The functional size of acyl-coenzyme A (CoA):cholesterol acyltransferase and acyl-CoA hydrolase as determined by radiation inactivation.
Frozen rat liver microsomes and rough endoplasmic reticulum were irradiated with high energy electrons. The surviving enzymatic activity of acyl-CoA:cholesterol acyltransferase and activity for esterification of 25-hydroxycholesterol decreased as a simple exponential function of radiation exposure, leading to a target size of 170-180 kDa. The loss of acyl-CoA hydrolase activity with a radiation dose was complex and resolved as a 45-kDa enzyme associated with a large inhibitor. It is interpreted that acyl-CoA hydrolase is the acyl-CoA-binding component and the inhibitor is the cholesterol-binding component of acyl-CoA:cholesterol acyltransferase.
Billheimer
J T
JT
Medical Products Division, E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware 19880-0400.
Cromley
D A
DA
Kempner
E S
ES
D000818:Animals; D001665:Binding Sites; D002784:Cholesterol / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology* / Q000528:radiation effects; D008970:Molecular Weight; D010170:Palmitoyl-CoA Hydrolase / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000528:radiation effects; D051381:Rats; D011919:Rats, Inbred Strains; D002785:Sterol O-Acyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000528:radiation effects; D013869:Thiolester Hydrolases / Q000378:metabolism*
D002784:Cholesterol; D002785:Sterol O-Acyltransferase; D013869:Thiolester Hydrolases; D010170:Palmitoyl-CoA Hydrolase