Carbohydrate metabolism in citric acid fermentation. 4. Purification and properties of aldolase from Aspergillus niger

Abstract

The aldolase of Aspergillus niger was purified by ammonium sulphate fractionation and adsorption on calcium phosphate gel. The purified aldolase was electrophoretically homogeneous. The activity per mg of the enzyme was equal to that of crystalline muscle or yeast aldolase. The properties of the enzyme and the kinetics of the reaction are described. The enzyme resembled yeast aldolase and differed from muscle aldolase in requiring heavy metals for its activity. It was inhibited by cysteine, pyrophosphate, ethylenediaminetetraacetic acid, o-phenanthroline and [alpha][alpha]''-dipyridyl. The inhibition was reversed by bivalent Zn, Mn, Fe or Co but not by Mg, Ca or Cu. A new spectrophotometric method for the estimation of aldolase activity is described. The method is based on the increase in light absorption at 240 m[mu] in the presence of hydrazine. The differences between the aldolases from different tissues are briefly discussed.