Viseux N, de Hoffmann E, Domon B
Laboratoire de Spectrométrie de Masse, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
Anal Chem. 1998 Dec 1;70(23):4951-9. doi: 10.1021/ac980443+.
The sequential tandem mass spectrometry (MSn) capabilities offered by quadrupole ion trap instruments have been explored in a systematic study of permethylated oligosaccharides. Under collision-induced dissociation, protonated molecular species generated in the electrospray ionization mode yield simple and predictable mass spectra. Information on sequence, branching, and, to some extent, interglycosidic linkages can be deduced from fragments resulting from the cleavage of glycosidic bonds. Simple rules for the structural assignment of carbohydrates have been established for the fragmentation of protonated species and subunits thereof and corroborated by 18O-labeling experiments. Moreover, sequential tandem mass spectrometry was demonstrated to allow the straightforward structural characterization of unknown carbohydrate moieties by comparing their CID spectra with those of a set of references. As the collision-induced dissociation patterns are not dependent on the number of prior tandem mass spectrometric steps, structures can be unambiguously assigned by match of the spectra. These findings establish the basis of MSn performed on a quadrupole ion trap instrument for elucidating structures of large carbohydrates, which can be virtually degraded in the mass spectrometer into smaller entities in one or several steps. This powerful technique has been applied, used in conjunction with specific CD3 labeling, to the characterization of series of subunits generated from fucosylated and sialylated oligosaccharides, which are among the most important structures as far as biological activities are concerned.
在对全甲基化寡糖的系统研究中，已对四极杆离子阱仪器提供的串联质谱（MSn）功能进行了探索。在碰撞诱导解离下，电喷雾电离模式下产生的质子化分子物种会产生简单且可预测的质谱。关于序列、分支以及在一定程度上糖苷键连接的信息可以从糖苷键断裂产生的碎片中推导出来。针对质子化物种及其亚基的碎片化，已经建立了用于碳水化合物结构归属的简单规则，并通过18O标记实验得到了证实。此外，通过将未知碳水化合物部分的碰撞诱导解离（CID）光谱与一组参考光谱进行比较，串联质谱被证明可以直接对其进行结构表征。由于碰撞诱导解离模式不依赖于先前串联质谱步骤的数量，因此可以通过光谱匹配明确地确定结构。这些发现为在四极杆离子阱仪器上进行MSn以阐明大型碳水化合物结构奠定了基础，这些大型碳水化合物实际上可以在质谱仪中通过一步或几步降解为较小的实体。这项强大的技术已与特定的CD3标记结合应用于对岩藻糖基化和唾液酸化寡糖产生的一系列亚基的表征，就生物活性而言，这些寡糖是最重要的结构之一。
