title: Cumene hydroperoxide-supported demethylation reactions catalyzed by cytochrome P450 2B4 lacking the NH2-terminal sequence.
abstract: Catalytic activities of cytochrome P450 2B4 lacking NH2-terminal amino acids 2-27 (wt Delta2B4) and that of truncated 2B4 containing a Pro to Ser mutation at position 221 were examined in a system supported by cumene hydroperoxide. Demethylation activities of either truncated 2B4 with N-methylaniline, N,N-dimethylaniline, and d-benzphetamine were lower than those of liver microsomal 2B4, whereas the rate of 1-phenylethanol oxidation to acetophenone catalyzed by liver microsomal and truncated 2B4 enzymes was nearly the same. The Km and Vmax values for cumene hydroperoxide in the demethylation of N-methylaniline by wt Delta2B4 were 20% and 28%, respectively, of those obtained for 2B4. The reaction with wt Delta2B4 displayed a lesser dependence on phospholipid than did that with 2B4, and a complex relationship between activity and substrate concentration. The results suggest that the NH2-terminal region contributes to interaction of oxidant, substrate, and phospholipid in cumene hydroperoxide-supported reactions catalyzed by cytochrome P450 2B4.
authors.affiliation: Department of Chemistry, Eastern Michigan University, Ypsilanti, Michigan, 48197, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: S J
authors.initials: SJ
authors.lastname: Pernecky
mesh_terms: D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001555:Benzene Derivatives / Q000378:metabolism*; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D006900:Hydroxylation; D008745:Methylation; D008862:Microsomes, Liver / Q000201:enzymology; D010713:Phosphatidylcholines / Q000378:metabolism; D011817:Rabbits; D017384:Sequence Deletion; D013250:Steroid Hydroxylases / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D000814:Aniline Compounds; D001555:Benzene Derivatives; D010713:Phosphatidylcholines; C015153:1,2-dilauroylphosphatidylcholine; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C050356:steroid 15-alpha-hydroxylase; C007164:cumene hydroperoxide; C021313:methylaniline