Purification and some properties of carboxylesterase of rat adipose tissue

Carboxyl ester hydrolase was obtained from rat epididymal adipose tissue in an electrophoretically homogeneous form. Purification was achieved by acetone precipitation, followed by successive chromatographies on DEAE-cellulose and hydroxyapatite and then isoelectric focusing. The monomeric molecular weight of the enzyme was 65,000 and the enzyme associated to form trimers. The enzyme had an isoelectric point at pH 5.9 and contained 2.1% carbohydrate moiety per protein with a molecular weight of 65,000. The amino terminal residue of the enzyme was glycine. The enzyme catalyzed the hydrolysis of short chain triacylglycerols such as tributyrin and medium chain monoacylglycerols such as monocaprin, but not the hydrolysis of cholesterol ester. The optimum pH for the enzymatic function of this enzyme for methyl butylate was 8.0. An antibody against the highly purified enzyme preparation induced in rabbits strongly inhibited the esterase of rat adipose tissue, but did not inhibit the esterase of rat liver, intestinal mucosa and serum.