Glycosylation is one of the most significant and abundant posttranslational modifications in mammalian cells. It mediates a wide range of biofunctions, including cell adhesion, cell communication, immune cell trafficking, and protein stability. Also, aberrant glycosylation has been associated with various diseases such as diabetes, Alzheimer's disease, inflammation, immune deficiencies, congenital disorders, and cancers. The alterations in the distributions of glycan and glycopeptide isomers are involved in the development and progression of several human diseases. However, the microheterogeneity of glycosylation brings a great challenge to glycomic and glycoproteomic analysis, including the characterization of isomers. Over several decades, different methods and approaches have been developed to facilitate the characterization of glycan and glycopeptide isomers. Mass spectrometry (MS) has been a powerful tool utilized for glycomic and glycoproteomic isomeric analysis due to its high sensitivity and rich structural information using different fragmentation techniques. However, a comprehensive characterization of glycan and glycopeptide isomers remains a challenge when utilizing MS alone. Therefore, various separation methods, including liquid chromatography, capillary electrophoresis, and ion mobility, were developed to resolve glycan and glycopeptide isomers before MS. These separation techniques were coupled to MS for a better identification and quantitation of glycan and glycopeptide isomers. Additionally, bioinformatic tools are essential for the automated processing of glycan and glycopeptide isomeric data to facilitate isomeric studies in biological cohorts. Here in this review, we discuss commonly employed MS-based techniques, separation hyphenated MS methods, and software, facilitating the separation, identification, and quantitation of glycan and glycopeptide isomers.

中文翻译：

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基于 MS 的糖组学和糖蛋白组学方法可实现异构表征

糖基化是哺乳动物细胞中最重要和最丰富的翻译后修饰之一。它介导广泛的生物功能，包括细胞粘附、细胞通讯、免疫细胞运输和蛋白质稳定性。此外，异常糖基化与多种疾病有关，例如糖尿病、阿尔茨海默病、炎症、免疫缺陷、先天性疾病和癌症。聚糖和糖肽异构体分布的改变与多种人类疾病的发生和发展有关。然而，糖基化的微观异质性给糖组学和糖蛋白组学分析带来了巨大挑战，包括异构体的表征。几十年来，已经开发了不同的方法和方法来促进聚糖和糖肽异构体的表征。质谱 (MS) 已成为用于糖组学和糖蛋白组学异构分析的强大工具，因为它使用不同的碎裂技术具有高灵敏度和丰富的结构信息。然而，单独使用 MS 时，聚糖和糖肽异构体的全面表征仍然是一个挑战。因此，开发了各种分离方法，包括液相色谱、毛细管电泳和离子淌度，以在 MS 之前解决聚糖和糖肽异构体。这些分离技术与 MS 联用，可以更好地鉴定和定量聚糖和糖肽异构体。此外，生物信息学工具对于自动处理聚糖和糖肽异构数据以促进生物队列中的异构研究至关重要。在这篇综述中，我们讨论了常用的基于 MS 的技术、分离联用 MS 方法和软件，以促进聚糖和糖肽异构体的分离、鉴定和定量。