title: Specific inactivation of hepatic fatty acid hydroxylases by acetylenic fatty acids.
abstract: The terminal acetylenic analogue of lauric acid, 11-dodecynoic acid (11-DDYA), specifically inactivates hepatic cytochrome P-450 enzymes that catalyze omega- and omega-1-hydroxylation of lauric acid. The inactivation, as required for a suicidal process, is NADPH- and time-dependent and follows pseudo-first order kinetics. In contrast, 11-DDYA causes no measurable change in the spectroscopically-measured concentration of cytochrome P-450 or in the N-demethylation of benzphetamine or N-methyl p-chloroaniline. 10-Undecynoic acid is as effective a suicide substrate for fatty acid hydroxylases as 11-DDYA but 11-dodecenoic acid is much less effective. 11-DDYA is able to completely inhibit omega-hydroxylation but suppresses no more than 50% of omega-1-hydroxylation despite the fact that both activities are completely inactivated by 1-aminobenzotriazole. At least three hepatic cytochrome P-450 fatty acid hydroxylases, one omega-hydroxylase and two omega-1-hydroxylases, are required by these results. The construction of suicide substrates that specifically inactivate cytochrome P-450 fatty acid hydroxylases provides a new experimental probe of the physiological role of this process.
mesh_terms: D000818:Animals; D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000138:chemical synthesis / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors*; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship
chemical_list: D005231:Fatty Acids, Unsaturated; C040948:11-dodecynoic acid; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D042926:Cytochrome P-450 CYP4A; D010089:Oxidoreductases, N-Demethylating