Catalytic properties of the purified rat hepatic cytosolic cholesteryl ester hydrolase.
The purified enzyme hydrolyzed cholesteryl oleate, cholesteryl linoleate, and triolein at similar rates over a broad range of concentrations. Hydrolytic activity was relatively low with p-nitrophenyl acetate, but much higher with PNP-esters of the more lipophilic C4-C18 fatty acids, in sharp contrast to microsomal esterases which hydrolyze PNP-acetate more efficiently. Zn2+, Cu2+, Cd2+, Hg2+, and phenylmethylsulfonyl fluoride inhibited, whereas N-ethyl maleimide and iodoacetamide stimulated activity of the pure enzyme. Limited trypsin digestion selectively inhibited cholesteryl esterase activity with retention of activity toward PNP-octanoate, suggesting involvement of a trypsin-labile loop in the lipophilic substrate binding pocket.
Natarajan
R
R
Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond 23298-0614, USA.
Ghosh
S
S
Grogan
W
W
D000818:Animals; D002384:Catalysis; D002788:Cholesterol Esters / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006868:Hydrolysis; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D002787:Sterol Esterase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity; D013656:Taurocholic Acid / Q000494:pharmacology
D002788:Cholesterol Esters; D004791:Enzyme Inhibitors; D013656:Taurocholic Acid; D002787:Sterol Esterase