Ashline David, Singh Suddham, Hanneman Andy, Reinhold Vernon
Center for Structural Biology, Department of Chemistry, University of New Hampshire, Durham, New Hampshire 03824, USA.
Anal Chem. 2005 Oct 1;77(19):6250-62. doi: 10.1021/ac050724z.
This report is the first in a series of three focused on establishing congruent strategies for carbohydrate sequencing. The reports are divided into (i) analytical considerations that account for all aspects of small oligomer structure by MSn disassembly, (ii) database support using an ion fragment library and associated tools for high-throughput analysis, and (iii) a concluding algorithm for defining oligosaccharide topology from MSn disassembly pathways. The analytical contribution of this first report explores the limits of structural detail exposed by ion trap mass spectrometry with samples prepared as methyl derivatives and analyzed as metal ion adducts. This data mining effort focuses on correlating the fragments of small oligomers to stereospecific glycan structures, an outcome attributed to a combination of metal ion adduction and analyte conformation. Facile glycosidic cleavage introduces a point of lability (pyranosyl-1-ene) that upon collisional activation initiates subsequent ring fragmentation. Product masses and ion intensities vary with interresidue linkage, branching position, and monomer stereochemistry. Excessive fragmentation is the property of small oligomers where collisional energy within a smaller number of oscillators dissipates through extensive fragmentation. The procedures discussed in this report are unified into a singular strategy using an ion trap mass spectrometer with the sensitivity expected for electron multiplier detection. Although a small set of structures have been discussed, the basic principles considered are fully congruent, with ample opportunities for expansion.
本报告是关于建立碳水化合物测序一致策略的系列三篇报告中的第一篇。这些报告分为：（i）通过MSn解离分析小寡聚物结构各方面的分析考量；（ii）使用离子碎片库和相关高通量分析工具的数据库支持；（iii）根据MSn解离途径定义寡糖拓扑结构的最终算法。第一篇报告的分析贡献探讨了以甲基衍生物形式制备并作为金属离子加合物进行分析的样品，通过离子阱质谱法所揭示的结构细节极限。这项数据挖掘工作着重于将小寡聚物的碎片与立体特异性聚糖结构相关联，这一结果归因于金属离子加合和分析物构象的综合作用。容易发生的糖苷键裂解引入了一个不稳定点（吡喃糖基-1-烯），在碰撞激活时会引发后续的环裂解。产物质量和离子强度随残基间连接、分支位置和单体立体化学而变化。过度裂解是小寡聚物的特性，其中较少数量振荡器内的碰撞能量通过广泛裂解而耗散。本报告中讨论的程序通过使用具有电子倍增器检测预期灵敏度的离子阱质谱仪统一为一种单一策略。尽管已经讨论了一小部分结构，但所考虑的基本原理完全一致，有充分的扩展机会。
