The mechanism of enzymatic cellulose degradation .1. Purification and some properties of cellulolytic enzymes from Aspergillus niger UC

Cellulases from a mutant (cellulase higher producer) obtained by UV treatment, Aspergillus niger UC were fractionated into Avicel hydrolyzing cellulase (Avicelase), carboxymethyl-cellulase (CMCase) and beta-glucosidase by DEAE-Sepharose CL-6B column chromatography. Avicelase and CMCase were further purified by a multistep procedure involving Amberlite CG-50 and Sephadex G-100. Purification of beta-glucosidase was carried out in three steps: by Sephadex G-100 followed by Amberlite CG-50 and Concanavalin A-Sepharose. All purified enzymes were homogeneous as judged by SDS polyacrylamide slab gel electrophoresis. The activities of both Avicelase and CMCase were optimum at pH 4.5 and 40- 50 degrees C. Avicelase was stable in the pH range 5.0 to 6.5 at temperatures below 50 degrees C, while CMCase was stable in the pH range 4.0 to 7.0 at temperatures below 60 degrees C. The molecular weights of Avicelase, CMCase and beta-glucosidase were estimated to be 80,000, 32,000 and 120,000, respectively. A strong synergistic action was shown by the combination of Avicelase along with CMCase and beta-glucosidase.