Mitochondrial w-Hydroxylation of Cholesterol Side Chain

摘要: Abstract The mitochondrial fraction of rat liver homogenate catalyzed the conversion cholesterol into 5-cholestene-3β,25-diol and 5-cholestene-3β,26-diol in presence an NADPH-generating system oxygen. 5-Cholestene-3β,26-diol was predominant product. 26-Hydroxylation much more efficient with than NADPH alone, it shown that isocitrate generating responsible for most stimulation. Addition Mg2+ increased both NADPH- isocitrate-dependent 26-hydroxylation, at high concentrations 26-hydroxylation about same as isocitrate. Ca2+ NADPH-dependent but not 26-hydroxylation. NADH NADH-generating systems could replace or system. However, together ATP stimulated reaction efficiently, probably due to energy-dependent intramitochondrial transhydrogenation. Citrate were found stimulate efficiently other citric acid cycle intermediates regardless whether present absent. Mitochondrial inhibited by p-hydroxymercuribenzoate. Rotenone, potassium cyanide, dinitrophenol had little no effect on Hg2+, Zn2+, Cu2+, Fe3+ 0.1 mm concentration strongly. Experiments sonically disrupted mitochondria supported contention 26-hydroxylase mainly bound inner membranes. 18O2 2H2O showed 25- well oxygen incorporated is derived from molecular