Cholesterol 7 alpha-hydroxylase from human liver: partial purification and reconstruction into defined phospholipid-cholesterol vesicles.
Cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme for bile acid synthesis, was shown to be copurified with human liver microsomal cytochrome P-450. When these cytochrome P-450 species were reconstituted in phospholipid-cholesterol vesicles together with NADPH-cytochrome P-450 reductase, high cholesterol 7 alpha-hydroxylase activity was obtained in the presence of NADPH. The activity represented a twofold enrichment relative to cytochrome P-450 and 43-fold enrichment relative to total microsomal protein. Availability of such a preparation will allow further characterization of the enzyme and will also allow studies of its mechanisms of regulation.
D002784:Cholesterol / Q000378:metabolism; D002790:Cholesterol 7-alpha-Hydroxylase / Q000302:isolation & purification / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D006801:Humans; D008081:Liposomes; D008862:Microsomes, Liver / Q000201:enzymology*; D010743:Phospholipids; D013250:Steroid Hydroxylases / Q000378:metabolism*
D008081:Liposomes; D010743:Phospholipids; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol; D013250:Steroid Hydroxylases; D002790:Cholesterol 7-alpha-Hydroxylase