Purification and properties of a phenol carboxylic acid acyl esterase from Aspergillus flavus

Aspergillus flavus produces an extracellular esterase that hydrolyses phenolic carboxylic acid acyl esters. An assay based upon the measurement of the rate of release of phloroglucinol on hydrolysis of the ester of phloroglucinol and protocatechuic acid is described. The most active preparation hydrolyzed 30.8 μmoles of substrate per minute per milligram of protein and was active against a wide range of esters of meta and para hydroxybenzoic acid derivatives.The enzyme was isolated as a homogeneous protein, as judged by ultracentrifugation and by electrophoresis and had an isoelectric point of pH 4.45. The molecular weight was determined as 166 000. The enzyme is a glycoprotein containing 42.8% carbohydrate and the amino acid composition is described.