The administration of spironolactone, a diuretic steroid, is known to cause a depletion of microsomal cytochrome P-450 in those tissues which have a high activity of steroid 17a-hydroxylase. In this paper, studies are presented to indicate that the sulfur atom located at the carbon 7-a position on the spironolactone molecule is required for the loss of the heme and apoproteins of adrenal or tes...

Components of the hepatic microsomal P-450 hemoprotein electron transfer system (TPNH-cytochrome c reductase and P-450 hemoprotein) and the microsomal cytochrome b5 electron transfer system (DPNH-cytochrome bs reductase and cytochrome bS) were solubilized using Triton N-101 and glycerol, and separated using DEAE-cellulose chromatography. Microsomal aniline hydroxylase activity was reconstituted...

Cytochrome P-450 catalysing 25-hydroxylation of vitamin D3 was purified from pig kidney microsomes. The enzyme fraction contained 7 nmol of cytochrome P-450/mg of protein and showed only one protein band with an apparent Mr of 50,500 upon SDS/polyacrylamide-gel electrophoresis. The purified cytochrome P-450 catalysed 25-hydroxylation of vitamin D3 up to 1,000 times more efficiently, and 25-hydr...

Isolated microsomes catalyze an NADPH-dependent oxidation of typical hydroxyl radical scavenging agents. To determine which microsomal components participate in the oxidation of the scavengers, experiments were carried out with purified NADPH-cytochrome P-450 reductase and cytochrome P-450 isolated from phenobarbital-treated rats. The production of ethylene from 4-ketothiomethylbutyrate or of f...

In vivo administration of the alcohol dehydrogenase inhibitor pyrazole induces a cytochrome P-450 isozyme. The pyrazole-inducible cytochrome P-450 has been purified from rat livers to electrophoretic homogeneity and its biochemical, spectral, and immunological properties characterized. The final preparation had a specific content of 11 nmol of cytochrome P-450/mg of protein. A single band with ...

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 rep...