title: Cytochrome P-450 in human liver microsomes: high-performance liquid chromatographic isolation of three forms and their characterization.
abstract: Three forms of cytochrome P-450, designated as P-450-HM1, P-450-HM2, and P-450-HM3, were isolated from human liver microsomes using high-performance liquid chromatography (HPLC) techniques. Each purified preparation showed a single protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). From the results of SDS-PAGE, the molecular weights of P-450-HM1, P-450-HM2, and P-450-HM3 were estimated to be 51,000, 54,000, and 52,000, respectively. The oxidized absolute spectra of these three forms of cytochrome P-450 showed Soret absorption peaks at around 417 nm, indicating that these forms were in the low spin state. In a reconstituted system, P-450-HM1 showed the highest catalytic activities of nifedipine and (S)- or (R)-nilvadipine oxidases. The same form showed higher activities of testosterone 6 beta-hydroxylase and progesterone 6 beta- and 16 alpha-hydroxylases. P-450-HM2 showed high N-demethylase activities for benz-phetamine and aminopyrine, and also showed the highest activity of testosterone 16 beta-hydroxylase among the three forms, while it did not show detectable activities of testosterone 6 beta-hydroxylase and progesterone 6 beta- and 16 alpha-hydroxylases. Anti-P-450-HM1 immunoglobulin G (IgG), but not anti-P-450-HM2 IgG, inhibited the activities of testosterone 6 beta-hydroxylase and nifedipine and nilvadipine oxidases in human liver microsomes. Anti-P-450-HM1 IgG was also inhibitory against progesterone 6 beta- and 16 alpha-hydroxylases.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Division of Analytical Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University.
authors.forename: M
authors.initials: M
authors.lastname: Komori
authors.forename: T
authors.initials: T
authors.lastname: Hashizume
authors.forename: H
authors.initials: H
authors.lastname: Ohi
authors.forename: T
authors.initials: T
authors.lastname: Miura
authors.forename: M
authors.initials: M
authors.lastname: Kitada
authors.forename: K
authors.initials: K
authors.lastname: Nagashima
authors.forename: T
authors.initials: T
authors.lastname: Kamataki
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008862:Microsomes, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight
chemical_list: D003577:Cytochrome P-450 Enzyme System