Heterogeneity and Developmental Alteration of Esterase Isoenzymes in Conidial Germination of Neurospora crassa

Abstract

Summary: At least 11 esterase isoenzymes have been resolved from conidia of six strains of Neurospora crassa on starch gel zymograms using β-naphthyl acetate as substrate. By means of inhibitor studies, three of them were determined to be acetylesterases and nine to be carboxylesterases. Carboxylesterases could be distinguished from acetylesterases by their positive reaction with α-naphthyl butyrate. The distribution of these multiple forms of esterases in conidia was clearly strain specific. Each strain contained two forms of acetylesterase and from zero to three forms of carboxylesterase. These esterases could not hydrolyse the naphthyl esters of aliphatic carboxylic acids larger than butyrate or that of benzoate. During the first 20 h of conidial germination, a marked decrease in esterolytic activity was observed for most of the carboxylesterases but not for the acetylesterases. This might indicate that digestion of aliphatic esters is involved in the initial stage of conidial germination.