4j5p
Crystal Structure of a Covalently Bound alpha-Ketoheterocycle Inhibitor (Phenhexyl/Oxadiazole/Pyridine) to a Humanized Variant of Fatty Acid Amide HydrolaseCrystal Structure of a Covalently Bound alpha-Ketoheterocycle Inhibitor (Phenhexyl/Oxadiazole/Pyridine) to a Humanized Variant of Fatty Acid Amide Hydrolase
Structural highlights
FunctionFAAH1_RAT Degrades bioactive fatty acid amides like oleamide, the endogenous cannabinoid, anandamide and myristic amide to their corresponding acids, thereby serving to terminate the signaling functions of these molecules. Hydrolyzes polyunsaturated substrate anandamide preferentially as compared to monounsaturated substrates (By similarity). Publication Abstract from PubMedThe design and characterization of alpha-ketoheterocycle fatty acid amide hydrolase (FAAH) inhibitors are disclosed that additionally and irreversibly target a cysteine (Cys269) found in the enzyme cytosolic port while maintaining the reversible covalent Ser241 attachment responsible for their rapid and initially reversible enzyme inhibition. Two alpha-ketooxazoles (3 and 4) containing strategically placed electrophiles at the C5 position of the pyridyl substituent of 2 (OL-135) were prepared and examined as inhibitors of FAAH. Consistent with the observed time-dependent noncompetitive inhibition, the cocrystal X-ray structure of 3 bound to a humanized variant of rat FAAH revealed that 3 was not only covalently bound to the active site catalytic nucleophile Ser241 as a deprotonated hemiketal, but also to Cys269 through the pyridyl C5-substituent, thus providing an inhibitor with dual covalent attachment in the enzyme active site. In vivo characterization of the prototypical inhibitors in mice demonstrates that they raise endogenous brain levels of FAAH substrates to a greater extent and for a much longer duration (>6 h) than the reversible inhibitor 2, indicating that the inhibitors accumulate and persist in the brain to completely inhibit FAAH for a prolonged period. Consistent with this behavior and the targeted irreversible enzyme inhibition, 3 reversed cold allodynia in the chronic constriction injury model of neuropathic pain in mice for a sustained period (>6 h) beyond that observed with the reversible inhibitor 2, providing effects that were unchanged over the 1-6 h time course monitored. Rational design of Fatty Acid amide hydrolase inhibitors that act by covalently bonding to two active site residues.,Otrubova K, Brown M, McCormick MS, Han GW, O'Neal ST, Cravatt BF, Stevens RC, Lichtman AH, Boger DL J Am Chem Soc. 2013 Apr 24;135(16):6289-99. doi: 10.1021/ja4014997. Epub 2013 Apr, 12. PMID:23581831[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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