Purification and Characterization of an β-D-Xylosidase from Candida utilis IFO 0639

An intracellular β-D-xylosidase from Candida utilis IFO 0639 was purified to homogeneity through four chromatographic steps. The molecular mass of the enzyme was estimated to be 92 kDa by SDS-PAGE. The enzyme had an isoelectric point at 5.6,and was most active at pH 6.0 and at around 40℃. Ethanol at an optimal concentration (10%, v/v) stimulated the initial enzyme activity by 57%. D-Xylose, the product of the β-D-xylosidase, has no effect on the enzyme activity at 300 mM. The β-D-xylosidase was highly specific to the β-D-xylopyranoside configuration. The enzyme hydrolyzed β-1,4-linked xylo-oligosaccharides with chain lengths from 2 to 5 by releasing xylose from the nonreducing end. It showed no activity against xylan. The enzyme efficiently released monoterpenols from an aroma precursor extracted from Muscat grape juice. The fermentation of Muscat juice coupled with the enzyme addition produced a small increase in the concentration of monoterpenols.