Cytochrome P450-dependent desaturation of lauric acid: Isoform selectivity and mechanism of formation of 11-dodecenoic acid

摘要: Abstract Cytochrome P450-catalyzed desaturation reactions have been reported infrequently in the literature. Previously, we documented formation of terminal olefinic metabolite valproic acid by various members CYP2B and CYP4B sub-families. However, despite extensive use fatty substrates drug metabolism studies, other examples at non-activated carbon centers are lacking. The goals present studies were to determine whether archetypal P450 substrate, lauric (dodecanoic acid; DDA), also undergoes reactions, identify specific rabbit isoforms which catalyze this reaction examine its mechanism. A highly sensitive, capillary GC/MS assay was developed separate quantitate trimethylsilyl derivatives 11-ene-DDA, cis- trans-10-ene-DDA trans-9-ene-DDA. Among all these potential metabolites, only 11-ene-DDA formed a significant rate liver microsomes. NADPH-dependent, induced markedly acetone pre-treatment, but not phenobarbital, rifampin or Arochlor 1254. Studies with seven purified, reconstituted showed that most rapid rates obtained CYP2E1, CYP4A5/7 CYP4B1. Non-competitive, intermolecular isotope effect experiments, conducted [12,12,12-2H3]DDA [11,11-2H2]DDA, demonstrated further CYP4B1-mediated DDA is initiated removal hydrogen atom from ω-1 rather than ω position.