2000 Volume 47 Issue 3-4 Pages 293-302
Two distinct endo-cellulase components derived from Acremonium cellulase, a commercial cellulase preparation from Acremonium cellulolyticus, were extensively purified by consecutive column chromatography and designated as cellulase III-A and cellulase III-B. Cellulases III-A and III-B were each homogeneous on both Native- and SDS-PAGE, and were completely free from β-glucosidase. The molecular mass (SDS-PAGE) and pI Tvalues of cellulases IIIV-A and III-B were 58 kDa and 4.6, and 49 kDa and 4.2, respectively. Both enzymes contained 14-16% carbohydrates (as glucose). The N-terminal amino acid sequences from the 2nd up to the 20th residue of bothenzymes were determined by Edman degradation. Some enzymatic properties of the purified cellulases were investigated. The optimum pH and temperature for cellulases III-A and III-B were pH 5.5 and 55°C, and pH 5.5 and 65°C, respectively. Cellulases III-A and III-B were completely stable over the range of pH 4.2-8.0 at 4°C for 24 h and at temperatures below 55°C, and pH 3.3-7.8 and below 60°C, respectively. Cellulases III-A and III-B retained 25 and 88% of the original CMC-saccharification activities, respectively, after heating at 70°C for 10 min. The hydrolysis of CMC by cellulase III-B was more endo-lytic than that by cellulase III-A. Both enzymes splitvarious soluble and insoluble substrates to produce predominant cellobiose and a small amount of glucose as the final hydrolysis products.