Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
Mol Cell Proteomics. 2013 Apr;12(4):979-90. doi: 10.1074/mcp.M112.026880. Epub 2013 Feb 21.
The highly sulfated glycosaminoglycan oligosaccharides derived from heparin and heparan sulfate have been a highly intractable class of molecules to analyze by tandem mass spectrometry. Under the many methods of ion activation, this class of molecules generally exhibits SO3 loss as the most significant fragmentation pathway, interfering with the assignment of the location of sulfo groups in glycosaminoglycan chains. We report here a method that stabilizes sulfo groups and facilitates the complete structural analysis of densely sulfated (two or more sulfo groups per disaccharide repeat unit) heparin and heparan sulfate oligomers. This is achieved by complete removal of all ionizable protons, either by charging during electrospray ionization or by Na(+)/H(+) exchange. The addition of millimolar levels of NaOH to the sample solution facilitates the production of precursor ions that meet this criterion. This approach is found to work for a variety of heparin sulfate oligosaccharides derived from natural sources or produced by chemoenzymatic synthesis, with up to 12 saccharide subunits and up to 11 sulfo groups.
高度硫酸化的糖胺聚糖寡糖衍生自肝素和硫酸乙酰肝素，一直是串联质谱分析的高度难以处理的分子类别。在多种离子激活方法中，此类分子通常表现出 SO3 损失作为最显著的碎片化途径，干扰糖胺聚糖链中硫酸基团位置的分配。我们在此报告一种方法，该方法稳定了硫酸基团并促进了高度硫酸化的（每个二糖重复单元有两个或更多个硫酸基团）肝素和硫酸乙酰肝素低聚物的完整结构分析。这是通过在电喷雾电离过程中充电或通过 Na(+)/H(+) 交换来完全去除所有可电离质子来实现的。向样品溶液中添加毫摩尔水平的 NaOH 有助于产生符合此标准的前体离子。该方法适用于各种源自天然来源或通过化学酶合成产生的硫酸乙酰肝素低聚糖，具有多达 12 个糖基单元和多达 11 个硫酸基团。
