Purification and characterization of an endocellulase from the thermophilic fungus Chaetomium thermophilum CT2

• Published in: Enzyme and microbial technology Vol. 33; no. 7; pp. 932 - 937
• Main Authors: Li, Duo-Chuan, Lu, Mei, Li, Ya-Ling, Lu, Jing
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.12.2003; Elsevier Science
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; carbohydrates; Chaetomium thermophilum; Characterization; Endocellulase; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydrolases; phosphoric acid; Purification; sodium salts; Characterization; Purification; Endocellulase; Chaetomium thermophilum; Thermoproteales; Archaeobacteria; Enzyme; Fungi; Chaetomium thermophile; Cellulase; Thermophilum; Glycosidases; Chaetomium; Bacteria; Hydrolases; Thermoproteaceae; Ascomycetes; O-Glycosidases; Thallophyta
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/S0141-0229(03)00245-X

Chaetomium thermophilum CT2 produced endocellulases at 50 °C, when grown on 2% microcrystalline cellulose, 1% soluble starch, and 0.4% yeast extract medium. A major endocellulase component was purified to homogeneity by fractional ammonium sulphate precipitation, ion-exchange chromatography on DEAE-Sepharose, Phenyl-Sepharose hydrophobic interaction chromatography and gel filtration on Sephacryl S-100. The molecular weight of the enzyme was estimated to be 67.8 kDa and the enzyme was found to be a glycoprotein containing 18.9% carbohydrate. The K m of the purified enzyme for carboxymethyl cellulose, sodium salt (CMC), was 4.6 mg ml −1. The enzyme displayed highest activity towards CMC and significantly lower activities towards phosphoric acid swollen cellulose and filter paper. The activity was enhanced in the presence of Na +, K + and Ca 2+ but inhibited by Hg 2+, Zn 2+, Ag +, Mn 2+, Ba 2+, Fe 2+, Cu 2+, Mg 2+ and NH 4 +. Optimum activity was at 60 °C and pH 4.0. The enzyme was stable over 60 min incubation at 60 °C and half-life at 70, 80 and 90 °C was approximately 45, 24 and 7 min, respectively.