β-d-Gal-(1→4)-β-d-Glc-OC6H4NO2-p and its isomers (β-d-Gal-(l→3)-β-d-GIc-OC6H4NO2-p and β-d-Gal-(1→6)-β-d-Glc-OC6H4NO2-p) were synthesized from lactose and β-d-Glc-OC6H4NO2-p, using transglycosylation by the β-d-galactosidase from Bacillus circulans. This reaction was efficient enough for us to do a one-pot preparation of galactosyl-glucoside from lactose. The order of the production of the transfer products was (1→4) ≫ (1→3) > (1→6) in the initial stage of the reaction, and the same relationship was observed for the hydrolytic rate toward the three galactosyl-glucosides. The production of (1→4)- and (1→3)-linkages greatly decreased during the subsequent reaction and much more of the (1→6)- than of the (1→4)- and (1→3)-transfer products was found in the later stage of the reaction.
以
乳糖和β-d-Glc-OC6H4NO2-p为原料,利用环状芽孢杆菌的β-d-半
乳糖苷酶进行转糖基化,合成了β-d-Gal-(1→4)-β-d-Glc-OC6H4NO2-p及其异构体(β-d-Gal-(l→3)-β-d-GIc-OC6H4NO2-p和β-d-Gal-(1→6)-β-d-Glc-OC6H4NO2-p)、利用环状芽孢杆菌中的β-d-半
乳糖苷酶进行转糖基化。这一反应的效率足以让我们从
乳糖中一次性制备半
乳糖苷-
葡萄糖苷。在反应初始阶段,转移产物的生成顺序为(1→4)≫(1→3)>(1→6),三种半
乳糖苷的
水解速率也有相同的关系。在随后的反应中,(1→4)-和(1→3)-连接的产生量大大减少,在反应的后期阶段,发现(1→6)-转移产物比(1→4)-和(1→3)-转移产物多得多。