Rational Design of Fatty Acid Amide Hydrolase Inhibitors That Act by Covalently Bonding to Two Active Site Residues

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• 作者：Katerina Otrubova ; Monica Brown ; Michael S. McCormick ; Gye W. Han ; Scott T. O鈥橬eal ; Benjamin F. Cravatt ; Raymond C. Stevens ; Aron H. Lichtman ; Dale L. Boger
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：April 24, 2013
• 年：2013
• 卷：135
• 期：16
• 页码：6289-6299
• 全文大小：589K
• 年卷期：v.135,no.16(April 24, 2013)
• ISSN：1520-5126

文摘

The design and characterization of 伪-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 伪-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鈥? h time course monitored.