Purification, characterization and modulation of a microsomal carboxylesterase in rat liver for the hydrolysis of acyl-CoA

• Published in: Biochemical journal Vol. 295; no. 1; pp. 81 - 86
• Main Authors: MUKHERJEE, J. J, JAY, F. T, CHOY, P. C
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 01.10.1993
• Subjects: Acyl Coenzyme A - metabolism; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Carboxylesterase; Carboxylic Ester Hydrolases - drug effects; Carboxylic Ester Hydrolases - metabolism; Enzyme Activation; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydrolases; Hydrolysis; Isoelectric Point; Kinetics; Microsomes, Liver - enzymology; Molecular Weight; Palmitoyl Coenzyme A - metabolism; Palmitoyl-CoA Hydrolase - drug effects; Palmitoyl-CoA Hydrolase - metabolism; Phospholipids - pharmacology; Rats; Rats, Sprague-Dawley; Substrate Specificity; Purification; Rat; Enzyme; Liver; Rodentia; Phospholipid; Esterases; Carboxylesterase; Carboxylic ester hydrolases; Vertebrata; Mammalia; Enzymatic activity; Hydrolases; Physicochemical properties
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2950081

A carboxylesterase containing long-chain acyl-CoA hydrolase activity was purified to apparent homogeneity from rat liver microsomes. Palmitoyl-CoA was the most preferred substrate, followed by stearoyl-CoA and oleoyl-CoA. Arachidonoyl-CoA, linoleoyl-CoA and acetyl-CoA were not hydrolysed by the enzyme. The purified enzyme had no activity on the hydrolysis of phospholipids and neutral lipids. The molecular mass of the enzyme was found to be 56 kDa by SDS/PAGE and 64 kDa by gel-filtration chromatography. On isoelectric focusing, the purified enzyme behaved like the ES-4 type, with a pI of 6.15. Determination of the amino acid sequence revealed that its N-terminal sequence is 100% homologous with the only other known N-terminal sequence for a rat carboxylesterase isoenzyme (ES-10). Enzyme activity was inhibited by lysophosphatidic acid and activated by lysophosphatidylcholine. The modulation of enzyme activity by these lysophospholipids might represent a plausible mechanism for the physiological control of acyl-CoA concentrations.