Firdoussi Ahlam El, Lafitte Marie, Tortajada Jeanine, Kone Omar, Salpin Jean-Yves
Université d'Evry Val d'Essonne--Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, CNRS, Bâtiment Maupertuis, Boulevard François Mitterrand, 91025 EVRY, France.
J Mass Spectrom. 2007 Aug;42(8):999-1011. doi: 10.1002/jms.1220.
Electrospray ionization in combination with tandem mass spectrometry and lead cationization is used to characterize the linkage position of underivatized disaccharides. Lead(II) ions react mainly with disaccharides by proton abstraction to generate Pb(disaccharide)(m)-H ions (m = 1-2). At low cone voltages, an intense series of doubly charged ions of general formula Pb(disaccharide)(n) are also observed. Our study shows that MS/MS experiments have to be performed to differentiate Pb(2+)-coordinated disaccharides. Upon collision, Pb(disaccharide)-H species mainly dissociate according to glycosidic bond cleavage and cross-ring cleavages, leading to the elimination of C(n)H(2n)O(n) neutrals (n = 2-4). The various fragmentation processes allow the position of the glycosidic bond to be unambiguously located. Distinction between glc-glc and glc-fru disaccharides also appears straightforward. Furthermore, for homodimers of D-glucose our data demonstrate that the anomericity of the glycosidic bond can be characterized for the 1 --> n linkages (n = 2, 4, 6). Consequently, Pb(2+) cationization combined with tandem mass spectrometry appears particularly useful to identify underivatized disaccharides.
电喷雾电离结合串联质谱和铅阳离子化用于表征未衍生化二糖的连接位置。铅（II）离子主要通过质子提取与二糖反应，生成Pb（二糖）（m）-H离子（m = 1 - 2）。在低锥电压下，还观察到一系列通式为Pb（二糖）（n）的强双电荷离子。我们的研究表明，必须进行串联质谱实验以区分与Pb(2+)配位的二糖。碰撞时，Pb（二糖）-H物种主要根据糖苷键断裂和跨环断裂进行解离，导致消除C(n)H(2n)O(n)中性分子（n = 2 - 4）。各种碎裂过程使得糖苷键的位置能够明确确定。葡萄糖-葡萄糖和葡萄糖-果糖二糖之间的区分也似乎很直接。此外，对于D-葡萄糖的同二聚体，我们的数据表明糖苷键的异头构型可以针对1→n连接（n = 2、4、6）进行表征。因此，Pb(2+)阳离子化结合串联质谱对于鉴定未衍生化二糖显得特别有用。
