To understand the biological relevance of glycans, many mass spectrometry (MS)‐based methods have been developed for the relative quantification of N‐linked glycans using stable isotopic labeling. The increasing demand for the simultaneous comparative quantification of N‐linked glycans for samples of various biological conditions is a new challenge for MS. We proposed a novel relative quantitative glycomics that enzymatically incorporates isotope‐labeled glucose into N‐linked glycans through transglycosylation of endo‐β‐N‐acetylglucosaminidase M (Endo‐M) and isotope‐labeled glucose. Newly incorporated normal (light) and isotope‐labeled (heavy) N‐linked glycans were synthesized using the same known concentration of sialyglycopeptide, and their relative quantitative properties were realized from the duplex mass spectrum. In addition, the dynamic range and accuracy of the relative quantification were shown with light and heavy N‐linked glycans for sialyglycopeptide at a constant concentration ratio.

中文翻译：

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Endo-M和同位素葡萄糖的转糖基化对N-连接的聚糖进行同位素标记以进行定量糖

为了了解聚糖的生物学相关性，已开发出许多基于质谱（MS）的方法，用于使用稳定的同位素标记对N连接的聚糖进行相对定量。对于各种生物学条件下的样品，同时比较N-连接聚糖的同时定量的需求不断增加，这是MS面临的新挑战。我们提出了一种新型的相对定量糖组学，该酶通过内β - N-乙酰氨基葡糖苷酶M（Endo-M）和同位素标记的葡萄糖的转糖基作用，将同位素标记的葡萄糖酶合并到N-连接的聚糖中。新加入的正常（轻）和同位素标记（重）N使用相同的已知浓度唾液酸糖肽合成了连接的聚糖，并通过双工质谱实现了它们的相对定量特性。此外，在恒定浓度比下，唾液酸糖肽的轻链和重链N链聚糖显示了相对定量的动态范围和准确性。