PURIFICATION AND CHARACTERIZATION OF HUMAN HEART FATTY-ACID ETHYL-ESTER SYNTHASE CARBOXYLESTERASE/

Fatty acid ethyl ester synthase metabolizes ethanol npn-oxidatively in those extrahepatic organs most commonly damaged by alcohol abuse. Thi s study was designed to purify human myocardial fatty acid ethyl ester synthase (FAEES)/carboxylesterase from human heart, The enzyme was pu rified to homogeneity after chromatography over DEAF-cellulose, Sephad ex G-100 and hydroxylapatite. The homogenous enzyme, 62 kDa, has both synthase and carboxylesterase activities. The N-terminal amino acid se quence of the first 17 residues of the purified enzymes were 88% homol ogous to that of the carboxylesterase from rat liver and adipose tissu e. Antibody was raised against pure synthase/carboxylesterase, cross-r eacted with human cytosolic and microsomal fractions. With a constant oleic acid concentration of 0.25 mM, a calculated apparent K-m and V-m ax for ethanol were 0.30 M and 3700 nmol/mg protein/h., respectively, With constant ethanol concentrations of 1.2 M, the activity increased with the concentration of oleic acid to 0.17 mM, plateau to 0.25 mM. B ecause synthase/carboxylesterase esterifies free fatty acids with etha nol to produce its esters with potentially toxic effects, it may now b e feasible to establish a link between alcohol consumption and end-org an damage. (C) 1996 Academic Press Limited