroketone.
[0021] In a preferred mode, a crude source of FAAH is purified in four steps. In the first step, a crude source of FAAH is purified by exchange chromatography using a DEAE chromatography column to form a first elution product. In the second step, the elution product from the first step is further purified by partitioning by with affinity chromatography to form a second elution product. In the third step, elution product from the second step is further purified by partitioning with Heparin affinity chromatography to form a third elution product. In the fourth step, the elution product from the third step is further purified by partitioning with an stationary phase derivatized with a trifluoroketone inhibitor of FAAH. The eluant from the fourth step form the purified form of FAAH. FAAH can be isolated from any of a variety of mammalian species, including rat, mouse or human, as described herein.
[0022] Fatty-acid amid hydrolase (FAAH) is characterized by inclusion of an amino acid sequence selected from a group consisting of:
[0023] Another aspect of the invention is directed to a method for catalyzing the hydrolysis of a fatty acid primary amide. In this hydrolysis method, the fatty acid primary amide is combined or contacted with a catalytic amount of purified form of FAAH. In a preferred mode, the fatty acid primary amide is of a type which includes an alkyl chain having an unsaturation or more particularly is represented by the following formula:
[0024] NH2C(O)(CH2)(6≧n≦11)CH═CH(CH2)(8≧n≦5)CH3,
[0025] More particularly, the unsaturation of the alkyl chain may have a cis configuration or may be identically cis-9,10-octadecenoamide, cis-8,9-octadecenoamide, cis-11,12-octadecenoamide, or cis-13,14-docosenoamide.
[0026] Another aspect of the invention is directed to a method for inhibiting an enzymatically catalyzed hydrolysis of fatty acid primary amides, such as cis-9,10-octadecenoamide, by FAAH. In this method, FAAH is combined or contacted with an inhibitor of FAAH. Preferred inhibitors include phenylmethylsulfonyl fluoride, HgCl2, and a trifluoroketone having the following structure:
[0027] Another aspect of the invention is directed to a method for ascertaining the inhibitory activity of a candidate inhibitor of FAAH. Thus, FAAH is admixed with a candidate FAAH inhibitor to assess inhibitory capacity in a screening method.
[0028] In a preferred method for determining inhibitory activity of a candidate FAAH inhibitor, the contemplated method comprises five steps. In the first step, a mixture “A” is formed by combining FAAH and cis-9, 10-octadecenoamide substrate under reaction conditions. In the second step, a mixture “B” is formed by combining the mixture “A” with the candidate inhibitor. In the third step, the conversion of cis-9,10-octadecenoamide substrate to a hydrolysis product within mixture “A” is quantified. In the fourth step, the conversion of cis-9,10-octadecenoamide substrate to hydrolysis product within mixture “B” is quantified. In the fifth step, the inhibitory activity of the candidate inhibitor is ascertained by comparing the quantifications of steps three and four.
[0029] Another aspect of the invention is directed to a trifluoroketone inhibitor of FAAH represented by following structure:
[0030] Another aspect of the invention is directed to one or more nucleotide sequences the encode part or all of FAAH. The complete nucleotide sequence that encodes human, mouse or rat FAAH are shown in SEQ ID Nos. 42, 39 or 35, respectively.
[0031] The partial nucleotide sequence of rat FAAH is represented as follows:
Brief Description of the Drawings
[0032] FIG. 1 illustrates the structures of natural agent, cis-9,10-octadecenoamide (1), related analogs (2-6). Compound 6 is the preferred structure for naturally occurring C22fatty acid amide.
[0033] FIG. 2 illustrates the determined partial amino acid sequence of the rat FAAH as described in Section B.4.
[0034] FIG. 3 illustrates a partial purification strategy involving isolation of a plasma membrane protein fraction from rat liver using 1) a sucrose gradient of the liver membrane followed by 2) a 100 mM sodium carbonate wash and 3) solubilization in trion-based buffer. The isolated liver plasma membrane is then purified by four consecutive chromatographic steps: 1) Ion exchane DEAE column, 2) Mercury inhibition column, 3) detergent exchange Heparin column followed by 4) an affinity column with a trifluoroketone inhibitor. The purified protein was determined to have a 20-30 fold enrichment of amidase activity from crude membrane protein fraction by visual comparison of the purified protein band intensity with the crude protein fraction. Estimated purified yield is 10-15% from crude liver plasma membrane protein.
[0035] FIG. 4 illustrates the affinity column purification strategy (step 4, FIG. 3) using a trifluoroketone inhibitor which is linked to a disulfide-derivatized solid support (pyridyl disulfide beads).
[0036] FIG. 5 illustrates the synthetic protocol for the synthesis of the trifluoroketone inhibitor and subsequent attachment of the inhibitor to the disulfide-derivatized solid support using pyridyl disulfide beads.
[0037] FIG. 6 represents an autoradiogram of a thin layer chromatography plate (SiO2, 55% ethyl acetate/hexanes) illustrating the FAAH activity of a rat brain membrane fraction with respect to the hydrolysis of radio-labelled cis-9,10-octadecenoamide to oleic acid and its inhibition by phenylmethyl sulfonyl fluoride (PMSF). Lane number, content: lane 1, Cis-9,10-octadecenoamide standard; lane 2, Cis-9,10-octadecenoamide with rat brain soluble fraction; lane 3, Cis-9,10-octadecenoamide with rat brain membrane fraction; lane 4, Cis-9,10-octadecenoamide with rat brain membrane fraction +1 mM phenylmethylsulfonyl fluoride (PMSF); lane 5, Cis-9,10-octadecenoamide with rat brain membrane fraction +5 mM EDTA; lane 6, Cis-9,10-octadecenoamide with rat pancreatic microsomes; lane 7, Cis-9,10-octadecenoamide with proteinase K (200 mg); lane 8, oleic acid standard.
[0038] FIG. 7 represents an autoradiogram of a thin layer chromatography plate (SiO2, 55% ethyl acetate/hexanes) illustrating the FAAH activity of a rat brain membrane fraction with respect to the hydrolysis of radio-labelled cis-9,10-octadecenoamide to oleic acid and its inhibition by mercuric chloride (HgCl2). The optimal concentrations required for inhibition of amide hydrolysis activity lies between 50 mM and 5 mM HgCl2. The various lanes of the TLC plate are identified as follows: lane 1, Cis-9,10-octadecenoamide standard; lane 2, Cis-9,10-octadecenoamide with rat brain soluble fraction; lane 3, Cis-9,10-octadecenoamide with rat brain membrane fraction and 500 mM HgCl2; lane 4, Cis-9,10-octadecenoamide with rat brain membrane fraction and 50 mM HgCl2; lane 5, Cis-9,10-octadecenoamide with rat brain membrane fraction and 5 mM HgCl2; lane 6, oleic acid standard. A typical HgCl2inhibition study uses a 100 mM HgCl2stock (27 mg in lmL Tris buffer (50 mM), pH 7.5) of HgCl2.
[0039] FIG. 8 represents a northern blot of mRNA obtained from cloning procedures. Ribosomal markers are shown by the arrows, next to lane 1, and indicate 5 kb and 2 kb bands. The arrow next to lane 6 points to a 3 kb band which is representative of the oleic amidase enzyme. Lane 1 is total RNA from rat brain; lane 2 is total RNA from rat lung; lane 3 is total RNA from rat kidney; lane 4 is total RNA from rat heart; lane 5 is total RNA from rat liver; lane 6 is mRNA from rat liver (mRNA loaded in lane 6 is approximately 500 ng); total respective RNA loaded in lanes 1-5 was approximately 15 μg.
[0040] FIG. 9 illustrates the deduced encoded amino acid residue sequence of rat oleamide hydrolase also referred to as a fatty acid amide hydrolase or FAAH (SEQ ID NO: 36). The encoded rat FAAH is appropriately abbreviated rFAAH. Bold type indicates the putative transmembrane spanning domain as predicted by PSORT. The seven discontinuous underlined regions indicate the seven separate peptides, the designation of which is consecutive, obtained by HPLC purification of a trypsin digest of the enzyme. The double-underlined segment is the putative SH3-domain-binding sequence.
[0041] FIGS. 10-1 through 10-5 show the continuous double-stranded cDNA sequence for rat FAAH as described in Section D. The encoded amino acid sequence is also indicated beginning with the ATG start site encoding methionine (M). The stop codon is also shown as boxed. The top and bottom strands of the cDNA sequence are respectively listed in SEQ ID NOs 35 and 37 with the amino acid sequence listed with the nucleotide sequence in SEQ ID NO 35 and by itself in SEQ ID NO 36.
[0042] FIG. 11 illustrates the alignment of the amidase signature sequence region of the rat FAAH (SEQ ID NO 36 from amino acid residue 215 to and including 246) with several other representative amidases as further described in Section D1. Residues of the signature sequence that are completely conserved among the family members are shown in bold type and the relative amino acid position of the signature sequence of each member is given by the numbers just preceding and following the sequence information. From top to bottom, the sequences have the following respective SEQ ID NOs: 36 (from residue 215 to 246) ; 47, 48, 49, 50, 51, 52 and 53.
[0043] FIG. 12A and 12B show the respective results of Southern and Northern blots as probed with an internal 800 bp fragment of rat FAAH cDNA as further described in Section D.
[0044] FIGS. 13-1 through 13-4 show the continuous double-stranded cDNA sequence for mouse FAAH as described in Section D2. The encoded amino acid sequence is also indicated beginning with the ATG start site encoding methionine (M). The stop codon is also shown as boxed. The top and bottom strands of the cDNA sequence are respectively listed in SEQ ID NOs 39 and 41 with the amino acid sequence listed with the nucleotide sequence in SEQ ID NO 39 and by itself in SEQ ID NO 40.
[0045] FIGS. 14-1 through 14-5 show the continuous double-stranded cDNA sequence for human FAAH as described in Section D3. The encoded amino acid sequence is also indicated beginning with the ATG start site encoding methionine (M). The stop codon is also shown as boxed. The top and bottom strands of the cDNA sequence are respectively listed in SEQ ID NOs 42 and 44 with the amino acid sequence listed with the nucleotide sequence in SEQ ID NO 42 and by itself in SEQ ID NO 43.
[0046] FIG. 15A shows the expression of recombinant rat FAAH in COS-7 cells produced as described in Section E as performed by thin layer chromatography demonstrating the conversion of labeled oleamide to oleic acid as further described in Section F.
[0047] FIG. 15B shows the inhibition of recombinant rat FAAH by trifluoromethyl ketone also performed as described in FIG. 15A as further described in Section F.
[0048] FIG. 15C shows the results of Western blotting of recombinant rat FAAH with antibodies generated against peptide 2 as shown in FIG. 9 as shown in the four left lanes (1-4) and as competed with peptide 2 as shown in the four right lanes (5-8). Samples of untransfected COS-7 cell extract are shown in lanes 4 and 8, FAAH-transfected COS-7 cell extracts are shown in lanes 3 and 7, affinity-purified rat FAAH is shown in lanes 2 and 6 and a mixture of FAAH-transfected COS-7 cell extracts and affinity-purified FAAH is run in lanes 1 and 5. The proteins were probed with antibodies in the absence (lanes 1-4) or presence (lanes 5-8) of competing peptide antigen. The FAAH-transfected COS-7 cell extract but not the control contained an immunoreactive 60K-65K protein that was effectively competed away by preincubation of the antibodies with excess peptide antigen while the trace quantities of cross reactive protein observed in both transfected and untransfected COS-7 cell extracts were not competed by the peptide.
[0049] FIG. 16 shows the ability of human recombinant expressed FAAH to hydrolyze oleamide to oleic acid, as further described in FIG. 15A with thin layer chromatography and in Section F.
[0050] FIG. 17 shows the results of thin layer chromatography demonstrating the conversion of labeled anandamide to arachidonic acid in rat FAAH-transfected COS-7 cells as shown in lane 3 but not in control untransfected cells (lane 2). TLC standards of anandamide and arachidonic acid are shown in lanes 1 and 4, respectively.
Detailed Description of the Invention
[0051] A. Protocols for the Induction of Sleep
[0052] Synthetic cis-9,10-octadecenoamide was injected (ip) into rats in order to test its effect on spontaneous behavior at different doses: 1 (n=2), 2 (n=2), 5 (n=7), 10 (n=10), 20 (n=2), and 50 (n=2) mg, where n =number of rats tested. Rats were injected during a reversed dark period (12:12) two hours after the lights cycled off and were observed in their home cages. With the lower doses (1 and 2 mg), no overt effect on spontaneous behavior was witnessed. However, at a threshold of 5 mg and above there was a marked effect consisting of an induction of long-lasting motor quiescence associated with eyes closed, sedated behavior characteristic of normal sleep. Also as with normal sleep, the rats still responded to auditory stimuli with orienting reflex and sustained attention toward the source of stimulation. In addition, motor behavior was impaired. The latency to behavioral sedation following administration was about 4 minutes and subjects were normally active again after 1 hour (5 mg), 2 hour (10 mg), or 2.5 hour (20 mg and 50 mg).
[0053] We have compared cis-9,10-octadecenoamide to vehicle and the synthetic analogs listed in FIG. 1 to estimate the structural specificity of its sleep-inducing potential. Neither vehicle (5% ethanol in saline solution) nor oleic acid (5) showed any overt behavioral effect. Trans-9,10-octadecenoamide demonstrated similar pharmacological effects to its cis counterpart, but was much less potent as measured by the comparatively shorter duration time for its sleep-inducing properties (at 10 mg per rat, the biological effect lasted one hour for the trans isomer and two hours for the cis isomer). When the olefin was moved either direction along the alkyl chain (to the 8,9 (3) or 11,12 (4) positions) or the alkyl chain length was extended to 22 carbons (6), a substantial reduction in both the degree and duration of the pharmacological effects was observed, and while the mobility of the rats still decreased, their eyes remained open and their alertness appeared only slightly affected. Finally, polysomnographic studies on rats injected with cis-9,10-octadecenoamide show an increase in the total time of slow wave sleep (SWS) as well as in the mean duration of the SWS individual periods when compared to vehicle controls. More particularly, male Sprague-Dawley rats (300 g at the time of surgery) were implanted under halothane anesthesia (2-3%) with a standard set of electrodes for sleep recordings. This included two screw electrodes placed in the parietal bone over the hippocampus to record the subjects electroencephalogram (EEG) and two wire electrodes inserted in the neck musculature to record postural tone through electromyographic activity (EMG). Rats were housed individually with at libitum access to food and water. The dark-light cycle was controlled (12:12, lights on a 10:00 p.m.). One week after the surgery, rats were habituated to the recording conditions for at least three days. Upon the completion of the habituation period, rats received 2 milliliter (ip) of either: vehicle (5% ethanol/saline solution), cis-9,10-octadecenoamide (10 mg), or oleic acid (10 mg). Rats were continuously recorded for four hours after the ip injection (12:00 p.m.-4:00 p.m.) Rats were observed for spontaneous changes in behavior through a one-way window. Sleep recordings were visually scored and four stages were determined: wakefulness, slow-wave-sleep 1 (SWS1), slow-wave-sleep 2 (SWS2), and rapid eye movement (REM) sleep.
[0054] These increases with respect to slow wave sleep (SWS) were at the expense of waking. Distribution of REM sleep does not seem to be altered. Together, these data suggest that cis-9,10-octadecenoamide could play an important role in slow-wave sleep modulation.
[0055] The traditional view of lipid molecules as passive structural elements of cellular architecture is rapidly giving way to an ever increasing awareness of the active roles these agents play in transducing cell signals and modifying cell behavior, e.g., Liscovitch et al, Cell,77:329 (1994). An intriguing feature of the fatty acid amides studied here is that they belong to a family of simple molecules in which a great deal of diversity may be generated by simply varying the length of the alkane chain and the position, stereochemistry, and number of its olefin(s). Interestingly, other neuroactive signalling molecules with amide modifications at their carboxy termini have been reported, from carboxamide terminal peptides to arachidonylethanolamide. Neuroactive signalling molecules employing carboxamide terminal peptides are disclosed by Eipper et al, Annu. Rev. Neurosci.,15:57 (1992). Neuroactive signalling molecules employing arachidonylethanolamide is disclosed by Devane et al, Science,258:1946 (1992). It is disclosed herein that cis-9,10-octadecenoamide is a member of a new class of biological effectors in which simple variations of a core chemical structure have unique physiological consequences.
[0056] B. Isolation and Assay of Integral Membrane Protein Fraction with FAAH Activity
[0057] 1. Observations on Lipid Amidase Activity
[0058] Lipid amidase activity has been observed in brain, liver, lung, kidney and spleen tissues, but not in heart tissue. The activity is inhibited by 1 mM PMSF (phenylmethylsulfonyl fluoride) and 50 mM HgCl, which is a test for sulfhydryl group dependency of the reaction. Since the fractions are not solubilized by 100 mM sodium carbonate (pH 11.5), the sample is apparently a membrane protein, which has been identified in nuclear, microsomal, and plasma membrane subcellular fractions, but not in the cytosol.
[0059] The enzyme catalyzed hydrolysis of cis-9,10-octadecenoamide to oleic acid by purified cis-9,10-octadecenoamide and inhibition of this enzyme by PMSF is disclosed on an autoradiogram of a thin layer chromatographic plate (SiO2, 55% ethyl acetate/hexanes), illustrated in FIG. 6. In each case the enzymic reaction is performed is a separate reaction vessel and the product is spotted onto a TLC plate. The various reaction conditions for the reaction vessel corresponding to each lane are identified as follows:
[0060] lane 1: Cis-9,10-octadecenoamide standard;
[0061] lane 2: Cis-9,10-octadecenoamide with rat brain soluble fraction;
[0062] lane 3: Cis-9,10-octadecenoamide with rat brain membrane fraction;
[0063] lane 4: Cis-9,10-octadecenoamide with rat brain membrane fraction +1 mM PMSF;
[0064] lane 5: Cis-9,10-octadecenoamide with rat brain membrane fraction +5 mM EDTA;
[0065] lane 6: Cis-9,10-octadecenoamide with rat pancreatic microsomes;
[0066] lane 7: Cis-9,10-octadecenoamide with proteinase K (200 mg); and
[0067] lane 8: oleic acid standard.
[0068] Inhibition studies of Cis-9,10-octadecenoamide hydrolysis to oleic acid with HgCl2are illustrated in FIG. 7. Between 50 mM and 5 mM HgCl2lies the optimal concentrations required for inhibition of amide hydrolysis activity. The enzyme catalyzed hydrolysis of cis-9,10-octadecenoamide to oleic acid by purified cis-9,10-octadecenoamide and inhibition of this enzyme by HgCl2is performed in a series of reaction vessels and spotted onto a thin layer chromatographic plate (SiO2, 55% ethyl acetate/hexanes). A typical HgCl2inhibition study uses a 100 mM HgCl2stock (27 mg in lmL Tris buffer (50 mM), pH 7.5) of HgCl2. The various reaction conditions for the reaction vessels corresponding to each lane are identified as follows:
[0069] lane 1: Cis-9,10-octadecenoamide standard;
[0070] lane 2: Cis-9,10-octadecenoamide with rat brain soluble fraction;
[0071] lane 3: Cis-9,10-octadecenoamide with rat brain membrane fraction and 500 mM HgCl2;
[0072] lane 4: Cis-9,10-octadecenoamide with rat brain membrane fraction and 50 mM HgCl2;
[0073] lane 5: Cis-9,10-octadecenoamide with rat brain membrane fraction and 5 mM HgCl2;
[0074] A unique enzymatic activity capable of degrading the putative effector molecule, cis-9,10-octadecenoamide has been identified and is disclosed herein. Rapid conversion of 14C-cis-9,10-octadecenoamide to oleic acid by rat brain membrane fractions was observed by TLC. The enzymatic activity was unaffected by 5 mM EDTA, but was completely inhibited by 1 mM phenylmethylsulfonyl fluoride (PMSF). Only trace amide hydrolysis activity was observed with rat brain soluble fractions, while rat pancreatic microsomes and proteinase K showed no significant capacity to hydrolyze cis-9,10-octadecenoamide to oleic acid.
[0075] 2. Synthesis of Fatty Acid Primary Amides
[0076] Preferred protocols for synthesizing exemplary fatty acid primary amides are provided. The synthetic protocols differ only with respect to the chain length of the starting materials, the product yields, and the separation of the various cis and trans products. Accordingly, exemplary descriptions of synthetic protocols for the synthesis of cis-9,10-octadecenoamide and several other fatty acid primary amides are provided and serve to illustrate the synthetic protocol for the entire class of fatty acid primary amides.
[0077] 3. Isolation of Rat Integral Membrane Protein Fraction with FAAH Activity
[0078] The protocol described herein is for about 5-10 g of tissue. The rat liver(s) are collected, weighed and then placed in 1 mM NaHCO3on ice. Next, the liver is cut up, rinsed (2×) with 1 mM NaHCO3and minced with a razor blade on a sheet of wax. It is then placed into 25 ml of 1 mM sodium bicarbonate and homogenized in a tissuemizer for 2 minutes at setting 6. A dilution to 100 ml with 1 mM sodium bicarbonate is subsequently performed, which is followed by a filtration through 4 layers of cheesecloth and then through 8 layers. The filtrate is then brought up to 100 ml and split into four JA-20 tubes and topped off with 1 mM sodium bicarbonate. The tubes are spun at 6,000 rpm (4500×g) for 12 minutes at 4° C. in the JA-20 rotor. Using a Pasteur pipette, the fat layer is sucked off and the supernatant layer is decanted and saved.
[0079] Next, the pellet is resuspended in the remaining supernatant layer with a syringe and needle. 20 mL fractions of the resuspension are then dounced 16 times with a 15 ml dounce homogenizer. The fractions are then combined into a single JA-20 tube and brought up to volume with 1 mM NaHCO3. The tubes are next spun again at 6,000 rpm (4500×g) for 15 minutes at 4° C. in a JA-20 rotor and the supernatant is subsequently poured off and saved. The pellet is resuspended and dounced as before and then brought up to 10 ml volume with lmM sodium bicarbonate. Next, 20 mL of 67% sucrose solution is added to a final volume of 30 ml and the mixture is split into 2 tubes. An additional 25 mL of 30% sucrose is added to the top of each tube and spun at 27 K rpm for 1 hour 45 minutes at 4° C. in an ultracentrifuge. The fractions are collected from the sucrose gradient and the middle band from the sucrose gradient (plasma membrane band) is placed in a capped plastic tube and filled with 1 mM sodium bicarbonate. The tube is subsequently spun at 17,000 rpm for 35 minutes at 4° C.
[0080] The supernatant is discarded and the pellets are resuspended (with Douncing) in 100 mM of sodium carbonate. This solution is subsequently kept on ice for 1 hour and then spun at 100,000 g for 1 hour. The supernatant (solubilized peripheral membrane proteins) is discarded since no lipid amidase activity is present in this fraction and the pellet is resuspended (with Douncing) in 10% glycerol, 1% Triton, 0.1% phosphatidyl choline, 20 mM Hepes buffer and then stirred for two hours at 4° C. Finally the solution is spun at 100,000 g for 1 hour and the supernatant thus obtained is further purified as follows. 4. Purification Via 4 Step Column Chromatography Process
[0081] Step 1 DEAE column/ ion exchange (FIG. 3). The above solubilized supernatant batch is further purified. The supernatant batch is mixed with DEAE-Sephadex (Diethylaminoethyl-Sephadex, commercially available from Sigma chemical company) ion exchange resin for 1 hour at 40° C. The fraction which is bound to the DEAE resin, displays the lipid amidase activity (none in flow through). Solubilized rat liver plasma membrane (in BI: 10% glycerol, 1% Triton X-100, 1 mM EDTA, 20 mM Hepes, pH 7.2) is passed over DEAE Fast Flow column (Pharmacia) and washed with 5 column volumes of BI, 0.2% Triton. Then the amidase activity is eluted with 1 column volume each of 50 mM, 100 mM, and 200 mM NaCl in BI with 0.2% Triton.
[0082] Step 2 Hg Column (FIG. 3). The above eluent from the DEAE exchange, is mixed with p-chloromercuric benzoic acid resin (Commercially available from BioRad chemical company) for 1 hour at 4° C. The fraction which is bound to the above mercury resin, displays the lipid amidase activity (none in flow through), is washed with 5 column volumes of BI with 0.2% Triton, 5 column volumes of BI with 0.2% Triton and 150 mM NaCl, and eluted with 1.5 column volumes BI with 0.2% Triton, 150 mM NaCl, and 25 mM b-mercaptoethanol.
[0083] Step 3 Heparin column (FIG. 3). Hg-eluted amidase activity was passed over Heparin column (BioRad) and washed with 10 column volumes of BI with 0.7% CHAPS and 150 mM NaCl (detergent exchange). Elution was conducted with 1 column volume each of BI with 0.7% CHAPS and 300 mM, 400 mM, 500 mM, 650 mM, and 750 mM NaCl,respectively, with amidase activity eluting in the final two fractions.
[0084] Step 4 Affinity column (FIGS. 3 and 4). Heparin-eluted amidase activity was mixed with Triton X-100 for a final concentration of 0.2%, and then passed over CF3-inhibitor linked to activated pyridyl disulphide beads (103: attachment of inhibitor to beads is described infra) and washed with 20 column volumes of BI with 0.2% Triton X-100. Elution was conducted by passing 3 column volumes of BI with 0.2% Triton and 20 mM DTT, and letting column stand at 4o C for 30 h. Then, washing column with 1.5 column volumes of BI with 0.2% Triton and 20 mM DTT eluted single protein of 60 kD in size.
[0085] Eluted 60 kd protein was digested with trypsin and peptides were sequenced as described infra.
[0086] The purity of the activity is then assessed after this procedure according to an assay protocol.
[0087] 5. Assay for Fatty-Acid Amide Hydrolase Activity:
[0088] The following thin layer chromatography (TLC) protocol is used for assaying cis-9,10 octadecenoamide hydrolysis activity, also referred to as fatty-acid amide hydrolase activity. Oleamide is first labeled with 14C. To accomplish this, 14C-Oleic acid (1-10 μM, Moravek Biochemicals, 5-50 μCi/μM) in CH2CL2(200 μL, 0.005-0.05 M) at 0° C. was treated with excess oxalyl chloride and the reaction mixture was warmed to 25° C. for 6 hours. The reaction mixture was then concentrated under a constant stream of gaseous nitrogen and the remaining residue was cooled to 0° C. and treated with excess saturated aqueous ammonium hydroxide. After 5 minutes, the reaction mixture was partitioned between Et)Ac (1.5 mL) and 10% HCl (1.0 mL). The organic layer was then washed with water (1.0 mL) and concentrated under a constant stream of gaseous nitrogen to provide 14C-oleamide in quantitative yield as judged by TLC (60% EtOAc in hexanes; oleamide Rf-0.2; oleic acid Rf-0.8).
[0089] Approximately 1 μCi of 14C-oleamide (specific activity 5-50 μCi/M) in ethanol was incubated at 37° C. for 1-2 hours with 70 μL of 126 mM Tris-HCl, pH 9.0 (final concentration of ethanol was 2.0%). The reaction mixture was then partitioned between ethyl acetate (1.0 mL) and 0.07 M Hcl (0.6 mL). The ethyl acetate layer was concentrated under a constant stream of gaseous nitrogen and the remaining residue was resuspended in 15 μL of ethanol. Approximately 3 ML of this ethanol stock was then used for TLC analysis (60% EtOAc in hexanes: oleamide Rf-0.2; oleic acid Rf-0.8). Following exposure to solvent, TLC plates were air-dired, treated with EN3HANCE spray (Dupont NEN) according to manufacturer's guidelines and exposed to film at −78° C. for 1-2 hours.
[0090] The purified protein was determined to have a 20-30 fold enrichment of amidase activity from crude membrane protein fraction by visual comparison of the purified protein band intensity with the crude protein fraction. Estimated purified yield is 10-15% (FIG. 3)
[0091] C. Synthetic Protocols
[0092] 1. Cis-9,10-octadecenoamide (1: FIG. 1):
[0093] A solution of oleic acid (1.0 g, 3.55 mmol, 1.0 equiv.) in CH2Cl2(8.9 mL, 0.4 M) at 0° C. was treated dropwise with oxalyl chloride (5.32 mL, 2.0 M solution in CH2Cl2, 10.64 mmol, 3.0 equiv.). The reaction mixture was stirred at 25° C. for 4 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH4OH (2.0 mL). The reaction mixture was then partitioned between ethyl acetate (EtOAc) (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2, 5 cm×15 cm, 40-100% EtOAc-hexanes gradient elution) afforded 1 as a white solid (0.810 g, 0.996 g theoretical, 81.3%): 1H NMR (CDCl3, 250 MHz) δ 6.06 (bs, 1H, NH2C(O)), 5.58 (bs, 1H, NH2C(O)), 5.32 (m, 2H, CH═CH), 2.16 (t, 2H, J=7.5 Hz, CH2C(O)NH2), 2.02 (m, 4H, CH2CH═CHCH2), 1.61 (m, 2H, CH2CH2C(O)NH2), 1.29 (b s, 14H, alkyl protons), 0.87 (t, 3H, CH3); FABHRMS (NBA/NaI m/e 282.2804 (C18H35NO+H+ requires 282.2797). The regions of the spectra that distinguish between the cis and trans isomers are the olefinic protons from δ 5.3 to 5.2 and allylic protons from δ 2.0 to 1.8. These regions identify the natural compound as cis-9,10-octadecenoamide.
[0094] 2. Trans-9,10-octadecenlamide (2: FIG. 1)
[0095] A solution of elaidic acid (1.0 g, 3.55 mmol, 1.0 equiv.) in CH2Cl2(8.9 mL, 0.4 M) at 0° C. was treated dropwise with oxalyl chloride (5.32 mL, 2.0 M solution in CH2Cl2,10.64 mmol, 3.0 equiv.). The reaction mixture was stirred at 25° C. for 4 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH4OH (2.0 mL). The reaction mixture was then partitioned between ethyl acetate (EtOAc) (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 40-100% EtOAc-hexanes gradient elution) afforded 2 as a white solid. The regions of the spectra that distinguish between the cis and trans isomers are the olefinic protons from δ 5.3 to 5.2 and allylic protons from δ 2.0 to 1.8. These regions identify the compound as trans-9,10-octadecenoamide.
[0096] 3. Cis-8,9-octadecenoamide (3: FIG. 1):
[0097] A solution of 11, synthesized infra, (0.130 g, 0.461 mmol, 1.0 equiv.) in CH2Cl2(1.5 mL, 0.31 M) at 0° C. was treated dropwise with oxalyl chloride (0.69 mL, 2.0 M solution in CH2Cl2,1.38 mmol, 3.0 equiv.). The reaction mixture was stirred at 25° C. for 4 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH4OH (2.0 mL). The reaction mixture was then partitioned between ethyl acetate (EtOAc) (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 40-100% EtOAc-hexanes gradient elution) afforded 3 as a white solid. (0.105 g, 0.130 theoretical, 80.8%): 1H NMR (CDCl3,250 MHz) δ 5.70-5.34 (m, 4H, H2NC(O) and CH═CH), 2.21 (t, 2H, J=7.5 Hz, CH2C(O)NH2), 2.00 (m, 4H, CH2CH═CHCH2), 1.63 (m, 2H, CH2CH2C(O)NH2), 1.47-1.23 (m, 20H, alkyl protons), 0.87 (t, 3H, RCH3); FABHRMS (NBA/CSI m/e 414.1762 (C18H35NO+Cs+ requires 414.1773).
[0098] 4. Cis-11,12-octadecenoamide (4: FIG. 1):
[0099] A solution of &11,12 octadecenoic acid (1.0 g, 3.55 mmol, 1.0 equiv.) in CH2Cl2(8.9 mL, 0.4 M) at 0° C. was treated dropwise with oxalyl chloride (5.32 mL, 2.0 M solution in CH2Cl2,10.64 mmol, 3.0 equiv.). The reaction mixture was stirred at 25° C. for 4 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH40H (2.0 mL). The reaction mixture was then partitioned between ethyl acetate (EtOAc) (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 40-100% EtOAc-hexanes gradient elution) afforded 4 as a white solid.
[0100] 5. Oleic acid (5: FIG. 1)
[0101] Oleic acid was obtained from Aldrich chemical company, CAS #112-80-1.
[0102] 6. Erucamide (6: FIG. 1)
[0103] Erucamide was obtained from Aldrich Chemical Company, CAS #28,057-7.
[0104] 7. Methyl-8-hydroxy-octanoate (7: Scheme 3)
[0105] A solution of suberic acid monomethyl ester (1.5 g, 7.97 mmol, 1.0 equiv.) in tetrahydrofuran (THF) (32.0 mL, .25M) at −20° C. was treated dropwise with BH3.THF (IM solution in THF, 7.97 mL, 7.97 mmol, 1.0 equiv.). The reaction mixture was stirred overnight and was subsequently allowed to reach room temperature. The reaction mixture was then diluted with ethyl acetate (100 mL) and quenched with methanol (10 mL) and 10% HCl (10 mL). Extraction with NaHCO3(1×20 mL), water (2×10 mL), and brine (1×10 mL), afforded methyl-8-hydroxy-octanoate
[0106] (7) as a crude white solid.
[0107] 8. Methyl-8-bromo-octanoate (8: Scheme 3)
[0108] A solution of crude methyl-8-hydroxy-octanoate (7, 1.24 g, 7.13 mmol, 1.0 equiv.) in CH2Cl2(15 mL, 0.48 M) at 0° C. was treated successively with CBr4(3.07 g, 9.27 mmol, 1.3 equiv.) and PPh3(2.61 g, 9.98 mmol, 1.4 equiv.) and the reaction mixture was stirred at 4° C. for 10 h. The reaction mixture was then concentrated under reduced pressure and washed repeatedly with Et2O (8×10 mL washes). The Et2O washes were combined and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, hexanes) afforded 8 as a clear, colorless oil (1.25 g, 1.69 g theoretical, 74.0%): 1H NMR (CDCl3,250 MHz) δ 3.64 (s, 3H, C(O)OCH3), 3.38 (t, 2H, J=6.8 Hz, CH2Br), 2.29 (t, 2H, J=7.4 Hz CH2C(O)OCH3), 1.83 (p, 2H, CH2CH2Br), 1.63 (m, 2H, CH2CH2C(O)OCH3) 1.47-1.28 (m, 6H, alkyl protons).
[0109] 9. Methyl-8-triphenylphosphoranyl-octanoate-bromide (9: Scheme 3)
[0110] A solution of 8 (1.25 g, 5.23 mmol, 1.0 equiv.) in CH3CN (4.0 mL, 1.31 M) was treated with triphenylphosphine (1.52 g, 5.75 mmol, 1.1 equiv.) and stirred at reflux for 10 h. Additional triphenylphosphine (0.685 g, 2.61 mmol, 0.5 equiv.) was added to the reaction mixture and stirring was continued at reflux for 5 h. The reaction mixture was concentrated under reduced pressure and washed repeatedly with Et2O (5×10 mL washes). The remaining residue was then solubilized in the minimum volume of CH2Cl2and concentrated under reduced pressure to afford 9 as a colorless foam (2.20 g, 2.61 g theoretical, 84.3%): 1H NMR (CDCl3,250 MHz) δ 7.82-7.51 (m, 15H, ArH), 3.70-3.46 (m, 5H, CH3OC(O)R and CH2PPh3), 2.13 (t, 2H, J=7.4 Hz, CH2C(O)OCH3, 1.62-1.43 (m, 6H, alkyl protons), 1.30-1.02 (m, 4H, alkyl protons); FABHRMS (NBA) m/e 419.2154 (C27H32BrO2P—Br− requires 419.2140).
[0111] 10. Methyl-cis-8. 9-octadecenoate (10: Scheme 3
[0112] A solution of 9 (0.71 g, 1.42 mmol, 1.0 equiv.) in THF (7.0 mL, 0.2 M) at 25° C. was treated with KHMDS (3.0 mL, 0.5 M solution in THF, 1.5 mmol, 1.06 equiv.) and the reaction mixture was stirred at reflux for 1 h. The reaction mixture was then cooled to −78 ° C., treated with decyl aldehyde (0.321 mL, 1.71 mmol, 1.2 equiv.) warmed to 25° C., and stirred for an additional 30 min. The reaction mixture was then treated with saturated aqueous NH4Cl and partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 0-2% EtOAc-hexanes gradient elution) afforded 10 as a colorless oil (0.290 g, 0.422 g theoretical, 68.7 %): 1H NMR (CDCl3,250 MHz) δ 5.34 (m, 2H, CH═CH), 3.65 (s, 3H, CH3OC(O)), 2.29 (t, 2H, J=7.4 Hz, CH2C(O)OCH3), 2.00 (m, 4H, CH2CH═CHCH2), 1.61 (m, 2H, CH2CH2C(O)OCH3), 1.29 (bs, 20 H, alkyl protons), 0.86 (t, 3H, RCH3).
[0113] 11. Cis-8,9octadecenoic acid (11: Scheme 3)
[0114] A solution of 10 (0.245 g, 0.825 inmol, 1.0 equiv.) in THF-MeOH-H2O (3-1-1 ratio, 4.1 mL, 0.2 M) at 0° C. was treated with LiOH.H2O (0.104 g, 2.48 mrmol, 3.0 equiv.). The reaction mixture was warmed to 25° C., stirred for 8 h, and then partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was washed successively with 10% aqueous HCl (100 mL) and saturated aqueous NaCl (100 mL), dried, and concentrated under reduced pressure. Chromatography (SiO2,5cm×15 cm, 10-30% EtOAc-hexanes gradient elution) afforded 11 as a colorless oil (0.156 g, 0.233 g theoretical, 67.0%): 1H NMR (CDCl3,250 MHz) δ 5.34 (m, 2H, CH═CH), 2.34 (t, 2H, J=7.4 Hz, CH2COOH), 2.01 (m, 4H, CH2CH═CHCH2), 1.61 (m, 2H, CH2CH2COOH), 1.47-1.23 (m, 20 H, alkyl protons), 0.87 (t, 3H, RCH3).
[0115] 12. 18-Hemisuccinate-cis-9,10-octadecenoamide (12: Scheme 4)
[0116] A solution of 18 (0.047 g, 0.160 M, 1.0 equiv) in CH2Cl2—CHCl3(3-1, 1.60 mL, 0.1M) was treated successively with Et3N (0.045 mL, 0.320 mmol, 2.0 equiv), succinic anhydride (0.033 g, 0.320 mmol, 2.0 equiv) and DMAP (0.002 g, 0.016 mmol, 0.1 equiv), and the reaction mixture was stirred at 25° C. for 10 h. The reaction mixture was then partitioned between CH2Cl2(50 mL) and H2O (50 mL), and the organic layer was washed successively with 10% aqueous HCl (50 mL) and saturated aqueous NaCl (50 mL), dried (Na2SO4), and concentrated under reduced pressure. Chromatography (SiO2,3 cm×15 cm, 0-10% MeOH-EtOAc) afforded 12 as a white solid (0.051 g, 0.063 theoretical, 80.3%): 1H NMR (CDCl3,250 MHz) δ 6.95 (b s, 1H, H2NC(O)), 5.72 (b s, 1H, H2NC(O)), 5.34 (m, 2H, CH═CH), 4.08 (t, 3H, J=6.6 Hz, CH2OC(O)R), 2.61 (m, 4H, ROC(O)CH2CH2COOH), 2.21 (t, 2H, J=7.5 Hz, CH2C(O)NH2), 2.00 (m, 4H, CH2CH═CHCH2), 1.70-1.52 (m, 4H, CH2CH2C(O)NH2and CH2CH2OH), 1.29 (b s, 18H, alkyl protons); FABHRMS (NBA) m/e 398.2893 (C22H39NO5+H+requires 398.2906).
[0117] 13. Methyl-9-bromo-nonanoate (13: Scheme 4)
[0118] A solution of methyl-9-hydroxy-nonanoate (1.1 g, 5.85 mmol, 1.0 equiv) in CH2Cl2(30 mL, 0.2 M) at 0° C. was treated successively with CBr4(2.5 g, 7.54 mmol, 1.3 equiv) and PPh3(2.15 g, 8.19 mmol, 1.4 equiv) and the reaction mixture was stirred at 4° C. for 10 h. The reaction mixture was then concenctrated under reduced pressure and washed repeatedly with Et2O (8×10 mL washes). The Et2o washes were combined and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, hexanes) afforded 13 as a clear, colorless oil (1.02 g, 1.47 g theorectical, 69.5 %): 1H NMR (CDCl3,250 MHz) d 3.64 (s, 3H, C(O)OCH3), 3.38 (t, 2H, J=6.8 Hz, CH2Br), 2.29 (t, 2H, J=7.4 Hz CH2C(O)OCH3), 1.83 (p, 2H, CH2CH2Br), 1.63 (m, 2H, CH2CH2C(O)OCH3) 1.47-1.28 (m, 8H, alkyl protons).
[0119] 14. Methyl-9-triphenylphosphoranyl-nonanoate-bromide (14: Scheme 4)
[0120] A solution of 13 (1.02 g, 4.06 mmol, 1.0 equiv) in CH3CN (3.5 mL, 1.16 M) was treated with triphenylphosphine (1.17 g, 4.47 mmol, 1.1 equiv) and stirred at reflux for 10 h. Additional triphenylphosphine (0.532 g, 2.03 mmol, 0.5 equiv) was added to the reaction mixture and stirring was continued at reflux for 5 h. The reaction mixture was concentrated under reduced pressure and washed repeatedly with Et2O (5×10 mL washes). The remaining residue was then solubilized in the minimum volume of CH2Cl2and concentrated under reduced pressure to afford 14 as a colorless foam (1.90 g, 2.08 g theoretical, 91.3%): 1H NMR (CDCl3,250 MHz) δ 7.82-7.51 (m, 15H, ArH), 3.70-3.46 (m, 5H, CH3OC(O)R and CH2PPh3), 2.13 (t, 2H, J=7.4 Hz, —CH2C(O)OCH3), 1.62-1.02 (m, 12H, alkyl protons); FABHRMS (NBA) m/e 433.2312 (C28H34BrO2P—Br− requires 433.2296).
[0121] 15. Methyl-18-t-butyldiphenysilyloxy-cis-9,10 octadecenoate (15: Scheme 4)
[0122] A solution of 14 (1.0 g, 1.95 mmol, 1.0 equiv) in THF (6.5 mL, 0.3 M) at 25° C. was treated with KHMDS (3.9 mL, 0.5 M solution in THF, 1.95 mmol, 1.0 equiv) and the reaction mixture was stirred at reflux for 1 h. The reaction mixture was then cooled to −78° C., treated with 3 (0.93 g, 2.35 mmol, 1.2 equiv), warmed to 25° C., and stirred for an additional 30 min. The reaction mixture was then treated with saturated aqueous NH4C1 and partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 0-2% EtOAc-hexanes gradient elution) afforded 15 as a colorless oil (0.82 g, 1.07 g theoretical, 76.3%): 1H NMR (CDCl3,250 MHz) δ 7.67 (m, 4H, ArH), 7.41 (m, 6H, ArH), 5.34 (m, 2H, CH═CH), 3.65 (m, 5H, CH3OC(O) and CH2OTBDPS), 2.29 (t, 2H, J=7.4 Hz, CH2C(O)OCH3), 2.00 (m, 4H, CH2CH═CHCH2), 1.55 (m, 4H, CH2CH2C(O)OCH3and CH2CH2OTBDPS), 1.29 (b s, 18H, alkyl protons), 1.04 (s, 9H, (CH3)3C).
[0123] 16. 18-T-butyldiphenylsilyloxy-cis-9,10-octadecenoic acid (16: Scheme 4)
[0124] A solution of 5 (0.81 g, 1.47 mmol, 1.0 equiv) in THF-MeOH-H2O (3-1-1 ratio, 7.3 mL, 0.2 M) at 0° C. was treated with LiOH.H2O (0.188 g, 4.48 mmol, 3.0 equiv). The reaction mixture was warmed to 25° C., stirred for 8 h, and then partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was washed successively with 10% aqueous HCl (100 mL) and saturated aqueous NaCl (100 mL), dried, and concentrated under reduced pressure. Chromatography (SiO2, 5 cm×15 cm, 10-30% EtOAc-hexanes gradient elution) afforded 16 as a colorless oil (0.700 g, 0.790 g theoretical, 88.7%): 1H NMR (CDCl3, 250 MHz) δ 7.67 (m, 4H, ArH), 7.41 (m, 6H, ArH), 5.34 (m, 2H, CH═CH), 3.65 (t, 3H, J=6.5 Hz, CH2OTBDPS), 2.34 (t, 2H, J=7.4 Hz, CH2COOH), 2.00 (m, 4H, CH2CH═CHCH2), 1.65-1.50 (m, 4H, CH2CH2COOH and CH2CH2OTBDPS), 1.47-1.23 (m, 18H, alkyl protons), 1.05 (s, 9H, (CH3)3C); FABHRMS (NBA/CsI) m/e 669.2772 (C34H52O3Si+Cs+ requires 669.2740).
[0125] 17. 18-T-butyldiphenylsilyloxy-cis-9,10-octadecenoamide (17: Scheme 4)
[0126] A solution of 16 (0.685 g, 1.28 mmol, 1.0 equiv) in CH2Cl2(4.3 mL, 0.3 M) at 0° C. was treated dropwise with oxalyl chloride (1.92 mL, 2 M solution in CH2Cl2,3.84 mmol, 3.0 equiv). The reaction mixture was stirred at 25° C. for 4 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH4OH (2.0 mL). The reaction mixture was then partitioned between EtOAc (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 40-100% EtOAc-hexanes gradient elution) afforded 17 as a colorless oil (0.520 g, 0.684 g, 76.0%): 1H NMR (CDCl3,250 MHz) δ 7.67 (m, 4H, ArH), 7.41 (m, 6H, ArH), 5.70-5.34 (m, 4H, H2NC(O) and CH═CH), 3.65 (t, 3H, J=6.5 Hz, CH2OTBDPS), 2.21 (t, 2H, J=7.5 Hz, CH2C(O)NH2), 2.00 (m, 4H, CH2CH═CHCH2), 1.65-1.50 (m, 4H, CH2CH2C(O)NH2and CH2CH2OTBDPS), 1.47-1.23 (m, 18H, alkyl protons), 1.05 (s, 9H, (CH3)3C); FABHRMS (NBA/CsI m/e 668.2929 (C34H53O2NSi+Cs+ requires 668.2900).
[0127] 18. 18-Hydroxy-cis-9,10-octadecenoamide (18: Scheme 4)
[0128] A solution of 17 (0.185 g, 0.345 mmol, 1.0 equiv) in THF (1.1 mL, 0.31 M) was treated with tetrabutylammoniumfluoride (0.69 mL, 1.0 M solution in THF, 0.69 mmol, 2.0 equiv) and the reaction mixture was stirred at 25° C. for 2 h. The reaction mixture was then partitioned between EtOAc (50 mL) and H2O (50 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure . Chromatography (SiO2,3 cm×15 cm, 0-5% MeOH-EtOAc gradient elution) afforded 18 as a white solid (0.097 g, 0.103 g theoretical, 94.6%): 1H NMR (CDCl3,250 MHz) δ 5.65-5.34 (m, 4H, H2NC(O) and CH═CH), 3.62 (t, 3H, J=6.5 Hz, CH2OH), 2.21 (t, 2H, J=7.5 Hz, CH2C(O)NH2), 2.00 (m, 4H, CH2CH═CHCH2), 1.65-1.50 (m, 4H, CH2CH2C(O)NH2and CH2CH20H), 1.29 (b s, 18H, alkyl protons); FABHRMS (NBA) 298.2732 (C18H35NO2+H+ requires 298.2746).
[0129] 19. Synthesis of Compound 100 (FIG. 5)
[0130] Methyl-9-t-butyldiphenylsilyloxy-nonanoate (intermediate for compound 100: FIG. 5). A solution of methyl-9-hydroxy-nonanoate (0.838 g, 4.46 mmol, 1.0 equiv: Aldrich) in CH2Cl2(15 mL, 0.3 M) was treated successively with Et3N (0.75 mL, 5.38 mmol, 1.2 equiv), t-butylchlorodiphenylsilane (1.28 mL, 4.93 mmol, 1.1 equiv), and DMAP (0.180 g, 1.48 mmol, 0.33 equiv), and the reaction mixture was stirred at 25° C. for 12 h. Saturated aqueous NH4Cl was added to the reaction mixture and the mixture was partitioned between CH2Cl2(100 mL) and H2O (100 mL). The organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (SiO2, 5 cm×15 cm, 0-5% EtOAc-hexanes gradient elution ) afforded the intermeidate as a clear, colorless oil (1.22g, 1.831 theoretical, 64.1%): 1H NMR (CDCl3,250 MHz) δ 7.66 (m, 4H, ArH), 7.38 (m, 6H, ArH), 3.67-3.62 (m, 5H, C(O)OCH3and CH2OTBDPS), 2.30 (t, 2H, J=7.4 Hz, CH2C(O)OCH3), 1.58 (m, 4H, CH2CH2OTBDPS and CH2CH2C(O)OCH3), 1.28 (b s, 8H, alkyl protons), 1.05 (s, 9H, C(CH3) 3)
[0131] 20. Methyl-9-bromo-nonanoate (Intermediate for Compound 100: FIG. 5)
[0132] A solution of methyl-9-hydroxy-nonanoate (1.1 g, 5.85 mmol, 1.0 equiv) in CH2Cl2(30 mL, 0.2 M) at 0° C. was treated successively with CBr4(2.5 g, 7.54 mmol, 1.3 equiv) and PPh3(2.15 g, 8.19 mmol, 1.4 equiv) and the reaction mixture was stirred at 4° C. for 10 h. The reaction mixture was then concenctrated under reduced pressure and washed repeatedly with Et2O (8×10 mL washes). The Et2O washes were combined and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, hexanes) afforded the intermediate as a clear, colorless oil (1.02 g, 1.47 g theorectical, 69.5 %): 1H NMR (CDCl3,250 MHz) d 3.64 (s, 3H, C(O)OCH3), 3.38 (t, 2H, J=6.8 Hz, CH2Br), 2.29 (t, 2H, J=7.4 Hz CH2C(O)OCH3), 1.83 (p, 2H, cH2CH2Br), 1.63 (m, 2H, CH2CH2C(O)OCH3) 1.47-1.28 (m, 8H, alkyl protons).
[0133] 21. 9-T-butyldiphenylsilyloxy-nonanal (Intermediate for Compound 100: FIG. 5)
[0134] A solution of 1 (1.25 g, 2.93 mmol, 1.0 equiv) in toluene (9.80 mL, 3.0 N) at −78° C. was treated dropwise with DIBAL-H (4.40 mL, 1.0 M solution in hexanes, 4.40 mmol, 1.5 equiv). The reaction mixture was stirred at −78° C. for 30 min. The reaction mixture was then treated dropwise with MeOH (2 mL) and partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was washed with 10 % aqueous HCl (100 mL), dried (Na2SO4), and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 0-5 % EtOAc-hexanes gradient elution) afforded 3 as a colorless oil (1.1 g, 94.9 %): 1H NMR (CDCl3,250 MHz) 6 9.76 (t, 1H, J=1.8 Hz, HC(O)R), 7.67 (m, 4H, ArH), 7.40 (m, 6H, ArH), 3.65 (t, 2H, J=6.4 Hz, CH2OTBDPS), 2.41 (t of d, 2H J=1.8 and 7.3 Hz, CH2C(O)H), 1.58 (m, 4H, CH2CH2OTBDPS and CH2CH2C(O)H), 1.29 (b s, 8H, alkyl protons), 1.05 (s, 9H, (CH3)3C); FABHRMS (NBA/CsI) m/e 529.1560 (C25H36O2Si+Cs+ requires 529.1539).
[0135] 22. Methyl-9-triphenylphosphoranyl-nonanoate Bromide (Intermediate for Compound 100: FIG. 5)
[0136] A solution of 9-T-butyldiphenylsilyloxy-nonanal (1.02 g, 4.06 mmol, 1.0 equiv) in CH3CN (3.5 mL, 1.16 M) was treated with triphenylphosphine (1.17 g, 4.47 mmol, 1.1 equiv) and stirred at reflux for 10 h. Additional triphenylphosphine (0.532 g, 2.03 mmol, 0.5 equiv) was added to the reaction mixture and stirring was continued at reflux for 5 h. The reaction mixture was concentrated under reduced pressure and washed repeatedly with Et2O (5×10 mL washes). The remaining residue was then solubilized in the minimum volume of CH2Cl2and concentrated under reduced pressure to afford the intermediate as a colorless foam (1.90 g, 2.08 g theoretical, 91.3%): 1H NMR (CDCl3,250 MHz) δ 7.82-7.51 (m, 15H, ArH), 3.70-3.46 (m, 5H, CH3OC(O)R and CH2PPh3), 2.13 (t, 2H, J=7.4 Hz, CH2C(O)OCH3), 1.62-1.02 (m, 12H, alkyl protons); FABHRMS (NBA) m/e 433.2312 (C28H34BrO2P—Br− requires 433.2296).
[0137] 23. Methyl-18-t-butyldiphenysilyloxy-cis-9,10-octadecenoate (Intermediate for Compound 100: FIG. 5)
[0138] A solution of (1.0 g, 1.95 mmol, 1.0 eguiv) in THF (6.5 mL, 0.3 M) at 25 ° C. was treated with KHMDS (3.9 mL, 0.5 M solution in THF, 1.95 mmol, 1.0 equiv) and the reaction mixture was stirred at reflux for 1 h. The reaction mixture was then cooled to −78 ° C., treated with 3 (0.93 g, 2.35 mmol, 1.2 equiv), warmed to 25° C., and stirred for an additional 30 min.
[0139] The reaction mixture was then treated with saturated aqueous NH4Cl and partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was dried (Na2SO4) and concentrated under reduced pressure. Chromatography (Sio2,5 cm×15 cm, 0-2% EtOAc-hexanes gradient elution) afforded the intermediate as a colorless oil (0.82 g, 1.07 g theoretical, 76.3%): 1H NMR (CDCl3,250 MHz) δ 7.67 (m, 4H, ArH), 7.41 (m, 6H, ArH), 5.34 (m, 2H, CH═CH), 3.65 (m, 5H, CH3OC(O) and CH2OTBDPS), 2.29 (t, 2H, J=7.4 Hz, CH2C(O)OCH3), 2.00 (m, 4H, CH2CH═CHCH2), 1.55 (m, 4H, CH2CH2C(O)OCH3and CH2CH2OTBDPS), 1.29 (b s, 18H, alkyl protons), 1.04 (s, 9H, (CH3)3C).
[0140] 24. 18-T-butyldiphenylsilyloxy-cis-9,10-octadecenoic acid (Compound 100: FIG. 5)
[0141] A solution of Methyl-18-t-butyldiphenysilyloxy-cis-9,10-octadecenoate (0.81 g, 1.47 mmol, 1.0 equiv) in THF-MeOH-H2O (3-1-1 ratio, 7.3 mL, 0.2 M) at 0° C. was treated with LiOH.H2O (0.188 g, 4.48 mmol, 3.0 equiv). The reaction mixture was warmed to 25° C., stirred for 8 h, and then partitioned between EtOAc (100 mL) and H2O (100 mL). The organic layer was washed successively with 10% aqueous HCl (100 mL) and saturated aqueous NaCl (100 mL), dried, and concentrated under reduced pressure. Chromatography (SiO2,5 cm×15 cm, 10-30% EtOAc-hexanes gradient elution) afforded 100 as a colorless oil (0.700 g, 0.790 g theoretical, 88.7%): 1H NMR (CDCl3,250 MHz) δ 7.67 (m, 4H, ArH), 7.41 (m, 6H, ArH), 5.34 (m, 2H, CH═CH), 3.65 (t, 3H, J=6.5 Hz, CH2OTBDPS), 2.34 (t, 2H, J=7.4 Hz, CH2COOH), 2.00 (m, 4H, CH2CH═CHCH2), 1.65-1.50 (m, 4H, CH2CH2COOH and CH2CH2OTBDPS), 1.47-1.23 (m, 18H, alkyl protons), 1.05 (s, 9H, (CH3)3C); FABHRMS (NBA/CsI) m/e 669.2772 (C34H52O3Si+Cs+ requires 669.2740). 25. Synthesis of Compound 101 (FIG. 5)
[0142] Step 1.
[0143] A solution of 100 (1.0 equiv) in CH2Cl2(0.3 M) at 0° C. was treated dropwise with oxalyl chloride (4.0 equiv). The reaction mixture was stirred at 25° C. for 4 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH4OH (2.0 mL). The reaction mixture was then partitioned between EtOAc (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure.
[0144] Step 2.
[0145] A solution of the above step 1 intermediate compound (1.0 equiv) in ether (0.3 M) at 0° C. was treated dropwise with pyridine (8.0 equiv.) followed by trifluoroaceticanhydride (6.0 equiv; Aldrich). The reaction mixture was stirred at 25° C. for 3 h, concentrated under reduced pressure, cooled to 0° C., and treated with saturated aqueous NH4OH (2.0 mL). The reaction mixture was then partitioned between EtOAc (100 mL) and H2O (100 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure.
[0146] Step 3.
[0147] A solution of the above step 2 intermediate compound (1.0 equiv) in THF (0.31 M) was treated with tetrabutylammoniumfluoride (1.0 M solution in THF, 3.0 equiv) and the reaction mixture was stirred at 25° C. for 3 h. The reaction mixture was then partitioned between EtOAc (50 mL) and H2O (50 mL), and the organic layer was dried (Na2SO4) and concentrated under reduced pressure. Product was purified by standard chromatographic conditions and yielded compound 101 in 66% overall yield for the 3 steps.
[0148] 26. Synthesis of Compound 102 (FIG. 5)
[0149] Step 1.
[0150] A solution of 101 (1.0 equiv.) in THF (0.1 M) was treated with triphenylphosphine (2.0 equiv.), followed by diethylazodicarboxylate solution (1.0 THF solution, DEAD, 2.0 equiv., Aldrich) and at 0° C. for 30 minutes. The reaction mixture was concentrated under reduced pressure and washed repeatedly with Et2O (5×10 mL washes). The remaining residue was then solubilized in the minimum volume of CH2Cl2and concentrated under reduced pressure.
[0151] Step 2.
[0152] A solution of the above step 1 compound (1.0 equiv.) in THF (0.10 M) was treated with thiolacetic acid (2.0 equiv.; Aldrich) at 0° C. for 30 minutes. The reaction mixture was concentrated under reduced pressure and washed repeatedly with Et2O (5×10 mL washes). The remaining residue was then solubilized in the minimum volume of CH2Cl2and concentrated under reduced pressure. Product was purified by standard chromatographic conditions and yielded compound 102 in 71% overall yield for the 2 steps.
[0153] 27. Synthesis of Compound 103 (FIGS. 4 & 5)
[0154] Step 1.
[0155] A solution of 102 (1.0 equiv) in MeOH/Water (2:1 mixture, total concentration 0.20 M) at 0° C. was treated with NaOH (3.0 equiv) and stirred for 10 minutes, and then partitioned between EtOAc (100 mL) and water (100 mL). The organic layer was washed successively with 10% aqueous HCl (100 mL) and saturated aqueous NaCl (100 mL), dried, and concentrated under reduced pressure.
[0156] Step 2.
[0157] A solution of the above step 1 compound (1.0 equiv) in aqueous 1N HCl at 0° C. was stirred until the reaction mixuture achieved a pH of 7.0, and then the mixture was partitioned between EtOAc (100 mL) and water (100 mL). The organic layer was washed successively with saturated aqueous NaCl (100 mL), dried, and concentrated under reduced pressure.
[0158] Step 3. A solution of the above step 2 compound (1.0 equiv.) in aqueos 1 mM NaHCO3at 25° C. was treated with Pyridyl disulfide beads (1.1 equiv. Aldrich) and stirred for 2 hours. The beads were subsequently washed with excess saturated NaHCO3(3×), water (3×) and brine (1×). Standard filtration obtained the activated beads (compound 103) which were then packed into the column for affinity chromatography of the enzyme as discussed supra using this CF3-inhibitor linked to activated pyridyl disulphide beads.
[0159] D. Cloning of Cis-9,10-Octadecenoamidase cDNA
[0160] 1. Cis-9,10-Octadecenoamidase cDNA Obtained from Rat Liver mRNA
[0161] To obtain a CDNA clone for cis-9,10-octadecenoamidase from CDNA library generated from rat liver mRNA, degenerate oligonucleotide primers were designed based on the amino acid residue sequence of cis-9,10-octadecenoamidase polypeptide fragment obtained from a trypsin digest. Briefly, the cis-9,10-octadecenoamidase, purified as described above, was subjected to a trypsin digest to form internal polypeptide fragments as performed by Worchester Foundation, Worchester, Pa. The resultant polypeptide fragments were purified by HPLC and seven HPLC fractions showing discrete peptide masses as measured by Matrix-Assisted-Laser-Desorption-Ionization with Time-of-Flight (MALDI TOF, PerSeptive Biosystems Linear Instrument) mass spectrometry were selected for microsequencing. Seven polypeptide fragments were microsequenced having lengths ranging from 12 to 25 amino acid residues as indicated in FIG. 9 indicated by seven discontinuous singly underlined regions in the complete rat cis-9,10-octadecenoamidase amino acid residue sequence. Each peptide possessed the required lysine or arginine residue at its C-terminus indicating that the tryptic digest proceeded with the anticipated selectivity.
[0162] The degenerate oligonucleotide primers were designed to incorporate a unique restriction site into the 5′ ends of the primers that functioned as either forward and the backward primers. The forward primers are also referred to as upstream, sense or 5′ primers. The backward primers are also referred to as downstream, anti-sense or 3′ primers. The restriction sites were incorporated into the polymerase chain reaction (PCR) products to allow for insertion into the multiple cloning site of a sequencing vector as described below.
[0163] The synthesized 5′ and 3′ degenerate oligonucleotides were designed respectively corresponding to portions of sequenced peptides 1 and 2 as shown in FIG. 9 as indicated by the first two discontinuous singly underlined amino acid residue sequences. The degenerate nucleotides are indicated by IUPAC codes N=A, C, G or T and R =A or G. The nucleotide sequence of the 5′ degenerate primer corresponding to peptide 1 was 5′ CGGAATTCGGNGGNGARGGNGC3′ (SEQ ID NO 3) incorporating an EcoRI restriction site and translating into the amino acid sequence GGEGA (SEQ ID NO 4). The nucleotide sequence of the 3′ degenerate primer that corresponded to peptide 2 was 5′ CGGGATCCGGCATNGTRTARTTRTC3′ (SEQ ID NO 33) incorporating an BamHI restriction site and translating into the amino acid sequence DNYTMP (SEQ ID NO 34).
[0164] To amplify regions of cDNA encoding cis-9,10-octadecenoamidase, rat liver mRNA was reversed transcribed into cDNA for use a template in PCR with selected pairs of degenerate oligonucleotide primers described above. PCR was performed under conditions well known to one of ordinary skill in the art with each cycle of 40 total cycles having the temperatures 94° C. for 30 seconds, 60° C. for 45 seconds and 72° C. for 60 seconds.
[0165] Of the cloned PCR fragments, three were selected for sequencing. The three PCR fragments were 350 base pairs (bp), 400 bp and 750 bp. Sequencing of these cis-9,10-octadecenoamidase-encoding cDNA fragments showed that the 750 bp fragment contained the sequences of both the 350 and 400 bp fragments.
[0166] The 350 bp cDNA fragment obtained by PCR was then labeled internally and used as a probe for Northern analysis on electrophoresed rat liver mRNA. The probe hybridized to a fragment approximately 2.5 to 3.0 kilobases (kb) in length, which is the expected size of the cis-9,10-octadecenoamidase mRNA that encodes a 60 kDa protein.
[0167] To isolate a cDNA clone encoding the complete cis-9,10-octadecenoamidase protein, the 350 bp probe was then internally labeled with 32P used to screen a λgtll cDNA library from rat liver mRNA obtained from Clontech (Palo Alto, Calif.). For screening, the amplified 350 bp fragment was first digested with EcoRI and BamHI for directional cloning into a similarly digested pBluescript II SK(−)(Stratagene, La Jolla, CA). The resultant sequence indicated that the 350 bp fragment encoded the peptides 1 and 2 from which the degenerate oligonucleotide primers were designed confirming the accuracy of the PCR and amplification of the desired clone. The methods for cloning the cis-9,10-octadecenoamidase cDNA of this invention are techniques well known to one of ordinary skill in the art and are described, for example, in “Current Protocols in Molecular Biology”, eds. Ausebel et al., Wiley & Sons, Inc., New York (1989), the disclosures of which are hereby incorporated by reference.
[0168] Four positive clones were identified from a screening of 4.5×105plaques. Two clones of 2.7 kb in length and 1 of 2.0 kb in length, were obtained. The partial sequence of one of the 2.7 kb clones, designated p60, indicates that the clone does contain cis-9,10-octadecenoamidase-specific sequences.
[0169] The rat liver cDNA clone designated p60 obtained above has been deposited with American Type Culture Collection (ATCC) on or before Jun. 12, 1996 and has been assigned the ATCC accession number 97605. This deposit was made under the provisions of the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purpose of Patent Procedure and the Regulations thereunder (Budapest Treaty). This assures maintenance of a viable plasmid for 30 years from the date of each deposit. The plasmid will be made available by ATCC under the terms of the Budapest Treaty which assures permanent and unrestricted availability of the progeny of the plasmid to the public upon issuance of the pertinent U.S. patent or upon laying open to the public of any U.S. or foreign patent application, whichever comes first, and assures availability of the progeny to one determined by the U.S. Commissioner of Patents and Trademarks to be entitled thereto according to 35 U.S.C. §122 and the Commissioner's rules pursuant thereto (including 37 CFR §1.14 with particular reference to 886 OG 638). The assignee of the present application has agreed that if the plasmid deposit should die or be lost or destroyed when cultivated under suitable conditions, it will be promptly replaced on notification with a viable specimen of the same plasmid. Availability of the deposit is not to be construed as a license to practice the invention in contravention of the rights granted under the authority of any government in accordance with its patent laws.
[0170] A partial nucleotide sequence of the top strand of the p60 cDNA clone containing 780 nucleotides described above is listed in SEQ ID NO 1 along with the deduced amino acid residue sequence. The encoded amino acid residue sequence is listed separately in SEQ ID NO 2. In order to show the amino acid residue encoded by each triplet codon in the Sequence Listing, a stop codon, TAA, was added at positions 781 to 783 to allow for the coding sequence (CDS) function in the Patentin program used to prepare the Sequence Listing. In other words, the stop codon is artificially inserted into the nucleotide sequence shown in SEQ ID NO 1 to facilitate the translation of the cDNA coding sequence into an amino acid sequence.
[0171] The actual position of the cis-9,10-octadecenoamidase nucleotide position within a complete cDNA clone is evident from the complete cDNA sequence as described below.
[0172] The two largest positive cDNA clones were then cloned into pBluescript II SK(+) and sequenced. One clone encoded a partially processed transcript containing the full coding sequence of the oleamide amidase with an additional 200 bp of intronic sequence. The other clone encoded a fully processed oleamide amidase transcript but fused to the 5′ end of the clone was a 300 bp fragment encoding rRNA. Fusion of the two clones through an internal overlapping HindIII restriction site generated the full-length rat cis-9,10-octadecenoamidase also referred to as fatty acid amide hydrolase abbreviated as FAAH. The clone was sequenced with sequencing primers that were synthesized on a Beckman Oligo1000M Synthesizer.
[0173] The resultant full length rat cDNA FAAH clone, also referred to as rFAAH cDNA, contained 2473 bp, which contained a single 1.73 kb open reading frame encoding 63.3 kDa of protein sequence as shown in FIGS. 10-1 to 10-5. The double-stranded rat FAAH cDNA sequence is available by GenBank with Accession Number U72497. The encoded rat FAAH protein is also referred to as rFAAH protein. The clone contained 50 bp of sequence 5′ to the first ATG designation the start of the open reading frame. The clone also contained 685 bp of 3′ untranslated region between the first stop codon indicating the end of the open reading frame and the poly A tail.
[0174] In FIGS. 10-1 through 10-5, the encoded amino acid residue is positioned directly underneath the second nucleotide of a triplet codon. For example, at the initiation site where ATG encodes methionine (M), the A nucleotide begins at nucleotide position 50 and the G nucleotide is 52. The encoded M is located underneath the T nucleotide at nucleotide position 51. As presented in the figure, thus, the indicated triplet codons are not as indicated. The top and bottom strands of the cDNA sequence are also respectively listed as SEQ ID NOs 35 and 37. The encoded amino acid sequence is shown in with the top strand in SEQ ID NO 35 and again by itself in SEQ ID NO 36.
[0175] Although the 50 bases of nucleotide sequence upstream of the first ATG did not possess an in-frame stop codon, the following several lines of evidence supported the 2.47 kb CDNA encoding the complete oleamide hydrolase protein sequence: 1) The size of the cDNA matched closely the predicted size of the mRNA transcript as estimated by Northern blot (FIG. 12B as discussed below); 2) The sequence surrounding the first ATG possessed the required consensus sequence for eukaryotic translation initiation sites, in particular, an A is present at the −3 position and a G is present at the +4 position; and 3) When transiently transfected with oleamide hydrolase cDNA, COS-7 cells translated a functional protein product that comigrated with affinity isolated oleamide hydrolase on SDS-PAGE (FIG. 12B, lane 1 and discussed below).
[0176] Database searches with the oleamide amidase protein sequence (FAAH) identified strong homology to several amidase enzyme sequences from organisms as divergent as Agrobacterium tumefaciens(Klee et al., Proc. Nat . Acad. Sci., USA,81:1728-1732, 1984), Pseudomonas savastanoi(Yamada et al., Proc. Natl. Acad. Sci., USA,82:6522-6526, 1985); Aspergillus nidulans(Corrick et al., Gene,53:63-71, 1987), Saccharomyces cerevisiae(Chang et al., Nuc. Acids Res.,18:7180, 1990), Caenorhabditis elegans(Wilson et al., Nature,368:32-38, 1994), and Gallus domesticus(Ettinger et al., Arch. Biochem. Biophys.,316:14-19, 1995). These amidases collectively compose a recently defined enzyme family (Mayaux et al., J. Bacteriol.,172:6764-6773, 1990) whose members all share a common signature sequence as shown in FIG. 11. The encoded amino acids beginning at position 215 and extending through 246 of the rat fatty acid amide hydrolase (oleamide hydrolase or FAAH) contain residues that are found in a family of D M amidases. The sequence in the cis-9,10-octadecenoamidase rat protein of this invention has is shown in SEQ ID NO 36 at amino acid positions 215 to 246. The alignment over the amidase signature sequence region of the rat FAAH with several other representative amidases reveals that the signature sequence is completely conserved among the amidase family members. Those amino acids are shown in bold faced type in the figure and the relative amino acid position of the signature sequence in each amidase is given by the numbers just preceding and following the sequence information. The assigned SEQ ID NOs for each of the sequences are listed in the legend to the Figure in Brief Description of the Figures.
[0177] To our knowledge an, oleamide amidase also referred to as FAAH is the first mammalian member of this enzyme family to have been molecularly characterized.
[0178] Hydropathicity plot and transmembrane domain searches (TMpred and PSORT programs) of the rat FAAH sequence were conducted, and each search indicated a strong putative transmembrane domain from amino acids 13-29 (bold type in FIG. 9). The 50 amino acid region surrounding and encompassing the putative transmembrane domain of rat FAAH shares no homology with protein sequences of other amidase family members, indicating that one of the unique modifications of the rat amidase may be its integration into the membrane. Interestingly, additional analysis of the FAAH sequence revealed a polyproline segment, amino acids 307-315 (double underlined in FIG. 9), that contains a precise match from positions 310 to 315 to the consensus class II SH3 domain binding sequence, PPLPXR (SEQ ID NO 38) Feng et al, Science,266:1241-1246, 1994), suggesting that other proteins may interact with FAAH to regulate its activity (Pawson, Nature,373:573-580, 1995) and/or subcellular localization (Rotin et al, EMBO J.,13:4440-4450, 1994).
[0179] Southern and Northern blot analyses were conducted with an internal 800 bp fragment of the rat FAAH CDNA to evaluate the genomic copy number and tissue distribution of FAAH, respectively.
[0180] For the Southern blot, 10 Mg of rat genomic DNA was digested with the indicated restriction enzymes (100 units each) for 12 hours and then run on a 0.8% agarose gel. Rat genomic DNA was first isolated from rat liver as follows: approximately 500 mg of rat liver was shaken overnight at 55° C. in 2 ml of 100 mM Tris (pH 8.0), 0.2% SDS, 200 mM NaCl, and 0.2 mg/ml of proteinase K. The mixture was then spun at 15,000 rpm for 15 minutes and the supernatant was removed and treated with an equal volume of isopropanol. The precipitated genomic DNA was removed, partially dried, and resuspended in water by heating at 55° C. for 4 hours. 10 Mg of the DNA was digested with the indicated restriction enzymes (100 units each) for 12 hours, and then run on a 0.8% agarose gel. The DNA was then transferred under capillary pressure to a GeneScreenPlus hybridization transfer membrane (DuPont NEN) for use in Southern blot analysis. The blot was handled according to manufacturer's (Clontech) guidelines and subjected to the following post-hybridization washes: one 20 minute wash in a solution of 1% SDS and 0.2×SSC (30 mM NaCl, 3.0 mM sodium citrate, pH 7.0) at 25° C., followed by two 20 minute washes in a solution of 0.1% SDS and 0.2×SSC at 65° C. and one additional post-hybridization wash (0.1% SDS, 0.1×SSC, pH 7.0) at 65° C. for 1 hour. The blot was then exposed to X-ray film for 12 hours at −78° C.
[0181] Southern blot studies showed that the FAAH probe hybridized primarily to single DNA fragments using several different restriction digests of the rat genome (FIG. 12A). As expected, two hybridizing bands were observed in the HindIII digested DNA, as the FAAH probe contained an internal HindIII site. These results are most consistent with the FAAH gene being a single copy gene.
[0182] For Northern analyses, blots obtained from Clontech were handled according to manufacturer's guidelines, except that an additional post-hybridization wash with a solution of 0.1% SDS and 0.1×SSC (15 mM NaCl, 1.5 mM sodium citrate, pH 7.0) at 65° C. for 1 hour was conducted to ensure removal of nonspecific hybridization. The resulting blot was exposed to X-ray film for 6 hours at −78° C.
[0183] Northern blot analysis with the FAAH probe identified a single major mRNA transcript of approximately 2.5 kb in size that is most abundant in liver and brain, with lesser amounts present in spleen, lung, kidney, and testes (FIG. 12B). This transcript was not detectable in either heart or skeletal muscle, consistent with previously reported biochemical studies identifying no anandamide hydrolase activity in these two tissues (Deutsch et al, Biochem. Pharmacol.,46:791-796, 1993). The Northern blot also contained low level hybridization of the FAAH cDNA probe to a few larger transcripts present only in those tissues expressing the 2.5 kb transcript as well. These transcripts may be either unprocessed or alternatively spliced forms of the 2.5 kb mRNA. In addition, the regional distribution of the rat FAAH transcript in the rat brain was examined by Northern analysis revealing highest level of the hippocampus and thalamus with lower levels of transcript detectable in other regions of the brain, including olfactory bulb, cortex, cerebellum and pituitary. Preliminary in situ hybridization analysis of rat brain slices has also identified high expression levels for rat FAAH in both hippocampus and hypothalamus. Lastly, Northern analysis of mouse FAAH expression levels at various stages in mouse embryonic development was performed where the mouse FAAH was first observed between days 11 and 15 with levels continuing to increase dramatically from day 15 to 17.
[0184] 2. Cis-9,10-Octadecenoamidase cDNA Obtained from Mouse Liver MRNA
[0185] The mouse homolog of the rat cis-9,10-Octadecenoamidase cDNA was obtained from screening a mouse liver 5′-stretch plus cDNA library (Clontech) using the same conditions as described above for obtaining the rat cDNA with the one exception that the entire rat cDNA (FIG. 10-1 through 10-5) was used as the labeled probe.
[0186] The resultant mouse double-stranded 1959 bp cDNA homolog and encoded amino acid residue is shown in FIG. 13-1 through 13-4 with the ATG start site beginning at nucleotide position 7 indicated with the boxed methionine (M) residue. The stop codon, TGA, is similarly boxed as shown on FIG. 13-4 at nucleotide positions 1744 to 1746 followed by the 3′ untranslated region. The top and bottom strands of the cDNA sequence are also respectively listed as SEQ ID Nos 39 and 41. The encoded amino acid sequence is shown in with the top strand in SEQ ID NO 39 and again by itself in SEQ ID NO 40.
[0187] 3. Cis-9,10-Octadecenoamidase CDNA Obtained from Human Liver mRNA
[0188] A cDNA clone for the human homolog of cis-9,10-octadecenoamidase was similarly obtained as described above for the rat by screening a human liver 5′ stretch plus cDNA library (Clontech) with the exception that the entire rat cDNA prepared above was used as the labeled probed and less stringent hybridization (25% instead of 50% formamide in the manufacturer's recommended hybridization buffer) was employed. Washing conditions also included 2×SSC containing 0.1% SDS at 500C instead of 1×SSC containing 0.1% SDS at 65° C.
[0189] The resultant human double-stranded 2045 bp cDNA homolog and encoded amino acid residue is shown in FIGS. 14-1 through 14-5 with the ATG start site beginning at nucleotide position 36 indicated with the boxed methionine (M) residue. The stop codon, TGA, is similarly boxed as shown on FIG. 14-4 at nucleotide positions 1773 to 1775 followed by the 3′ untranslated region. The top and bottom strands of the cDNA sequence are also respectively listed as SEQ ID Nos 42 and 44. The encoded amino acid sequence is shown in with the top strand in SEQ ID NO 42 and again by itself in SEQ ID NO 43.
[0190] E. Preparation of Expressed Recombinant the Fatty Acid Amide Hydrolase Cis-9,10-Octadecenoamidase:
[0191] For preparing recombinant FAAH proteins for use in this invention, the rat, mouse and human cDNAs obtained above were separately cloned into the eukaryotic expression vector pcDNA3 for transient expression studies in COS-7 cells.
[0192] For preparing the rat, mouse and human FAAH recombinant protein, the corresponding FAAH cDNAs were excised from the Bluescript II vectors and separately ligated into the eukaryotic expression vector, pcDNA3 (Invitrogen, San Diego, Calif.). 100 mm dishes of COS-7 cells were grown at 37° C. to 70% confluency in complete medium (DMEM with L-glutamine, non-essential amino acids, sodium pyruvate and fetal bovine serum). The COS-7 cells were'then washed with serum-free medium and treated with 5 ml of transfection solution (5-6 μg of FAAH-pcDNA3 vector were preincubated with transfectamine (Gibco-BRL) for 30 minutes in 1 ml of serum free medium, then diluted to a final volume of 5 ml with serum free medium). The COS-7 cells were incubated at 37° C. for 5 hours, at which point 10 ml of complete medium was added to the cells and incubation was continued at 37° C. for 12 hours. The transfection solution was then aspirated away from the COS-7 cells, and the cells were incubated in a fresh batch of complete medium for another 24 hours. The COS-7 cells were harvested with a cell scraper, pelleted at low speed, washed twice with 1 mM NaHCO3, and resuspended in 200 μl of 1 mM NaHCO3. The resuspended COS-7 cells were dounce homogenized 12 times and 20 μl of the resulting cell extract was used to assay for oleamide hydrolase activity (assay is detailed above in Section B6) with the results as described below in Section F. Control COS-7 cells were prepared identically except that the pcDNA3 vector used for transfection contained the FAAH cDNA in reverse orientation.
[0193] The resultant expressed recombinant FAAH proteins for rat, human and mouse are then used as described below to assess specificity and enzymatic activity.
[0194] F. Fatty Acid Amide Hydrolase Specifificty and Activity of the Expressed Recombinant Fatty Acid Amide Hydrolases
[0195] As described above, the transfected COS-7 cells were lysed to generate a cell extract for each of the recombinant expressed rat, mouse and human FAAH proteins of this invention.
[0196] While untransfected COS-7 cells contained negligible amounts of oleamide hydrolase activity, COS-7 cells transfected with the rat FAAH cDNA expressed high levels of oleamide hydrolase activity (FIG. 15A). The assay was performed as described in Section B where by TLC the conversion of oleamide to oleic acid was assessed. As shown in FIG. 15A, COS-7 cells transiently tranfected with rat oleamide hydrolase cDNA in expression vector pcDNA 3 shown in lane 3 but not in untransfected COS-7 cells (lane 1) or control transfected cells (lane 2, transfected with pcDNA3 containing the oleamide hydrolase cDNA in reverse orientation), were effective at converting labeled oleamide to oleic acid. Similar results were obtained with COS-7 cells transiently transfected with human oleamide hydrolase as shown in FIG. 16 where the conversion to oleic acid is seen only in lane 2 as compared to control COS-7 cells in lane 1.
[0197] This enzyme activity, like the rat liver plasma membrane oleamide hydrolase activity, was inhibited by trifluoromethyl ketone as evidenced in FIG. 15B as shown in lane 2 of the figure the rat oleamide hydrolase-transfected COS-7 cells in the presence of 50 μM trifluoromethyl ketone as compared to the untreated extract in lane 1.
[0198] To confirm specificity of the expressed recombinant proteins, Western blot analyses with anti-FAAH polyclonal antibodies alone or in the presence of competing peptides were performed. Samples of cell extract from rat FAAH-transfected and untransfected COS-7 cells with approximately equal protein amounts were heated to 65° C. for 10 minutes in loading buffer with 2% SDS and 5% β-mercaptoethanol. The samples indicated above were then run on an 8-16% polyacrylamide gradient Tris-glycine gel, and transferred to nitrocellulose for Western blotting. The nitrocellulose blot was blocked with 5% Blotto in TBS-Tween overnight at 4° C., and then incubated with polyclonal antibodies generated against peptide 2 as previously described (15 μg/ml in TBS-Tween) generated against an internal FAAH peptide sequence for 2 hours at 25° C. The blot was then washed in TBS-Tween (0.1%), incubated with a secondary antibody-horseradish peroxidase conjugate for 30 minutes at 25° C., washed again in TBS-Tween, and developed with Stable Peroxide Solution and Luminol/Enhancer Solution (Pierce). Peptide competition experiments were conducted by preincubating 1000-fold molar excess of the peptide antigen corresponding to peptide 2 as previously described with polyclonal antibodies for 30 minutes prior to addition of antibodies to the blot.
[0199] Western blotting of the rat cDNA transfected COS-7 cell extract with polyclonal antibodies generated against the internal peptide 2 sequence of FAAH showed a 60-65 kDa immunoreactive band that comigrated with affinity-isolated FAAH on SDS-PAGE (FIG. 15C). Untransfected COS-7 cell extract contained no detectable immunoreactive protein band of this size. Additionally, the immunoreactivity of the 60-65 kDa protein was effectively competed away by preincubation of the antibodies with excess peptide antigen (FIG. 15C), while the trace quantities of cross reactive protein observed in both the transfected and untransfected COS-7 cell extracts were not competed by this peptide.
[0200] Previous work suggested that the enzyme activity that hydrolyzes oleamide may be the same activity that converts anandamide (arachidonyl ethanolamide) to arachidonic acid. Therefore, COS-7 cells transfected with the rat FAAH cDNA were assayed for anandamide hydrolase activity. To assess the enzymatic activity of the expressed recombinant fatty acid amide hydrolases of this invention on labeled anandamide, the following enzymatic assay was performed. 14C-anandamide was synthesized as follows: 12.5 μCi (specific activity of 50 μCi/AM) of 14C arachidonic acid (Moravek Biochemicals) was dissolved in 100 μl CH2Cl2, cooled to 0° C., and treated with excess oxalyl chloride. The reaction mixture was stirred at 25° C. for 6 hours, after which time the solvent was evaporated. The remaining residue was cooled to 0° C., treated with a large excess of ethanolamine, and stirred at 25° C. for 15 minutes. The reaction mixture was then partitioned between ethyl acetate and 2 M HCl, and the organic layer was washed with water and then evaporated to dryness. The resulting 14C-anandamide was diluted with unlabeled anandamide to a final specific activity of 5 μCi/μM in ethanol. Approximately 1 μCi of 14C-anandamide and 20 μl of dounce homogenized COS-7 cell extract were used for each anandamide hydrolase assay as detailed above for the oleamide hydrolase assays. Briefly, FAAH hydrolysis assays were conducted in triplicate with 100 μM substrate, 35 μg of rat transfected COS-7 cell protein for 5 minutes at 37° C. (except in the case of stearic amide, where due to low solubility, 20 μM substrate comparison to oleamide were conducted). Products were separated on TLC as described previously, scraped into scintillation fluid, and radioactivity was quantitated by scintillation counting. Substrate hydrolysis in the presence of equal amounts of untransfected COS-7 cell protein extract served as background control in all cases and was substracted from FAAH hydrolysis rates to give the data as presented below.
[0201] The results of the anandamide assays showed that while untransfected COS-7 cells contained negligible quantities of anandamide hydrolase activity, transfected COS-7 cells produced high levels of anandamide hydrolase activity (FIG. 17). Thus, FAAH has the capacity to hydrolyze both oleamide and anandamide, indicating that the amidase may act as a general degradative enzyme for the fatty acid amide family of signaling molecules. The substrate promiscuity of FAAH is reminiscent of the monoamine oxidase enzymes which serve to oxidize a variety of amine-containing neurotransmitters.
[0202] To further assess the substrate specificity spectrum of enyzmatic hydolytic activity of the recombinant expressed proteins of this invention, other 14C-labeled fatty acid amides were synthesized as described in Section B6 and above for 14C-oleamide, with the exception of anandamide as described.
[0203] The results showed that while recombinant expressed rat FAAH catalyzes the hydrolysis of oleamide and anandamide at approximately equal rates, FAAH does discriminate among fatty acid amides, as FAAH hydroylzes other representative fatty acid amides, including myristic amide, palmitic amide and stearic amide at a significantly reduced rate as compared to that seen with oleamide or anandamide as shown in Table 1 below. Where indicated in the table the anandamide and oleamide hydrolysis rates are considered to be 100% of FAAH activity to which other fatty acid amide hydrolysis rates are compared.
[0204] Comparable assays are performed with the mouse and human recombinant homologs to the rat enzyme as used above.
[0205] Thus, as shown above, the rat FAAH enzyme was not without substrate preference, albeit it did exhibit activity against a number of amide substrates. The degree to which FAAH showed substrate selectivity is best exemplified by the nearly twenty fold rate difference between the enzyme's hydrolysis of oleamide and steric amide, two compounds that only differ by a single degree of unsaturation at the Δ9 position. This pattern was also confirmed with assays with the inhibitor trifluoromethyl ketone that was a twenty fold stronger inhibitor of FAAH than for the corresponding trifluoromethyl ketone analog of stearic amide. Thus, FAAH significantly favors the bent alkyl chain of oleamide over the straight alkyl chain of stearic amide.
[0206] A deletion mutant for generating a soluble form of the FAAH molecules of this invention was also prepared. A construct was created in which the putative transmembrane domain was deleted resulting in a truncated FAAH beginning at amino acid residue 30 of the encoded protein rather than 1. To prepare this construct, the following primers were designed for PCR amplification of the 5′ end of rat FAAH cDNA lacking the first 140 bp encoding the amino terminal 30 amino acids of FAAH. The 5′ and 3′ primers had the respective nucleotide sequences 5′GCGGTACCATGCGATGGACCGGGCGC3′ (SEQ ID NO 45) encoding amino acids 30-35 and containing a KpnI site and an artificial stop codon and 5′GGTCTGGCCAAAGAGAGG3′ (SEQ ID NO 46) where its reverse complement encodes amino acids 199-204.
[0207] The amplified transmembrane deleted rat FAAH cDNA fragment was then digested with the appropriate restriction enzymes (KpnI and HindIII) and cloned into the similarly digested FAAH-pBluescript vector replacing the original cDNA 5′ end. The deleted construct was confirmed by sequencing and then excised and transferred to pcDNA3 for expression studies as described herein.
[0208] For expression, the transfected COS-7 cell extract was separated into soluble and membrane fractions as follows: the extract was spun at 2500 rpm for 5 minutes at 25° C. and the supernatant was transferred to an airfuge tube and spun in an ultracentrifuge (30 psi for 40 minutes at 4° C.) for preparing soluble supernatant. The pellet contained the membrane bound fraction that was then resuspended in a volume of 1 mM NaHCO3equal to the volume of the supernatant.
[0209] The transmembrane-deleted expressed recombinant FAAH was functional in COS-7 cell expression assays as described above. The mouse and human transmembrane truncation homologs of the rat cDNA are similarly prepared and used in practicing this invention.
[0210] Given the increasing number of studies demonstrating biological activities for various members of the fatty acid amide family of signaling molecules, the discovery of a family of fatty acid amide hydrolases (FAAH) having homology between rat, mouse and human as described herein provides a valuable invention for ongoing studies dedicated to understanding the regulation, mechanism, and pharmacology of the metabolic process that inactivates the fatty acid amides. In addition, the cloned FAAH gene in conjunction with potent FAAH inhibitors provides the ability in both elucidating the physiological pathways affected by the fatty acid amide family and developing systematic approaches towards the pharmacological intervention of these biological processes.
Claims
What is claimed is:
1. An isolated and purified polypeptide that has the amino acid residue sequence shown in SEQ ID NO 36.
2. The polypeptide of claim 1 that hydrolyzes myristic amide, palmitic amide and stearic amide.
3. An isolated and purified polypeptide that has the amino acid residue sequence shown in SEQ ID NO 40.
4. The polypeptide of claim 3 that hydrolyzes myristic amide, palmitic amide and stearic amide.
5. An isolated and purified polypeptide that has the amino acid residue sequence shown in SEQ ID NO 43.
6. The polypeptide of claim 5 that hydrolyzes myristic amide, palmitic amide and stearic amide.
Patent Citations (1)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| US4165258 | 1979-08-01 | Pye et al. | Applicant |
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