Human liver debrisoquine 4-hydroxylase: test for specificity toward various monooxygenase substrates and model of the active site.

Polyclonal antibodies raised toward a debrisoquine 4-hydroxylating cytochrome P-450 species purified from rat liver (P-450UT-A) were used to determine which monooxygenase reactions are linked to debrisoquine hydroxylation in human liver. Anti P-450UT-A did not inhibit the oxidation of dimethylnitrosamine, morphine, diazepam, vinylidene chloride, trichloroethylene, benzo(a)pyrene and its 7.8-dihydrodiol, but was inhibitory for the hydroxylation of debrisoquine, (+/-)-bufuralol, lasiocarpine and monocrotaline. A model interpreting the substrate specificity of the human liver enzyme is presented.