Purification and Some Properties of a Low Endo-type Cellulase from Acremonium cellulolyticus.

Abstract

A distinct endo-Cellulase component derived from Acremonium cellulase, a commercial Cellulase material from Acremonium cellulolyticus, was extensively purified by consecutive column chromatography and was designated as cellulase I. Cellulase I was homogeneous on both Native-and SDS-PAGE, and was completely free from β-glucosidase. The enzyme showed high specific activity for Avicel and extremely low specific activity for CMC, 0.69 and 0.40 U/mg of protein, respectively. The molecular mass (SDS-PAGE) and p1 value of cellulase I were about 61 kDa and 5.0, respectively. The purified enzyme contained 19.8% carbohydrate as glucose. The N-terminal amino acid sequence from the 2nd up to the 20th residue of the enzyme wasQ-*-V-W-G-Q-*-G-G-Q-G-W-S-G-A-T-(S)-*-A-. The optimum pH and temperature for cellulase I were 5.0and 55°C, respectively. Cellulase I was completely stable over the range of pH 3.0-6.0 at 4°C for 24 h and at temperatures below 55°C. The activity of cellulase I was partially inactivated by 5 mM Mn2+, Fe2+, Hg2+ and KMn04 to various inhibition extents. Cellulase I split various cellulosic substrates to produce predominant cellobiose and a small amount of glucose as the final hydrolysis products. The enzyme was characterized as an exceedingly low endo-type cellulase on the basis of its actions on both CMC and cellooligosaccharides.