Purification and characterization of four catalytically active testosterone 6 beta-hydroxylase P-450s from rat liver microsomes: comparison of a novel form with three structurally and functionally related forms.

摘要: Four microsomal cytochrome P-450s (P-450), all of which are active testosterone 6 beta-hydroxylases, were purified to electrophoretic homogeneity from livers phenobarbital-treated (P-4506 beta-1 and P-4506 beta-3) or dexamethasone-treated adult male rats beta-2 beta-4). Purified beta-1, beta-2, beta-3, beta-4 had apparent molecular weights 52,000, 51,000, 52,500 as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Absolute spectra revealed that four P-450 forms characteristic low-spin spectral patterns in their fully oxidized states. beta-3 displayed the reduced carbonyl complex with lambda max at 447 nm. showed 446 448 nm, respectively. Antibodies raised against each recognized forms, although differences observed respect extents cross-reactivities on Western blots. Form-specific peptide fragments also detected among proteins after partial protease-digestion. was identical first 26 residues NH2-terminal amino acid sequence, but differed 13 beta-2. The amino-terminal sequence unique not those any rat previously reported. This form untreated induced treatment dexamethasone, phenobarbital.(ABSTRACT TRUNCATED AT 250 WORDS)