PURIFICATION AND CHARACTERIZATION OF EXTRACELLULAR AND CELL-WALL BOUND BETA-GLUCOSIDASES FROM ASPERGILLUS-KAWACHII

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