A method was developed to distinguish both the linkage position and the anomericity of all reducing and two nonreducing glucopyransosyl–glucose disaccharides using only electrospray ionization–mass spectrometry/mass spectrometry (ESI–MS/MS). Carbohydrates are well-known to form complexes with metal cations during electrospray ionization. Addition of a lithium salt to a solution containing a disaccharide, M, results in [M + Li]⁺ after ESI. Collision-induced dissociation of these ions creates product ions at m/z 187 and m/z 169 from cleavage of the glycosidic bond and are present for all disaccharides studied. Both of these product ions were found to adduct water after their formation in a quadrupole ion trap. The kinetics of this water adduction can be measured by isolating either of the product ions and waiting a short time (<1 s) before mass analysis. Additionally, for both product ions, only a fraction of the ions were able to adduct water. This unreactive fraction was measured along with the reaction rate, and the combination of these two values was found to be unique for each disaccharide. Additionally, after CID, a 1000 ms delay can be added, and the ratios of the resulting products ions of m/z 169, 187, and 205 can be used to distinguish linkage position and anomericity with a single tandem mass spectrometry experiment.

中文翻译：

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通过水与锂化分子的区别来区分葡萄糖-葡萄糖二糖的键合位置和端基构型

开发了一种仅使用电喷雾电离质谱/质谱（ESI-MS / MS）来区分所有还原性和两种非还原性吡喃葡萄糖基-葡萄糖二糖的键合位置和异头异构体的方法。众所周知，碳水化合物在电喷雾电离过程中会与金属阳离子形成络合物。将锂盐添加到含有二糖M的溶液中，得到ESI后的[M + Li] ⁺。这些离子的碰撞诱导解离在m / z 187和m / z处产生产物离子169是从糖苷键的裂解而来的，并且存在于所有研究的二糖中。发现这两种产物离子在四极离子阱中形成后都会加水。可以通过分离任何一种产物离子并在质量分析之前等待一小段时间（<1 s）来测量这种水加合物的动力学。另外，对于两种产物离子，仅一小部分离子能够加水。测量该反应性分数和反应速率，发现这两个值的组合对于每种二糖而言是唯一的。另外，在CID之后，可以添加1000 ms的延迟，并且生成的产物离子的比率为m / z 169、187和205可用于通过单个串联质谱实验区分键的位置和异头作用。