Lactone-Driven Ester-to-Amide Derivatization for Sialic Acid Linkage-Specific Alkylamidation
Lactone-Driven Ester-to-Amide Derivatization for Sialic Acid Linkage-Specific Alkylamidation
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DOI：
10.1021/acs.analchem.0c02209
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发表时间：
2020-11-03
影响因子：
7.4
通讯作者：
Tanaka, Koichi
中科院分区：
文献类型：
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作者：
Furukawa, Jun-ichi;Hanamatsu, Hisatoshi;Tanaka, Koichi
唾液酸通过不同的键连接到聚糖链的非还原端，与特定的相互作用和生理事件有关。唾液酸的连锁特异性衍生化对于通过质谱法区分唾液酸非常有意义，特别是对于由唾液酸连锁类型控制的事件。在本研究中，我们证明了-2,3/8-唾液寡糖的酯化键特异性酰胺化可以通过分子内酯实现。内酯驱动的唾液酸键特异性烷基酰胺化的酯-酰胺衍生化方法，称为铅- salsa，采用溶液中酯-酰胺转化，通过与首选胺混合，直接从酯形式生成稳定的唾液酸键特异性聚糖酰胺，通过比较酯化和修饰的聚糖信号，容易分配唾液酸键。使用这种方法，我们证明了小鼠衰老过程中心肌组织中改变的n -聚糖的积累。此外，根据实验和密度泛函理论计算内酯生成反应能，我们发现内酯的稳定性对酯到酰胺的转化很重要。利用内酯形成的能量差，铅- salsa方法不仅可以用于唾液酸键特异性衍生化，而且可以用于区分与唾液酸相连的半乳糖的分支结构。这种简化和直接的唾液聚糖鉴别将有助于唾液化糖缀合物的重要研究。
Sialic acid attached to nonreducing ends of glycan chains via different linkages is associated with specific interactions and physiological events. Linkage-specific derivatization of sialic acid is of great interest for distinguishing sialic acids by mass spectrometry, specifically for events governed by sialyl linkage types. In the present study, we demonstrate that alpha-2,3/8-sialyl linkage-specific amidation of esterified sialyloligosaccharides can be achieved via an intramolecular lactone. The method of lactone-driven ester-to-amide derivatization for sialic acid linkage-specific alkylamidation, termed LEAD-SALSA, employs in-solution ester-to-amide conversion to directly generate stable and sialyl linkage-specific glycan amides from their ester form by mixing with a preferred amine, resulting in the easy assignments of sialyl linkages by comparing the signals of esterified and amidated glycan. Using this approach, we demonstrate the accumulation of altered N-glycans in cardiac muscle tissue during mouse aging. Furthermore, we find that the stability of lactone is important for ester-to-amide conversion based on experiments and density functional theory calculations of reaction energies for lactone formation. By using energy differences of lactone formation, the LEAD-SALSA method can be used not only for the sialyl linkage-specific derivatization but also for distinguishing the branching structure of galactose linked to sialic acid. This simplified and direct sialylglycan discrimination will facilitate important studies on sialylated glycoconjugates.