Purification and characterization of β-xylosidase from Aureobasidium pullulans
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- Dobberstein, J. & Emeis, C.C. Appl Microbiol Biotechnol (1991) 35: 210. doi:10.1007/BF00184688
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β-Xylosidase was obtained from Aureobasidium pullulans CBS 58475 with an activity of 0.35 units/ml culture filtrate. The production of the enzyme was strongly inducible. β-Xylosidase was purified in two steps by anion exchange and gel-permeation chromatography to high purity. The enzyme is a glycoprotein with an apparent molecular mass of 224 kDa in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and separates into two subunits of equal molecular mass. After SDS-PAGE β-xylosidase could be renatured and stained with methylumbelliferyl-β-xylopyranoside. The enzyme was able to split substrates of other glycosidases. The maximum activity was reached at pH 4.5 and 80° C. β-Xylosidase showed high stability over a broad pH range from pH 2.0 to 9.5 and up to 70° C. Analysis of cleavage patterns revealed that the enzyme was a typical glycosidase. Larger oligosaccharides consisting of xylose were degraded by an exomechanism together with a transxylosylation reaction.