title: Significance of cytochrome P-450 (P-450 HFLa) of human fetal livers in the steroid and drug oxidations.
abstract: The purpose of this study was to clarify the pharmacological and physiological significance of P-450 HFLa. Thus, correlations between cytochrome P-450 (P-450 HFLa) level and different monooxygenase activities were investigated in liver homogenates from human fetuses. Poor correlation was seen between P-450 HFLa level and the activity of benzphetamine N-demethylation or aniline hydroxylation. In contrast, the content of P-450 HFLa was highly correlated with the activity of benzo(a)pyrene hydroxylation, 7-ethoxycoumarin O-deethylation or testosterone 6 beta-hydroxylation. In microsomes from human adult livers, a moderate relationship was also observed between testosterone 6 beta-hydroxylation and P-450 HFLa level. Furthermore, antibodies to P-450 HFLa inhibited testosterone 6 beta-hydroxylase activity in fetal and adult livers to similar extents. We conclude that P-450 HFLa is a form of cytochrome P-450 which catalyzes testosterone 6 beta-hydroxylation and limited drug oxidations in human fetal and adult livers.
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase; D000815:Aniline Hydroxylase / Q000378:metabolism; D000906:Antibodies; D001189:Aryl Hydrocarbon Hydroxylases; D001579:Benzopyrene Hydroxylase / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000196:embryology* / Q000201:enzymology; D010084:Oxidation-Reduction; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism; D011247:Pregnancy; D013250:Steroid Hydroxylases / Q000378:metabolism
chemical_list: D000906:Antibodies; D007527:Isoenzymes; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D013250:Steroid Hydroxylases; D015660:7-Alkoxycoumarin O-Dealkylase; D000815:Aniline Hydroxylase; D001579:Benzopyrene Hydroxylase; D001189:Aryl Hydrocarbon Hydroxylases; C019781:benzphetamine N-demethylase; C022724:testosterone 7-alpha-hydroxylase, hamster; D010089:Oxidoreductases, N-Demethylating