Ren Rongfan, Yuan Minghui, Li Hongli, Chen David Da Yong
Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
Anal Chem. 2023 Jan 31;95(4):2213-2220. doi: 10.1021/acs.analchem.2c03485. Epub 2023 Jan 12.
Carbohydrates play critically important roles in energy supply and biological functions in living systems. However, it has been a great challenge to identify saccharides and distinguish their isomers because they have highly similar structures and many possible positions for glycosidic linkages. In this work, an ambient ionization tandem mass spectrometry method was developed to characterize disaccharide structural isomers with in situ methylation. The direct analysis in real time ion source can be used to facilitate the methylation reaction of disaccharides with tetramethylammonium hydroxide. The hydroxyl groups of disaccharides can be methylated instantaneously, and the products can be ionized at the same time. The methylated product ions from full scan mass spectrometry (MS) and tandem MS can be used to distinguish a variety of disaccharide structural isomers with different glycosidic linkages, compositions, and configurations. Characteristic marker ions were discovered, and they can be used for the assignment of linkage type and identification of specific isomeric forms. The method was used for the direct identification of disaccharide isomers from real commercial products such as honey, wine, and milk without complex sample pretreatment or chromatographic separation.
碳水化合物在生命系统的能量供应和生物学功能中发挥着至关重要的作用。然而，由于糖类结构高度相似且糖苷键存在许多可能的连接位置，因此识别糖类并区分其异构体一直是一项巨大的挑战。在这项工作中，开发了一种常压电离串联质谱方法，通过原位甲基化来表征二糖结构异构体。实时直接分析离子源可用于促进二糖与氢氧化四甲铵的甲基化反应。二糖的羟基可瞬间甲基化，产物可同时被电离。全扫描质谱（MS）和串联质谱得到的甲基化产物离子可用于区分具有不同糖苷键、组成和构型的多种二糖结构异构体。发现了特征性标记离子，它们可用于连接类型的归属和特定异构体形式的鉴定。该方法用于直接鉴定来自蜂蜜、葡萄酒和牛奶等实际商业产品中的二糖异构体，无需复杂的样品预处理或色谱分离。
