Department of Microbiology and Audubon Sugar Institute, Louisiana State University, Baton Rouge, Louisiana 70803.
Appl Environ Microbiol. 1982 Dec;44(6):1289-95. doi: 10.1128/aem.44.6.1289-1295.1982.
A beta-glucosidase (EC 3.2.1.21) from the fungus Aspergillus terreus was purified to homogeneity as indicated by disc acrylamide gel electrophoresis. Optimal activity was observed at pH 4.8 and 50 degrees C. The beta-glucosidase had K(m) values of 0.78 and 0.40 mM for p-nitrophenyl-beta-d-glucopyranoside and cellobiose, respectively. Glucose was a competitive inhibitor, with a K(i) of 3.5 mM when p-nitrophenyl-beta-d-glucopyranoside was used as the substrate. The specific activity of the enzyme was found to be 210 IU and 215 U per mg of protein on p-nitrophenyl-beta-d-glucopyranoside and cellobiose substrates, respectively. Cations, proteases, and enzyme inhibitors had little or no effect on the enzyme activity. The beta-glucosidase was found to be a glycoprotein containing 65% carbohydrate by weight. It had a Stokes radius of 5.9 nm and an approximate molecular weight of 275,000. The affinity and specific activity that the isolated beta-glucosidase exhibited for cellobiose compared favorably with the values obtained for beta-glucosidases from other organisms being studied for use in industrial cellulose saccharification.
真菌曲霉菌中提取的β-葡萄糖苷酶（EC 3.2.1.21）经圆盘丙烯酰胺凝胶电泳显示已高度纯化为均一性。最佳活性在 pH 4.8 和 50°C 下观察到。β-葡萄糖苷酶对 p-硝基苯基-β-d-吡喃葡萄糖苷和纤维二糖的 K(m)值分别为 0.78 和 0.40 mM。葡萄糖是竞争性抑制剂，当使用 p-硝基苯基-β-d-吡喃葡萄糖苷作为底物时，K(i)为 3.5 mM。该酶的比活性在 p-硝基苯基-β-d-吡喃葡萄糖苷和纤维二糖底物上分别为 210 IU 和 215 U/毫克蛋白。阳离子、蛋白酶和酶抑制剂对酶活性几乎没有影响。β-葡萄糖苷酶被发现是一种糖蛋白，其碳水化合物含量占重量的 65%。它的斯托克斯半径为 5.9nm，近似分子量为 275,000。分离的β-葡萄糖苷酶对纤维二糖的亲和力和比活性与正在研究用于工业纤维素糖化的其他生物体中的β-葡萄糖苷酶的值相当。
