The cellulase of Fusarium solani. Purification and specificity of the β-(1→4)-glucanase and the β-d-glucosidase components

Abstract

1. Cell-free culture filtrates of the fungus Fusarium solani were examined for homogeneity with respect to β-d-glucosidase and Cx activities. 2. o-Nitrophenyl β-d-glucoside and cellobiose were both used as substrates for β-d-glucosidase activity. 3. No evidence for the non-identity of nitrophenyl β-d-glucosidase and cellobiase activities could be found, either by heat treatment, gel filtration on Sephadex G-100 or by isoelectric focusing. 4. The β-d-glucosidase component was also a feeble exo-β-glucanase: it had a molecular weight of approx. 400000. 5. The fall in viscosity of a solution of CM-cellulose, the formation of reducing sugars in a solution of CM-cellulose and the solubilization of phosphoric acid-swollen cellulose (Walseth cellulose), were all used for the measurement of Cx activity. 6. The ratio of the two types of CM-cellulase activity was not changed after gel filtration on Sephadex G-100 or after chromatography on DEAE-Sephadex. 7. Three peaks of Cx activity were obtained after electrofocusing, but all three possessed the same ratio of the two types of CM-cellulase activity as well as the same CM-cellulase/Walseth activity ratio, as the unfractionated enzyme; all three isoenzymes (isoelectric points, 4.75, 4.80–4.85 and 5.15) acted in synergism with a mixture of the C1 and the β-d-glucosidase components to the same extent in the solubilization of cotton fibre. 8. The molecular weight of the Cx component was approx. 37000.