Collision-induced dissociation (CID) is by far the most broadly applied dissociation method used for tandem mass spectrometry (MS/MS). This includes MS/MS-based structural interrogation of glycopeptides for applications in glycoproteomics. The end goal of such measurements is to determine the monosaccharide connectivity of the glycan, the amino acid sequence of the peptide, and the site of glycosylation for each glycopeptide of interest. In turn, this allows inferences with respect to the glycoprofile of the intact glycoprotein. For glycopeptide analysis, CID is best known for the ability to determine glycosidic topology of the oligosaccharide group; however, CID has also been shown to produce amide bond cleavage of the polypeptide group. Whether structural information is obtained for the glycan or the peptide has been found to depend on the applied collision energy. While these energy-resolved fragmentation pathways have been the subject of several studies on N-linked glycopeptides, there remains a dearth of similar work on O-linked glycopeptides. In this study, MS/MS via CID was shown to provide substantial peptide backbone fragmentation, in addition to glycosidic fragmentation, in an energy-dependent manner. While qualitatively similar to previous findings for N-glycopeptides, the energy-resolved CID (ER-CID) of O-glycopeptides was found to be substantially more sensitive to the collision energy setting. Thus, deliberately obtaining either glycan or peptide dissociation is a more delicate undertaking for O-glycopeptides. Establishing a more complete understanding of O-glycopeptide ER-CID is likely to have a substantive impact on how O-glycoproteomic analysis is approached in the future.

中文翻译：

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通过能量分辨的Collison诱导的非特异性蛋白水解质子化O-糖肽解离，并行测定多肽和寡糖的连接性。

碰撞诱导解离（CID）是迄今为止用于串联质谱（MS / MS）的最广泛应用的解离方法。这包括基于MS / MS的糖肽结构查询，用于糖蛋白组学。此类测量的最终目标是确定聚糖的单糖连接性，肽的氨基酸序列以及每种目标糖肽的糖基化位点。继而，这允许对完整糖蛋白的糖谱进行推断。对于糖肽分析，CID以确定寡糖基团的糖苷拓扑结构的能力而闻名。但是，CID也已显示可产生多肽基团的酰胺键裂解。已经发现是否获得聚糖或肽的结构信息取决于所施加的碰撞能量。尽管这些能量分辨的断裂途径已经成为对N-连接糖肽的一些研究的主题，但是对于O-连接糖肽的类似工作仍然缺乏。在这项研究中，通过CID的MS / MS被证明除了糖苷片段化以外，还以能量依赖的方式提供了重要的肽主链片段化。虽然在质量上与先前对N-糖肽的发现相似，但发现O-糖肽的能量分辨CID（ER-CID）对碰撞能量设置更为敏感。因此，对于O-糖肽，有意地获得聚糖或肽的解离是更微妙的任务。