The role of mobile protons in negative ion CID of oligosaccharides
The role of mobile protons in negative ion CID of oligosaccharides
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DOI：
10.1016/j.jasms.2007.01.016
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发表时间：
2007-05-01
影响因子：
3.2
通讯作者：
Costello, Catherine E.
中科院分区：
文献类型：
--
作者：
Zaia, Joseph;Miller, May Joy C.;Costello, Catherine E.
所有种类的碳水化合物都是由建立在共同核心单位上的糖型混合物组成的。这种混合物的组成和结构的测定在很大程度上依赖于串联质谱数据。对于数量非常少的样品和硫酸盐化的聚糖类，通常需要对天然聚糖进行分析。负串联质谱法（MS）为中性低聚糖提供了有用的产品离子谱图，并优先用于酸性类。在该实验室之前的工作中，已经阐明了唾液化对负模式下产物离子谱的位点特异性影响。目前的结果表明，如何相互作用的两个其他酸性基团，糖醛酸和硫酸盐，决定产物的离子模式硫酸软骨素寡糖。无硫酸软骨素寡糖解离形成c型离子几乎全部。硫酸软骨素寡糖通过糖苷键裂解产生丰富的B型和y型离子，而C型和z型离子丰度较低。这些观察结果是根据在碰撞加热过程中发生的竞争性质子转移反应来解释的。基于串联质谱和产物离子丰度作为碰撞能量的函数，提出了产物离子形成的机理。
Carbohydrates of all classes consist of glycoform mixtures built on common core units. Determination of compositions and structures of such mixtures relies heavily on tandem mass spectrometric data. Analysis of native glycans is often necessary for samples available in very low quantities and for sulfated glycan classes. Negative tandem mass spectrometry (MS) provides useful product ion profiles for neutral oligosaccharides and is preferred for acidic classes. In previous work from this laboratory, site-specific influences of sialylation on product ion profiles in the negative mode were elucidated. The present results show how the interplay of two other acidic groups, uronic acids and sulfates, determines product ion patterns for chondroitin sulfate oligosaccharides. Unsulfated chondroitin oligosaccharides dissociate to form C-type ions almost exclusively. Chondroitin sulfate oligosaccharides produce abundant B- and Y-type ions from glycosidic bond cleavage with C- and Z-types in low abundances. These observations are explained in terms of competing proton transfer reactions that occur during the collisional heating process. Mechanisms for product ion formation are proposed based on tandem mass spectra and the abundances of product ions as a function of collision energy.