Purification and Characterization of Extracellular and Cell Wall Bound β-Glucosidases from Aspergillus kawachii

Abstract

We isolated two extracellular β-glucosidases (EX-1: 145 kDa, EX-2: 130 kDa) and one cell wall bound β-glucosidase (CB-1: 120 kDa) from Aspergillus kawachii and characterized their physical and kinetic properties. From the results of N-terminal amino acid sequence, enzymatic parameters and deglycosylation of the three purified enzymes, we strongly suggest that these three enzymes were products of the same gene, modified by different degree of glycosylation. All three purified β-glucosidases adsorbed to the purified cell wall fraction of this strain. This association could dramatically improve the stability of purified enzymes. These three purified β-glucosidases were readily inactivated even in moderate conditions but became very stable upon the addition of the purified cell wall fraction. The all purified β-glucosidases were stable in the range of pH 2.0-9.0 and stable below 30°C with 2 mg/ml of the purified cell wall fraction.

• Aspergillus
• β-glucosidase
• purification
• sugar chain
• cell wall