Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, UKOX1 3TA.
Org Biomol Chem. 2010 Apr 21;8(8):1861-9. doi: 10.1039/b926078a.
Endohexosaminidase D, a family 85 glycoside hydrolase from S. pneumoniae and the first endohexosaminidase to be discovered, is found to be capable of catalysing the glycosylation of a glycosyl amino acid bearing a GlcNAc residue using a variety of N-glycan oxazoline donors. Although enzyme-catalysed oxazoline hydrolysis is a significant competing reaction that is not countered by the addition of organic co-solvents or variation of reaction pH, a high yielding synthetic process can be achieved by the sequential addition of multiple equivalents of oxazoline donor, demonstrating the synthetic potential of this enzyme as a biocatalyst for the synthesis of defined glycoconjugates. Notably Endo-D does not appear to hydrolyse the resulting products under the conditions used. The synthetic activity displayed by Endo D implies that other, as yet untested, family GH85 enzymes may display similar synthetic potential. Furthermore since Endo D is capable of cleaving N-glycans attached to monoclonal antibodies (mAbs), and also of cleaving glycans that are core-fucosylated, the development of Endo D as a useful biocatalyst for the synthesis of important defined homogeneous complex glycoconjugates may have significant future potential, provided that the limitation of direct oxazoline hydrolysis can be surmounted.
来自肺炎链球菌的家族 85 糖苷水解酶内己糖胺酶 D 是第一种被发现的内己糖胺酶，能够使用各种 N-糖基噁唑啉供体催化糖基氨基酸的糖基化。尽管酶催化的噁唑啉水解是一个重要的竞争反应，不能通过添加有机溶剂或改变反应 pH 值来抵消，但通过连续添加多个当量的噁唑啉供体，可以实现高产率的合成过程，这表明该酶作为合成定义糖缀合物的生物催化剂具有潜在的合成能力。值得注意的是，内-D 在使用的条件下似乎不会水解生成的产物。内-D 显示的合成活性表明，其他尚未测试的家族 GH85 酶可能具有类似的合成潜力。此外，由于内-D 能够切割连接到单克隆抗体 (mAb) 的 N-聚糖，也能够切割核心岩藻糖基化的聚糖，因此，内-D 作为合成重要的定义均相复杂糖缀合物的有用生物催化剂的发展可能具有重要的未来潜力，前提是可以克服直接噁唑啉水解的限制。
