Among dissociation methods, negative electron transfer dissociation (NETD) has been proven the most useful for glycosaminoglycan (GAG) sequencing because it produces informative fragmentation, a low degree of sulfate losses, high sensitivity, and translatability to multiple instrument types. The challenge, however, is to distinguish positional sulfation. In particular, NETD has been reported to fail to differentiate 4-O- versus 6-O-sulfation in chondroitin sulfate decasaccharide. This raised the concern of whether NETD is able to differentiate the rare 3-O-sulfation from predominant 6-O-sulfation in heparan sulfate (HS) oligosaccharides. Here, we report that NETD generates highly informative spectra that differentiate sites of O-sulfation on glucosamine residues, enabling structural characterizations of synthetic HS isomers containing 3-O-sulfation. Further, lyase-resistant 3-O-sulfated tetrasaccharides from natural sources were successfully sequenced. Notably, for all of the oligosaccharides in this study, the successful sequencing is based on NETD tandem mass spectra of commonly observed deprotonated precursor ions without derivatization or metal cation adduction, simplifying the experimental workflow and data interpretation. These results demonstrate the potential of NETD as a sensitive analytical tool for detailed, high-throughput structural analysis of highly sulfated GAGs. Graphical Abstract.

中文翻译：

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含3-O-硫酸化的乙酰肝素硫酸寡糖的负电子转移解离序列。

在解离方法中，负电子转移解离（NETD）已被证明对糖胺聚糖（GAG）测序最有用，因为它会产生信息性碎片，硫酸盐损失程度低，灵敏度高以及可转换为多种仪器类型。然而，挑战在于区分位置硫酸化。特别是，据报道，NETD无法区分硫酸软骨素十糖中的4-O-和6-O-硫酸化。这引起了人们对NETD是否能够区分硫酸乙酰肝素（HS）寡糖中稀有的3-O-硫酸盐与主要的6-O-硫酸盐的担忧。在这里，我们报道NETD生成了高度有用的光谱，该光谱区分了氨基葡萄糖残基上O-硫酸化的位点，可以对包含3-O-硫酸化的合成HS异构体进行结构表征。此外，成功地测序了天然来源的抗裂解酶的3-O-硫酸化四糖。值得注意的是，对于本研究中的所有寡糖，成功的测序均基于通常观察到的去质子化前体离子的NETD串联质谱，而没有衍生化或金属阳离子加合，简化了实验工作流程和数据解释。这些结果证明了NETD作为灵敏的分析工具进行高硫酸化GAG的详细，高通量结构分析的潜力。图形概要。成功的测序基于NETD串联质谱，该质谱通常观察到的去质子化的前驱体离子没有衍生化或金属阳离子加合，从而简化了实验工作流程和数据解释。这些结果证明了NETD作为灵敏的分析工具进行高硫酸化GAG的详细，高通量结构分析的潜力。图形概要。成功的测序基于NETD串联质谱，该质谱通常观察到的去质子化的前驱体离子没有衍生化或金属阳离子加合，从而简化了实验工作流程和数据解释。这些结果证明了NETD作为灵敏的分析工具进行高硫酸化GAG的详细，高通量结构分析的潜力。图形概要。