The stereochemical dependence of unimolecular dissociation of monosaccharide-glycolaldehyde anions in the gas phase: a basis for assignment of the stereochemistry and anomeric configuration of monosaccharides in oligosaccharides by mass spectrometry via a key discriminatory product ion of disacchari
The stereochemical dependence of unimolecular dissociation of monosaccharide-glycolaldehyde anions in the gas phase: a basis for assignment of the stereochemistry and anomeric configuration of monosaccharides in oligosaccharides by mass spectrometry via a key discriminatory product ion of disacchari
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气相中单糖-乙醇醛阴离子单分子解离的立体化学依赖性：通过二糖的关键判别产物离子通过质谱法分配寡糖中单糖的立体化学和端基异构构型的基础
DOI：
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发表时间：
2007
影响因子：
15
通讯作者：
B. Bendiak
中科院分区：
文献类型：
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作者：
T. Fang;B. Bendiak
含己糖的二糖的质谱通常在负离子模式下产生m/z 221的产物离子。使用保罗陷阱，隔离和碰撞诱导解离的m/z 221阴离子产生的质谱，很容易区分其立体化学和异头构型，所有16个立体化学变体。通过标准品的化学合成，证明离子是吡喃葡萄糖基-乙醇醛。立体化学显著影响断裂，这取决于四种相对立体化学排列：（1）2位的羟基与异头构型之间的关系，（2）异头位置与2位和3位的顺式关系（1，2，3-顺式），（3）1，2反式-2，3顺式关系，和（4）4位羟基与异头构型之间的关系。标记后的还原羰基氧的一系列二糖与18 O质量区分其单糖组分，它被证明，m/z 221阴离子是由一个完整的非还原糖糖苷连接到一个2-碳糖苷配基来自还原糖，无论单糖之间的连接位置。这使得完整糖的位置被分配到糖苷键的非还原侧。重现性所需的实验因素的详细研究表明，每个m/z 221阴离子的独特质谱可以通过使用内部能量输入校准离子，确保可重现的能量沉积到离子中，每月获得。2-乙酰氨基-2-脱氧己糖的这些离子的对应物是m/z 262阴离子，并且这些阴离子的异头构型和立体化学也可以重复地区分N-乙酰葡糖胺和N-乙酰半乳糖胺。m/z 221阴离子的断裂模式提供了一个坚实的可重复的基础，在气相中的糖立体化学的分配。
Mass spectrometry of hexose-containing disaccharides often yields product ions of m/z 221 in the negative ion mode. Using a Paul trap, isolation and collision-induced dissociation of the m/z 221 anions yielded mass spectra that easily differentiated their stereochemistry and anomeric configuration, for all 16 stereochemical variants. The ions were shown to be glycopyranosyl-glycolaldehydes through chemical synthesis of their standards. The stereochemistry dramatically affected fragmentation which was dependent on four relative stereochemical arrangements: (1) the relationship between the hydroxyl group at position 2 and the anomeric configuration, (2) a cis relationship of the anomeric position and positions 2 and 3 (1,2,3-cis), (3) a 1,2 trans-2,3 cis relationship, and (4) the relationship between the hydroxyl group at position 4 and the anomeric configuration. After labeling the reducing carbonyl oxygen of a series of disaccharides with 18O to mass-discriminate between their monosaccharide components, it was demonstrated that m/z 221 anions are comprised of an intact nonreducing sugar glycosidically linked to a 2-carbon aglycon derived from the reducing sugar, irrespective of the linkage position between monosaccharides. This enabled the location of the intact sugar to be assigned to the nonreducing side of a glycosidic linkage. Detailed studies of experimental factors necessary for reproducibility demonstrated that the unique mass spectrum for each m/z 221 anion could be obtained from month-to-month through the use of an internal energy-input calibrant ion that ensured reproducible energy deposition into the ions. The counterparts to these ions for the 2-acetamido-2-deoxyhexoses were m/z 262 anions, and the anomeric configuration and stereochemistry of these anions could also be reproducibly discriminated for N-acetylglucosamine and N-acetylgalactosamine. The fragmentation patterns of m/z 221 anions provide a firm reproducible basis for assignment of sugar stereochemistries in the gas phase.