Partial Purification and Characterization of Cholesterol 7α-Hydroxylase from Guinea Pig

NAKAI Taketomi

Hiroshima Journal of Medical Sciences

[PISSN] 0018-2052

[EISSN] 2433-7668

[NCID] AA00664312

Cholesterol 7α-hydroxylase (cholesterol, NADPH: oxygen oxidoreductase, 7α-xhydroxylating, EC 1.14.13.17), was partially purified from liver microsomes of guinea pig. The purified sample showed a specific activity of 1. 76 nmol/min/mg of protein and a turnover number of 2.3 nmol/min/nmol of cytochrome P-450, which were 100 times as high as respective values of microsomes. Cholesterol 7α-hydroxy lase activity was reconstituted from the partially purified cytochrome P-450, NADPH-cytochrome P-450 reductase, dilauroylglyceryl-3-phosphorylcholine and the NADPH generating system. The reconstituted system showed an absolute requirement for cytochrome P-450, NADPH-cytochrome P-450 reductase and NADPH. The apparent Km value for cholesterol in the reconstituted system was 33 μM and Vmax was 3.4 nmol/min/mg of protein. Cholesterol 7α-hydroxylase activity was significantly inactivated by iodoacetamide and p-chloromercuribenzoate, but not either by aminoglutethimide or by metyrapone.

Cholesterol 7α-hydroxylase

Guinea pig

Cholesterol

医学 [ 490 ]

英語

Hiroshima Journal Medical Press

[ISSN] 0018-2052

[NCID] AA00664312

[PMID] 3115919