Four Types of β-Xylosidases from Penicillium wortmanni IFO 7237

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Four types of β-xylosidases from a concentrated culture filtrate of Penicillium wortmanni IFO 7237, designated as xylosidase-1, -2, -3, and -4 were purified to homogeneity on SDS polyacrylamide gel electrophoresis by an alcohol precipitation, DEAE-Sephadex A-25 ion exchange chromatography, and isoelectric focusing. The molecular weights of xylosidase-1, -2, -3, and -4 were estimated to be 110, 000, 195, 000, 210, 000, and 180, 000 respectively and their isoelectric points to be 3.7, 4.28, 4.6, and 4.8. The pH optima of β-xylosidase activities were from 3 to 4.5. The optimum temperature for enzyme activities was from 55°C to 65°C. On the enzymic hydrolysis of phenyl β-Dxyloside, the reaction product of each enzyme was found to be β-D-xylose with retention of configuration. All the four β-xylosidases were free of α-xylosidase and β-glucosidase activities. All the enzyme activities of four β-xylosidases were strongly inhibited by Hg2+ and N-bromosuccinimide. With respect to the hydrolysis patterns and HPLC analysis of hydrolyzates from xylooligosaccharides, xylosidase-2 was totally different from other three as a distinct enzyme. Xylosidase-1 was also in a separate group although xylosidase-3 and -4 showed closely related action patterns as a different group.