Cholesterol 7 alpha-hydroxylase from human liver: partial purification and reconstruction into defined phospholipid-cholesterol vesicles

J Lipid Res. 1981 Jul;22(5):872-6.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cholesterol / metabolism
  • Cholesterol 7-alpha-Hydroxylase / isolation & purification
  • Cholesterol 7-alpha-Hydroxylase / metabolism*
  • Cytochrome P-450 Enzyme System / metabolism
  • Humans
  • Liposomes
  • Microsomes, Liver / enzymology*
  • Phospholipids
  • Steroid Hydroxylases / metabolism*


  • Liposomes
  • Phospholipids
  • Cytochrome P-450 Enzyme System
  • Cholesterol
  • Steroid Hydroxylases
  • Cholesterol 7-alpha-Hydroxylase