[Purification of exo-1,4-beta-xylosidase from Aspergillus niger 15]

From the preparation of xylanase of the fungus Aspergillus niger 15 exo-1,4-beta-xylosidase was isolated by means of ethanol fractionation and chromatography on columns of Sephadex G-50, cellulose DE-52, Sephadex SP C-50, Sephadex G-200. The isolated enzyme (with the purification degree as calculated per protein 199, and yield with respect to activity 42.5%) was homogeneous during gel filtration, polyacrylamide gel electrophoresis in the presence and absence of Na dodecyl sulfate, ultracentrifugation and isoelectric focusing. Exo-1,4-beta-xylosidase had a molecular mass of 253,000 as shown by gel filtration and 122,000 as shown by Na dodecyl sulfate polyacrylamide gel electrophoresis; its sedimentation coefficient was 10.6 S and isoelectric point was pI 4.9. The specific activity of the homogeneous enzyme was 35.2 u./mg protein with respect to p-nitrophenyl-beta-D-xylopyranoside and 30.2 u./mg protein with respect to xylobiose.