Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Glycobiology. 2010 May;20(5):576-85. doi: 10.1093/glycob/cwq007. Epub 2010 Jan 24.
The addition of glycosylphosphatidylinositol (GPI) anchors to proteins is an important posttranslational modification in eukaryotic cells. The complete structural elucidation of GPI anchors is a complex process that requires relatively large amounts of starting material. In this paper, we assess the degree of structural information that can be obtained by applying electrospray mass spectrometry and tandem mass spectrometry to permethylated GPI glycans prepared from a well-characterized GPI-anchored glycoprotein, the variant surface glycoprotein from Trypanosoma brucei. All GPI glycans contain a non-N-acetylated glucosamine residue, and permethylation leads to the formation of a fixed positive charge on the glycans, in the form of a quaternary amine. The permethylated glycans were detected as M +- Na ions, and tandem mass spectrometry of these ions produced substantial, albeit incomplete, structural information on the branching patterns and linkage types for various GPI glycoforms of the variant surface glycoprotein.
糖基磷脂酰肌醇（GPI）锚定到蛋白质上是真核细胞中一种重要的翻译后修饰。完整的 GPI 锚定结构的阐明是一个复杂的过程，需要相对大量的起始材料。在本文中，我们评估了通过应用电喷雾质谱和串联质谱对从一种经过充分表征的 GPI 锚定糖蛋白（即来自锥虫的变异表面糖蛋白）制备的全甲基化 GPI 聚糖获得的结构信息的程度。所有 GPI 聚糖都含有一个非 N-乙酰化的葡萄糖胺残基，全甲基化导致聚糖上形成固定的正电荷，形式为季铵盐。全甲基化的聚糖被检测为 M+-Na离子，对这些离子的串联质谱产生了关于变异表面糖蛋白的各种 GPI 糖型的分支模式和连接类型的大量（尽管不完整）结构信息。
