[Effects of detergents on neutral cholesterol esterase from porcine aorta]

Effects of detergents on hydrolysis of cholesteryl-14C-oleate by porcine aorta extracts were studied. Digitonin, cetyl pyridinium chloride and sodium taurocholate inhibited the activity of cholesterolesterase, sodium cholate enhanced slightly the hydrolysis and Triton X-100 exhibited a considerable stimulating effect. After chromatography of aorta extracts on Bio-Gel A-1.5 m two cholesterolesterase fractions were obtained with molecular weight of about 200,000 and above 1 500 000, respectively; the first fraction was active only in presence of Triton X-100 and the second--hydrolysed cholesteryl-14C-oleate both in presence and absence of the detergent. As a result of treatment of aorta extracts with digitonin (0.4%), the Triton-dependent low molecular fraction of cholesterolesterase was obtained. Since the molecular weight of the enzyme fraction was about 20,000 (as shown by elution profiles), the activating effect of Triton on cholesterolesterase appears to be not due to disaggregation of the enzyme of to destruction of the membrane-enzyme complexes.