Murata T, Itoh T, Hayakawa Y, Usui T
Faculty of Agriculture, Department of Applied Biological Chemistry, Shizuoka University.
J Biochem. 1996 Oct;120(4):851-5. doi: 10.1093/oxfordjournals.jbchem.a021490.
beta-Galactosidase from porcine testes induced regioselective transglycosylation from lactose to the 3-position of 2-acetamido glycosides. When alpha-D-GalNAc-OC6H4NO2-p was used as an acceptor, the enzyme synthesized mainly beta-D-Gal-(1-->3)-alpha-D-GalNAc-OC6H4NO2-p with its (1-->6) linked isomer. The use of an inclusion complex of the glycoside acceptor with beta-CD increased the efficiency of transglycosylation by increasing the solubility of the acceptor. In the same way, the use of beta-D-GalNAc-OC6H4NO2-p as acceptor led to the preferential synthesis of beta-D-Gal-(1-->3)-beta-D-GalNAc-OC6H4NO2-p over that of its (1-->6) linked isomer. beta-D-Gal-(1.3)-beta-D-GlcNAc-OC6H4NO2-p was also synthesized with beta-D-GlcNAc-OC6H4NO2-p acceptor by the consecutive use of beta-D-galactosidases from porcine testes and Bacillus circulans. These enzyme reactions are efficient enough to allow the one-pot preparation of the desired disaccharide glycosides.
猪睾丸β-半乳糖苷酶可诱导乳糖向2-乙酰氨基糖苷3位的区域选择性转糖基化反应。以α-D-氨基半乳糖-邻硝基苯基糖苷为受体时，该酶主要合成β-D-半乳糖-(1→3)-α-D-氨基半乳糖-邻硝基苯基糖苷及其(1→6)连接的异构体。糖苷受体与β-环糊精形成的包合物通过提高受体的溶解度，增加了转糖基化反应的效率。同样，以β-D-氨基半乳糖-邻硝基苯基糖苷为受体时，优先合成的是β-D-半乳糖-(1→3)-β-D-氨基半乳糖-邻硝基苯基糖苷，而非其(1→6)连接的异构体。通过连续使用猪睾丸β-半乳糖苷酶和环状芽孢杆菌β-半乳糖苷酶，还可利用β-D-氨基葡萄糖-邻硝基苯基糖苷受体合成β-D-半乳糖-(1,3)-β-D-氨基葡萄糖-邻硝基苯基糖苷。这些酶促反应效率很高，足以实现所需二糖糖苷的一锅法制备。
