[解纤维素真菌白地霉3c的β-葡萄糖苷酶特性]

[Properties of beta-glucosidase from the cellulolytic fungus Geotrichum candidum 3c].

作者信息

Rumiantseva G N, Rodionova N A

出版信息

Biokhimiia. 1982 Jan;47(1):108-14.

Abstract

beta-Glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) splitting p-nitrophenyl-beta-D-glucosidase was isolated from cellular preparation of the fungus Geotrichum candidum 3c "cellocandine G10x" and purified 38-fold. The enzyme was homogeneous during ultracentrifugation, gel-filtration, isoelectrofocusing and disc-electrophoresis in polyacrylamide gel and had a pI of 4.2, sedimentation coefficient of 2.6S and molecular weight of 120 000. The enzyme had maximal activity at pH 5.6, 45 degrees and retained up to 45% of its activity under optimal conditions (pH, t degrees) after 48 hr incubation. beta-Glucosidase did not split disaccharides, e. g. lactose cellobiose, laminaribiose, gentibiose as well as o-nitrophenyl-beta-D-galactoside, methyl-beta-D-xyloside. The enzyme hydrolyzed p-nitrophenyl-beta-D-glucopyranoside (Km = 0.18 mM) and some plant beta-glucosides, such as phenylethyl-beta-D-glucopyranoside from rose petals and diosgenine tetrasaccharide from deltoid dioscorea (Km = 0.26 mM).

摘要

从白地霉3c“纤维二糖酶G10x”的细胞制剂中分离出可分解对硝基苯基-β-D-葡萄糖苷的β-葡萄糖苷酶（β-D-葡糖苷葡糖水解酶，EC 3.2.1.21），并将其纯化了38倍。该酶在超速离心、凝胶过滤、等电聚焦以及聚丙烯酰胺凝胶圆盘电泳过程中均表现为均一性，其等电点为4.2，沉降系数为2.6S，分子量为120000。该酶在pH 5.6、45℃时具有最大活性，在最佳条件（pH、温度）下孵育48小时后仍保留其活性的45%。β-葡萄糖苷酶不能分解二糖，如乳糖、纤维二糖、昆布二糖、龙胆二糖以及邻硝基苯基-β-D-半乳糖苷、甲基-β-D-木糖苷。该酶能水解对硝基苯基-β-D-吡喃葡萄糖苷（Km = 0.18 mM）以及一些植物β-葡萄糖苷，如玫瑰花瓣中的苯乙基-β-D-吡喃葡萄糖苷和三角叶薯蓣中的薯蓣皂苷元四糖（Km = 0.26 mM）。