Streptococcus pneumoniae endohexosaminidase D; feasibility of using N-glycan oxazoline donors for synthetic glycosylation of a GlcNAc-asparagine acceptor
Streptococcus pneumoniae endohexosaminidase D; feasibility of using N-glycan oxazoline donors for synthetic glycosylation of a GlcNAc-asparagine acceptor
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DOI：
10.1039/b926078a
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发表时间：
2010-01-01
影响因子：
3.2
通讯作者：
Fairbanks, Antony J.
中科院分区：
文献类型：
--
作者：
Parsons, Thomas B.;Patel, Mitul K.;Fairbanks, Antony J.
氨基己糖苷酶 D 是来自肺炎链球菌的家族 85 糖苷水解酶，也是第一个被发现的氨基己糖苷酶，它被发现能够使用多种 N-聚糖恶唑啉供体催化带有 GlcNAc 残基的糖基氨基酸的糖基化。尽管酶催化的恶唑啉水解是一种重要的竞争反应，不能通过添加有机共溶剂或改变反应 pH 来抵消，但通过顺序添加多当量的恶唑啉供体可以实现高产合成过程，证明了该酶作为合成特定糖复合物的生物催化剂的合成潜力。值得注意的是，Endo-D 在所用条件下似乎不会水解所得产物。 Endo D 表现出的合成活性意味着其他尚未测试的 GH85 家族酶可能表现出类似的合成潜力。此外，由于 Endo D 能够裂解附着在单克隆抗体 (mAb) 上的 N-聚糖，并且还能够裂解核心岩藻糖基化的聚糖，因此，只要能够克服直接恶唑啉水解的限制，将 Endo D 开发为合成重要的确定均质复合糖缀合物的有用生物催化剂可能具有巨大的未来潜力。
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.