Glycosaminoglycans (GAGs) participate in a broad range of physiological processes, and their structures are of interest to researchers in structural biology and medicine. Although they are abundant in tissues and extracellular matrices, their structural heterogeneity makes them challenging analytes. Mass spectrometry, and more specifically, tandem mass spectrometry, is particularly well suited for their analysis. Many tandem mass spectrometry techniques have been examined for their suitability toward the structural characterization of GAGs. Threshold activation methods such as collision-induced dissociation (CID) produce mainly glycosidic cleavages and do not yield a broad range of structurally informative cross-ring fragments. Considerable research efforts have been directed at finding other means of dissociating gas-phase GAG ions to produce more comprehensive structural information. Here, we compare the structural information on GAGs obtained by charge-transfer dissociation (CTD) and electron detachment dissociation (EDD). EDD has previously been applied to GAGs and is known to produce both glycosidic and cross-ring cleavages in similar abundance. CTD has not previously been used to analyze GAGs but has been shown to produce abundant cross-ring cleavages and no sulfate loss when applied to another class of sulfated carbohydrates like algal polysaccharides. In contrast to EDD, which is restricted to FTICR mass spectrometers, CTD can be implemented on other platforms, such as ion trap mass spectrometers (ITMS). Here, we show the capability of CTD-ITMS to produce structurally significant details of the sites of modification in both heparan sulfate (HS) and chondroitin sulfate (CS) standards ranging in length from degree of polymerization (dp) 4 to dp6. EDD and CTD both yield more structural information than CID and yield similar fractional abundances to one another for glycosidic fragments, cross-ring fragments, and neutral losses.

中文翻译：

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使用电荷转移解离对硫酸化糖胺聚糖进行结构表征。


糖胺聚糖 (GAG) 参与广泛的生理过程，其结构引起结构生物学和医学研究人员的兴趣。尽管它们在组织和细胞外基质中含量丰富，但其结构异质性使它们成为具有挑战性的分析物。质谱法，更具体地说，串联质谱法特别适合它们的分析。许多串联质谱技术已被检验其对于 GAG 结构表征的适用性。碰撞诱导解离 (CID) 等阈值激活方法主要产生糖苷裂解，不会产生广泛的结构信息交叉环片段。大量的研究工作致力于寻找解离气相 GAG 离子的其他方法，以产生更全面的结构信息。在这里，我们比较了通过电荷转移解离（CTD）和电子脱离解离（EDD）获得的GAG的结构信息。 EDD 先前已应用于 GAG，并且已知可产生相似丰度的糖苷和交叉环裂解。 CTD 以前从未用于分析 GAG，但已被证明在应用于另一类硫酸化碳水化合物（如藻类多糖）时会产生丰富的跨环裂解，并且不会导致硫酸盐损失。与仅限于 FTICR 质谱仪的 EDD 不同，CTD 可以在其他平台上实施，例如离子阱质谱仪 (ITMS)。在这里，我们展示了 CTD-ITMS 能够生成硫酸乙酰肝素 (HS) 和硫酸软骨素 (CS) 标准品中修饰位点的结构重要细节，长度范围从聚合度 (dp) 4 到 dp6。 EDD 和 CTD 均比 CID 产生更多的结构信息，并且糖苷片段、跨环片段和中性损失的分数丰度彼此相似。