Fungal Cellulases I. General Properties of Unpurified Enzyme Preparations From Aspergillus Oryz.A'e

Abstract

The culture filtrate from A. oryzae contains enzymes capable of depolymerizing sodium carboxy-methyl cellulose (SCMC) and of splitting all beta-glucosides tested. These enzymes are produced by the mold in the absence of cellulose or any other carbon source containing beta-glucosidic linkages. The action of the enzyme degrading SCMC (the Cx enzyme of Reese, Siu and Levinson 1949) and the beta-glucosidase activities were followed iodometrically. The beta-glucosidase action was also followed colorimetrically using p-nitrophenyl-beta-glucoside as a substrate. The variation in the activity of the Cx enzyme with temp., pH, and enzyme and substrate concns., and in the presence of inhibitors, was measured and some kinetic data are also given for the beta-glucosidase activities. On the basis of these results it is concluded that the physiochemical properties of SCMC solns. make this compound an unsatisfactory substrate for kinetic studies. The true pH opt. of the Cx enzyme is about 3.5; the apparent temp. opt. is very strongly influenced by reaction time. The behavior of the Cx enzyme towards metal-complexing, oxidizing, and reducing agents can be explained if it is activated by ferric ions but the method of enzyme estimation used and the complexing properties of sodium carboxy-methyl cellulose make proof of this hypothesis difficult. The enzyme activity is also strongly affected by various organic bases, notably caffeine and quinine. The behavior of a beta-glucosidase (salicinase) towards various reagents affecting the Cx enzyme has also been tested.