P-450 HFLa, a form of cytochrome P-450 purified from human fetal livers, is the 16 alpha-hydroxylase of dehydroepiandrosterone 3-sulfate.
In a reconstituted system containing NADPH, dilauroyl-L-3-phosphatidylcholine, and NADPH-cytochrome P-450 reductase purified from rat liver microsomes, cytochrome P-450 (P-450 HFLa) purified from human fetal livers catalyzed the 16 alpha-hydroxylation of dehydroepiandrosterone 3-sulfate (DHEA-sulfate). Addition of cytochrome b5 purified from rat liver microsomes to the reconstituted system resulted in a remarkable increase in the hydroxylase activity. The level of P-450 HFLa in liver homogenates from human fetuses highly correlated with the activity of DHEA-sulfate 16 alpha-hydroxylase. Antibodies to P-450 HFLa inhibited the 16 alpha-hydroxylation of DHEA-sulfate in a dose-dependent manner. The NH2-terminal amino acid sequence of P-450 HFLa was similar to that of P-450NF (Beaune, P. H., Umbenhauer, D. R., Bork, R. W., Lloyd, R. S., and Guengerich, F. P. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 8064-8068). We conclude that P-450 HFLa is a form of cytochrome P-450 involved in the 16 alpha-hydroxylation of DHEA-sulfate.
Kitada
M
M
Faculty of Pharmaceutical Sciences, Chiba University, Japan.
Kamataki
T
T
Itahashi
K
K
Rikihisa
T
T
Kanakubo
Y
Y
D000595:Amino Acid Sequence; D000936:Antigen-Antibody Complex; D001189:Aryl Hydrocarbon Hydroxylases; D065727:Cytochrome P-450 CYP2C8; D065729:Cytochrome P-450 CYP2C9; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D000072467:Cytochrome P450 Family 2; D003573:Cytochrome b Group / Q000378:metabolism; D015786:Cytochromes b5; D005333:Fetus; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007074:Immunoglobulin G; D007700:Kinetics; D008099:Liver / Q000196:embryology / Q000201:enzymology*; D039181:Steroid 16-alpha-Hydroxylase
D000936:Antigen-Antibody Complex; D003573:Cytochrome b Group; D007074:Immunoglobulin G; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C450279:CYP2C11 protein, rat; C450259:CYP2C8 protein, human; D065727:Cytochrome P-450 CYP2C8; D000072467:Cytochrome P450 Family 2; D039181:Steroid 16-alpha-Hydroxylase