The pectic enzymes of Aspergillus niger. 2. Endopolygalacturonase

Abstract

Endo-polygalacturonase has been separated from the culture fluid of Aspergillus niger with a purification factor of 400-fold and a recovery of 34%. The preparation obtained was homogeneous on paper electrophoresis at pH 7-2 and pH 8-0, and of moderate stability with an optimum for stability of about pH 6. The enzyme rapidly lowered the viscosity of a solution of pectic acid and released reducing groups from it according to a random pattern of hydrolysis, but the digestion was not complete. Pectin underwent only a very slight degradation, sufficient to show a fall in viscosity but with little release of reducing groups. Tetragalact-uronic acid was rapidly split to tri- and mono-galacturonic acid, and trigalacturonic acid was slowly split to di- and mono-galacturonic acid, but the digalacturonic acid was not attacked.