Cellulase from Fusarium solani: purification and properties of the C1 component

The C1 component from Fusarium solani cellulase was purified extensively by molecular-sieve chromatography on Ultrogel AcA-54 and ion-exchange chromatography on DEAE-Sephadex. The purified component showed little capacity for hydrolysing highly ordered substrates (e.g., cotton fibre), but poorly ordered substrates (e.g., H3PO4-swollen cellulose), and the soluble cello-oligosaccharides cellotetraose and cellohexaose, were readily hydrolysed; cellobiose was the principal product in each case. Attack on O(-carboxymethyl)cellulose, a substrate widely used for measuring the activity of the randomly acting enzymes (Cx enzymes) of the cellulase complex, was minimal, and ceased after the removal of a few unsubstituted residues from the end of the chain. These observations, and the fact that the rate of change of degree of polymerisation of H3PO4-swollen cellulose was very slow compared with that effected by the randomly acting endoglucanases (Cx, CM-cellulases), indicate that C1 is a cellobiohydrolase. Fractionation by a variety of methods gave no evidence for the non-identity of the cellobiohydrolase and the component that acted in synergism with the randomly acting Cx enzyme when solubilizing cotton fibre.