Purification and characterization of an intracellular alpha-D-xylosidase from Penicillium wortmannii IFO 7237.

Intracellular alpha-D-xylosidase from Penicillium wortmannii IFO 7237 was obtained by grinding the mold with almina in phosphate buffer, and the cell-free extract was purified to a homogeneous state on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight was estimated to be 290,000 by gel filtration chromatography (Superdex 200) and 73,000 was obtained by SDS-PAGE. The purified alpha-D-xylosidase had an isoelectric point at pH 5.0. The optimum activity for the enzyme was found to be at pH 6.5 and 45 degrees C. The enzyme showed a hydrolytic activity on p-NO2-phenyl-alpha-D-xylopyranoside (alpha-p-NPX) while methyl-alpha-D-xylopyranoside (alpha-MX) was not hydrolyzed at all. It also showed lower activity for xyloglucan oligosaccharides. The apparent Km values of the enzyme for alpha-p-NPX and isoprimeverose were 1.9 mM and 50 mM, respectively.