Acta Biochim Biophys Sin (Shanghai). 2024 Aug 8;56(8):1172-1183. doi: 10.3724/abbs.2024133.
linked glycosylation is a common posttranslational modification of proteins that results in macroheterogeneity of the modification site. However, unlike simpler modifications, glycosylation introduces an additional layer of complexity with tens of thousands of possible structures arising from various dimensions, including different monosaccharide compositions, sequence structures, linking structures, isomerism, and three-dimensional conformations. This results in additional microheterogeneity of the modification site of glycosylation, i.e., the same glycosylation site can be modified with different glycans with a certain stoichiometric ratio. glycosylation regulates the structure and function of glycoproteins in a site- and structure-specific manner, and differential expression of glycosylation under disease conditions needs to be characterized through site- and structure-specific quantitative analysis. Numerous advanced methods ranging from sample preparation to mass spectrum analysis have been developed to distinguish N-glycan structures. Chemical derivatization of monosaccharides, online liquid chromatography separation and ion mobility spectrometry enable the physical differentiation of samples. Tandem mass spectrometry further analyzes the macro/microheterogeneity of intact glycopeptides through the analysis of fragment ions. Moreover, the development of search engines and AI-based software has enhanced our understanding of the dissociation patterns of intact glycopeptides and the clinical significance of differentially expressed intact glycopeptides. With the help of these modern methods, structure-specific glycoproteomics has become an important tool with extensive applications in the biomedical field.
糖基化修饰是一种常见的蛋白质翻译后修饰，会导致修饰位点的宏观不均一性。然而，与简单修饰不同，糖基化修饰会引入额外的复杂性，其可能结构有数千种，这源于各种维度，包括不同的单糖组成、序列结构、连接结构、异构现象和三维构象。这导致糖基化修饰位点的额外微观不均一性，即相同的糖基化位点可以用具有一定化学计量比的不同聚糖进行修饰。糖基化修饰以位点和结构特异性的方式调节糖蛋白的结构和功能，在疾病条件下，糖基化的差异表达需要通过位点和结构特异性定量分析来进行特征描述。已经开发了许多从样品制备到质谱分析的先进方法来区分 N-聚糖结构。单糖的化学衍生化、在线液相色谱分离和离子淌度谱使样品的物理分离成为可能。串联质谱通过分析碎片离子进一步分析完整糖肽的宏/微观不均一性。此外，搜索引擎和基于人工智能的软件的发展增强了我们对完整糖肽解离模式的理解以及差异表达的完整糖肽的临床意义。借助这些现代方法，结构特异性糖蛋白质组学已成为生物医学领域中具有广泛应用的重要工具。
