title: Inhibition of reconstituted vitamin D3 25-hydroxylase by a protein fraction from rat liver microsomes.
abstract: A cytochrome P-450 fraction, containing vitamin D3 25-hydroxylase activity after reconstitution, was prepared from rat liver microsomes. The 25-hydroxylase activity increased considerably upon purification. A protein fraction isolated from the microsomes during the preparation markedly inhibited the reconstituted vitamin D3 25-hydroxylase activity. The inhibition was dependent on the amount of protein and completely reversed by heat treatment.
mesh_terms: D000818:Animals; D053493:Cholestanetriol 26-Monooxygenase; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D011506:Proteins / Q000302:isolation & purification / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013250:Steroid Hydroxylases / Q000037:antagonists & inhibitors*
chemical_list: D011506:Proteins; D012710:Serum Albumin, Bovine; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D053493:Cholestanetriol 26-Monooxygenase