DEVELOPMENT OF IMPROVED METHODS FOR CARBOHYDRATE SEQUENCING

使用四极离子阱（qIT）质量的电喷雾电离（ES） 分析器被认为是一种改进的仪器方法 了解碳水化合物结构的细节。 评价这一 功能，在BUSM资源处准备了多个样本， 带到成功使用LCQ的实验室（Finnigan） 保罗离子阱。 样品，包括GSL、N-和0-连接聚糖， 从糖蛋白中提取或释放出来，并被甲基化。 广泛 努力集中在复杂聚糖的内部核心分支上， 确定链接详细信息。 两篇论文描述了这项工作已经 接受出版。 在一份报告中， 对鞘糖脂样品的s6序列、分支 和链接信息。 得到的结果是定性的， 与三重四极杆仪器（Qlq 2 Q3）相当， 来自C1-O糖苷断裂的碳水化合物片段和另外的 提供鞘氨醇和N-酰基测定的片段 神经酰胺部分的异质性。 然而，与此形成鲜明对比的是， QIT通过MS的研究扩展了对碳水化合物的理解 首次提供了吡喃交叉环裂解， 糖脂残基间键结构。 这是通过 - 选择次级碎片（MS 3），其不含能量汇， 容易的键断裂主导产物离子光谱。 分离与 这些亚结构的激活导致更均匀的 碎片的分布，提供以前的结构见解 无法通过串联质谱法获得。 在研究中， 分支聚糖，MS暴露的结构特征的特征不 可与串联仪器，并从糖蛋白 胎球蛋白，澄清了三触角分支中存在的争议 topology. 这项技术似乎提供了一个重要的步骤， 为了理解碳水化合物结构的各个方面， 在一个单一的工具。

Electrospray ionization (ES) with a quadrupole ion trap (qIT) mass analyzer has been considered to be an improved instrumental approach to understand the details of carbohydrate structure. To evaluate this feature, multiple samples were prepared at the BUSM Resource and brought to laboratories that were successfully using a LCQ (Finnigan) Paul ion trap. Samples, including GSL, N-, and 0-linked glycans were extracted or released from glycoproteins, andmethylated. Extensive effort was focused on internal core branching of complex glycans to ascertain linkage detail. Two papers describing this work have been accepted for, publication. In onereport, an isomeric disialyl glycosphingolipid samples was evaluated for s6quence, branching andlinkage information. Results were obtained that were qualitatively comparable with triple quadrupole instruments (Qlq2Q3) with major carbohydrate fragments from CI-O glycosidic rupture and additional fragments that provided a determination of sphingosine and N-acyl heterogeneity of the ceramide moiety. In unique contrast, however, the qIT extended carbohydrate understanding through MS' studies providing for the first time pyran cross-ring cleavages that define inter-residue linkage structure for glycolipids. This was achieved by selecting secondary fragments (MS3), free from the energy sinks of facile bond rupture that dominate product ion spectra. Isolation and activation of these substructures result in a more uniform distribution of fragments, providing structural insights previously inaccessible by tandem mass spectrometry. In studies with complex and branched glycans, the feature of MS' exposed structural features not available with tandem instrumentation, and from the glycoprotein fetuin, clarified an existing controversy in triantennary branching topology. This technology appears to provide a significant step toward the goal of understanding aH aspects of carbohydrate structure in a single instrument.