Abstract

Aspergillus versicolor grown on xylan or xylose produces two beta-xylosidases with differences in biochemical properties and degree of glycosylation. We investigated the alterations in the biochemical properties of these beta-xylosidases after deglycosylation with Endo-H or PNGase F. After deglycosylation, both enzymes migrated faster in PAGE or SDS-PAGE exhibiting the same Rf. Temperature optimum of xylan-induced and xylose-induced beta-xylosidases was 45oC and 40oC, respectively, and 35oC after deglycosylation. The xylan- induced enzyme was more active at acidic pH. After deglycosylation, both enzymes had the same pH optimum of 6.0. Thermal resistance at 55oC showed half-life of 15 min and 9 min for xylose- and xylan-induced enzymes, respectively. After deglycosylation, both enzymes exhibited half-lives of 7.5 min. Native enzymes exhibited different responses to ions, while deglycosylated enzymes exhibited identical responses. Limited proteolysis yielded similar polypeptide profiles for the deglycosylated enzymes, suggesting a common polypeptide core with differential glycosylation apparently responsible for their biochemical and biophysical differences.

• Keywords: beta-xylosidase; xylobiase; glycosylation; deglycosylation; glycoprotein; Aspergillus versicolor