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|Title:||Purification and Properties of Three Cellobiases from Aspergillus niger A20|
|Keywords:||Purification and Properties of Three Cellobiases from Aspergillus niger A20|
|Abstract:||Three cellobiases, here called cellobiase A, B, and C, from the culture filtrate of Aspergillus niger A20, were purified by precipitation with ammo nium sulphate, gel filtration through Sephadex G-7S, and column chroma tography of DEAE-cellulose. The purified enzymes were homogeneous on polyacrylamide disk electrophoresis. The mol wt of the purified enzymes were estimated by SDS-gel electrophoresis to be 88,000, 80,000, and 71,000 for cellobiases A, B, and C, respectively. The enzymes were active at pH 4.5 and 55-60°C. The pattern of their amino acid compositions showed high contents of aspartic acid, glutamic acid, threonine, serine, and glycine. The apparent Km values for cellobiose were 0.9,1.63, and 1.0 mM for cellobiases A, B, and C, respectively. Calcium ions stimulated cellobiases Band C, and Co2+ and Mg2+ ions stimulated cellobiase A. The purified enzymes hydrolyzed cello biose and aryl-~-D-glucosides, but they had no action on sucrose, maltose, and cellulose. The three cellobiases catalyzed transglycosylase reaction, and the major product formed from cellobiose was tetramer of glucose.|
|Appears in Collections:||Chemistry|
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