Purification and some properties of .BETA.-xylosidase from Emericella nidulans.

Abstract

β-Xylosidase was purified 662 fold from a culture filtrate by ammonium sulfate fractionation, gel filtration on Biogel P-100, DEAE-Sephadex chromatography, and gel filtration on Sephadex G-200. With isoelectric focusing, the purified β-xylosidase found to be homogeneous on SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis. The molecular weight was estimated by gel filtration to be 240,000, and 116,000 by SDS polyacrylamide gel electrophoresis. The purified β-xylosidase had an isoelectric point at pH 3.25, and contained 4% carbohydrate residue. The optimum pH was found to be in the range of 4.5 ~ 5, and the optimum temperature was 55°C. The enzyme activity was inhibited by Hg2 +, SDS, and N-bromosuccinimide at a concentration of 1 × 10−3 m, and also p-chloromercuribenzoate at a concentration of 1 × 10−4m. The purified enzyme hydrolyzed phenyl β-d-xyloside (ko = 302.6 sec−1),β-nitrophenyl β-d-xyloside (ko = 438.9 sec−1), o-nitrophenyl β-d-xyloside (ko = 431.0 sec−1), p-chlorophenyl β-d-xylosid...