Yeast exo-β-1,3-glucanse gene (EXG1) was expressed in Escherichia coli and the recombinant enzyme (EXg1p) was characterized. The recombinant Exg1p had an apparent molecular mass of 45 kDa by SDS-PAGE and the enzyme has a broad specificity for β-1,3-link-ages as well as β-1,6-linkages, and also for other β-glucosidic linked substrates, such as cellobiose and pNPG. Kinetic analyses indicate that the enzyme prefers small substrates such as laminaribiose, gentiobiose, and pNPG rather than polysaccharide substrates, such as laminaran or pustulan. With a high concentration of laminaribiose, the enzyme catalyzed transglucosidation forming laminarioligosaccharides. The enzyme was strongly inhibited with high concentrations of laminaran.
酵母 exo-β-1,3-
葡聚糖酶
基因 (EXG1) 在大肠杆菌中表达,并对
重组酶 (EXg1p) 进行了特性分析。
重组的 Exg1p 的表观分子量为 45 kDa(通过
SDS-PAGE 测定),该酶对 β-1,3 键和 β-1,6 键具有广泛的特异性,并且对其他 β-
葡萄糖苷链接的底物(如
纤维二糖和 pN
PG)也具有活性。动力学分析表明,该酶更喜欢小底物,如兰梅糖、根茎糖和 pN
PG,而不是
多糖底物,如兰梅糖或双聚赖
氨酸。高浓度的兰梅糖时,该酶催化转
葡萄糖作用形成兰梅
寡糖。在高浓度的兰梅糖下,该酶受到强烈抑制。