Metelmann W, Vukelić Z, Peter-Katalinić J
Laboratory for Biomedical Analysis, Institute for Medical Physics and Biophysics, University of Münster, Robert-Koch-Str. 31, D-48149 Münster, Germany.
J Mass Spectrom. 2001 Jan;36(1):21-9. doi: 10.1002/jms.100.
A general approach for the detection and structural elucidation of brain ganglioside species GM1, GD1 and GT1 by nano-electrospray ionization quadrupole time-of-flight (nanoESI-QTOF) mass spectrometry (MS), using combined data from MS and MS/MS analysis of isolated native ganglioside fractions in negative ion mode and their permethylated counterparts in the positive ion mode is presented. This approach was designed to detect and sequence gangliosides present in preparatively isolated ganglioside fractions from pathological brain samples available in only very limited amounts. In these fractions mixtures of homologue and isobaric structures are present, depending on the ceramide composition and the position of the sialic acid attachment site. The interpretation of data for the entire sequence, derived from A, B, C and Y ions by nanoESI-QTOFMS/MS in the negative ion mode of native fractions, can be compromised by ions arising from double and triple internal cleavages. To distinguish between isobaric carbohydrate structures in gangliosides, such as monosialogangliosides GM1a and GM1b, disialogangliosides GD1a, GD1b and GD1c or trisialogangliosides GT1b, GT1c and GT1d, the samples were analysed after permethylation in the positive ion nanoESI-QTOFMS/MS mode, providing set of data, which allows a clear distinction for assignment of outer and inner fragment ions according to their m/z values. The fragmentation patterns from native gangliosides obtained by low-energy collision induced dissociation (CID) by nanoESI-QTOF show common behaviour and follow inherent rules. The combined set of data from the negative and positive ion mode low-energy CID can serve for the detection of structural isomers in mixtures, and to trace new, not previously detected, components.
本文介绍了一种通过纳米电喷雾电离四极杆飞行时间质谱（nanoESI-QTOF）检测和结构解析脑苷脂GM1、GD1和GT1的通用方法，该方法使用负离子模式下分离的天然神经节苷脂组分及其正离子模式下的全甲基化对应物的质谱和串联质谱分析的组合数据。这种方法旨在检测和测序仅以非常有限量获得的病理性脑样本中制备分离的神经节苷脂组分中存在的神经节苷脂。在这些组分中，根据神经酰胺组成和唾液酸连接位点的位置，存在同系物和等压结构的混合物。在负离子模式下，通过nanoESI-QTOFMS/MS从天然组分的A、B、C和Y离子获得的整个序列的数据解释可能会受到双内部裂解和三内部裂解产生的离子的影响。为了区分神经节苷脂中的等压碳水化合物结构，如单唾液酸神经节苷脂GM1a和GM1b、双唾液酸神经节苷脂GD1a、GD1b和GD1c或三唾液酸神经节苷脂GT1b、GT1c和GT1d，在正离子nanoESI-QTOFMS/MS模式下对全甲基化后的样品进行分析，提供了一组数据，该数据允许根据其m/z值清楚地区分外部和内部碎片离子。通过nanoESI-QTOF的低能碰撞诱导解离（CID）获得的天然神经节苷脂的裂解模式显示出共同的行为并遵循内在规则。负离子和正离子模式低能CID的组合数据集可用于检测混合物中的结构异构体，并追踪新的、以前未检测到的成分。
