DELAYED EXTRACTION ON VISION 2000 REFLECTRON TIME OF FLIGHT MASS SPECTROMETER

ESI-三重四极杆串联质谱（MS/MS） 以前被应用于糖苷键分配， 全甲基化与碱金属阳离子结合的碳水化合物 加合在正模式电离，并提供了两个 灵敏度和广泛的糖苷表征。 但 连锁识别常常受到以下因素的影响 N-乙酰化氨基糖或唾液酸，并通过增加分子量 大小，倾向于促进糖苷片段化的因素， 连锁鉴定所需的开环途径。 先前 研究人员已经通过负模式指定了二糖中的键 电离和低能碰撞。 在这项研究中，连锁分析 通过负模式电喷雾电离（ESI）和三重四极杆 MS/MS扩展到较大的寡糖。 联动识别 通过从还原端进行特定冲销而获得的收益。 虽然 去质子化的起始位点不需要通过还原反应来进行B。 末端，糖苷键的寡糖，没有一个自由的 还原端一般不能确定。

ESI-triple quadrupole tandem mass spectrometry (MS/MS) has previously been applied to glycosidic linkage assignment in carbohydrates by combining permethylation with alkali metal cation adduction in positive mode ionization and has provided both sensitivity and extensive glycosidic characterization. However, the linkage identification is often compromised by the presence of N-acetylated amino sugars or sialic acids and by increasing molecular size, factors which tend to promote glycosidic fragmentation over the ring-opening pathways required for linkage identification. Previous investigators have assigned linkages in disaccharides by negative mode ionization and low energy collisions. In this study, linkage analysis by negative mode electrospray ionization (ESI) and triple quadrupole MS/MS is extended to larger oligosaccharides. Linkage identification proceeds by specific eliminations from the reducing end. Although the initial site of deprotonation is not required to b e the reducing terminal, glycosidic linkages of oligosaccharides without a free reducing end cannot generally be determined.