Partial characterization of β- d-xylosidase from wheat malts

Abstract

Arabinoxylans (AXs) from wheat malts potentially affect beer quality and production. β- d-Xylosidase is a key enzyme that degrades the main chains of AXs to produce xylose. This study performed a partial characterization of β- d-xylosidase from wheat malts. The optimal temperature was 70°C and the enzyme exhibited excellent thermostability, that is, residual activities were 92.6% at 60°C for 1h. The enzyme was stable over a pH range of 3.0-6.0 and showed optimum activity at pH3.5 and 4.5. Kinetic parameters Km and Vmax of wheat malt β- d-xylosidase against p-nitrophenyl-xyloside were 1.74mmolL-1 and 0.76m mmin-1, respectively. The enzyme activity was severely inhibited by Cu2+, moderately inhibited by Mn2+, Mg2+, Al3+, Ca2+, Ba2+ and Na+ and mildly inhibited by Fe3+ and Fe2+. The partial enzymatic characterization achieved in this study can be used as a theoretical basis for purifying β- d-xylosidase from wheat malts.