Centre de Recherches sur les Macromolécules Végétales (CERMAV-CNRS), Affiliated with Grenoble University and the Institut de Chimie Moléculaire de Grenoble, Domaine Universitaire de Grenoble, 601 rue de la Chimie, B. P. 53, 38041 Grenoble cedex 9 (France).
Chembiochem. 2014 Jan 24;15(2):293-300. doi: 10.1002/cbic.201300597. Epub 2013 Dec 20.
We report the enzymatic synthesis of α-D-glucopyranosyl-(1→4)-α-L-rhamnopyranoside and α-D-glucopyranosyl-(1→3)-α-L-rhamnopyranoside by using a wild-type transglucosidase in combination with glucoamylase and glucose oxidase. It was shown that Bacillus circulans 251 cyclodextrin glucanotransferase (CGTase, EC 2.1.4.19) can efficiently couple an α-L-rhamnosyl acceptor to a maltodextrin molecule with an α-(1→4) linkage, albeit in mixture with the α-(1→3) regioisomer, thus giving two glucosylated acceptors in a single reaction. Optimisation of the CGTase coupling reaction with β-cyclodextrin as the donor substrate and methyl or allyl α-L-rhamnopyranoside as acceptors resulted in good conversion yields (42-70%) with adjustable glycosylation regioselectivity. Moreover, the efficient chemical conversion of the products of CGTase-mediated cis-glucosylation into protected building blocks (previously used in the synthesis of O-antigen fragments of several Shigella flexneri serotypes) was substantiated. These novel chemoenzymatic strategies towards useful, convenient intermediates in the synthesis of S. flexneri serotypes 2a and 3a oligosaccharides might find applications in developments towards synthetic carbohydrate-based vaccine candidates against bacillary dysentery.
我们报告了使用野生型转葡糖基酶与糖化酶和葡萄糖氧化酶联合合成α-D-吡喃葡萄糖基-(1→4)-α-L-鼠李吡喃糖苷和α-D-吡喃葡萄糖基-(1→3)-α-L-鼠李吡喃糖苷。结果表明，环状糊精葡萄糖基转移酶（CGTase，EC 2.1.4.19）可以有效地将α-L-鼠李糖受体与具有α-(1→4)键的麦芽糊精分子偶联，尽管与α-(1→3)区域异构体混合，从而在单个反应中得到两种葡萄糖化受体。用β-环糊精作为供体底物和甲基或烯丙基α-L-鼠李吡喃糖苷作为受体对 CGTase 偶联反应进行优化，得到了良好的转化率（42-70%），并且糖苷化区域选择性可调。此外，还证实了 CGTase 介导的顺式葡糖基化产物转化为保护基构建块的有效化学转化（先前用于合成几种福氏志贺菌血清型的 O-抗原片段）。这些针对有用的新型化学酶策略，方便的中间体合成志贺菌血清型 2a 和 3a 寡糖可能会在针对细菌性痢疾的合成基于碳水化合物的疫苗候选物的开发中得到应用。
