Colas B, Attias J
Biochimie. 1977;59(7):577-85. doi: 10.1016/s0300-9084(77)80167-3.
Two beta-D-glycosidases have been purified from the digestive juice of Achatina balteata by acetone fractionation, ion exchange chromatography through DEAE-Sephadex A-50, ammonium sulphate fractionation and gel chromatography through Sephadex G-200. The preparations are homogeneous by p/lyacrylamide gel electrophoresis. Both enzymes are highly specific for the beta-D-anomeric configuration of the glycosidic linkage. They hydrolyse lactose, cellobiose and synthetic beta-D-galactosides, -glucosides and -fucosides at a pH optimum of 5,2 to 5,6 and are inactive on alpha-glycosides. The hydrolyzed substrates are recognized by the same catalytic site as shown by mutual competition studies between substrates and competitive inhibition observed with aldonolactones and glycopyranoses such as D-galactose, D-glucose and D-fucose. The different substrates are not hydrolyzed at the same rate by the two enzymes. They also differ by their electrophoretic mobility, their behaviour in gel chromatography and their stability towards pH and heat. The most salient property is the important beta-D-fucosidase activity of the two purified enzymes.
通过丙酮分级分离、DEAE - 葡聚糖A - 50离子交换色谱、硫酸铵分级分离以及葡聚糖G - 200凝胶色谱，从玛瑙螺消化液中纯化出了两种β - D - 糖苷酶。聚丙烯酰胺凝胶电泳显示制备物均一。两种酶对糖苷键的β - D - 异头构型具有高度特异性。它们在最适pH 5.2至5.6时可水解乳糖、纤维二糖以及合成的β - D - 半乳糖苷、β - D - 葡萄糖苷和β - D - 岩藻糖苷，而对α - 糖苷无活性。底物间相互竞争研究以及醛糖内酯和吡喃糖（如D - 半乳糖、D - 葡萄糖和D - 岩藻糖）的竞争性抑制表明，水解的底物由相同的催化位点识别。两种酶对不同底物的水解速率不同。它们在电泳迁移率、凝胶色谱行为以及对pH和热的稳定性方面也存在差异。最显著的特性是两种纯化酶具有重要的β - D - 岩藻糖苷酶活性。
