MALDI MS In-Source Decay of Glycans Using a Glutathione-Capped Iron Oxide Nanoparticle Matrix
MALDI MS In-Source Decay of Glycans Using a Glutathione-Capped Iron Oxide Nanoparticle Matrix
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DOI：
10.1021/ac502422a
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发表时间：
2014-08-19
影响因子：
7.4
通讯作者：
Cassady, Carolyn J.
中科院分区：
文献类型：
--
作者：
Liang, Qiaoli;Macher, Thomas;Cassady, Carolyn J.
提出了一种新的基质辅助激光解吸电离（MALDI）质谱矩阵用于聚糖分子质量和结构的测定。该基质含有氧化铁纳米颗粒（NP）核心，谷胱甘肽（GSH）分子共价结合到表面。如单糖葡萄糖和几种较大聚糖所示，质谱显示出良好的分析物离子强度和信噪比，以及低质荷比（m/z）区域中异常干净的背景。此外，当激光功率增加到电离阈值以上时，会发生丰富的源内衰减（ISD）;这表明基质向样品提供了强能量转移。对于五个模型聚糖，ISD产生了广泛的糖苷和交叉环裂解的正离子模式，从单电荷的前体离子与绑定钠离子。采用线性、支链和环状聚糖，并且发现所有这些都通过ISD进行大量片段化。O-18标记用于澄清m/z归属模糊性，并表明大部分片段来自聚糖的非还原末端。对全乙酰化聚糖的研究表明，即使在不存在羟基的情况下，也会发生大量的ISD片段化。使用这种新基质产生的ISD产物离子应证明在聚糖测序中有用。
A new matrix-assisted laser desorption ionization (MALDI) mass spectrometry matrix is proposed for molecular mass and structural determination of glycans. This matrix contains an iron oxide nanoparticle (NP) core with gluthathione (GSH) molecules covalently bound to the surface. As demonstrated for the monosaccharide glucose and several larger glycans, the mass spectra exhibit good analyte ion intensities and signal-to-noise ratios, as well as an exceptionally clean background in the low mass-to-charge (m/z) region. In addition, abundant in-source decay (ISD) occurs when the laser power is increased above the ionization threshold; this indicates that the matrix provides strong energy transfer to the sample. For five model glycans, ISD produced extensive glycosidic and cross-ring cleavages in the positive ion mode from singly charged precursor ions with bound sodium ions. Linear, branched, and cyclic glycans were employed, and all were found to undergo abundant fragmentation by ISD. O-18 labeling was used to clarify m/z assignment ambiguities and showed that the majority of the fragmentation originates from the nonreducing ends of the glycans. Studies with a peracetylated glycan indicated that abundant ISD fragmentation occurs even in the absence of hydroxyl groups. The ISD product ions generated using this new matrix should prove useful in the sequencing of glycans.