Center for Proteomics and Metabolomics, Leiden University Medical Center , Leiden 2333 ZA, The Netherlands.
Department of Pathology, Leiden University Medical Center , Leiden 2333 ZA, The Netherlands.
Anal Chem. 2016 Jun 7;88(11):5904-13. doi: 10.1021/acs.analchem.6b00819. Epub 2016 May 23.
Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging is a rapidly evolving field in which mass spectrometry techniques are applied directly on tissues to characterize the spatial distribution of various molecules such as lipids, protein/peptides, and recently also N-glycans. Glycans are involved in many biological processes and several glycan changes have been associated with different kinds of cancer, making them an interesting target group to study. An important analytical challenge for the study of glycans by MALDI mass spectrometry is the labile character of sialic acid groups which are prone to in-source/postsource decay, thereby biasing the recorded glycan profile. We therefore developed a linkage-specific sialic acid derivatization by dimethylamidation and subsequent amidation and transferred this onto formalin-fixed paraffin-embedded (FFPE) tissues for MALDI imaging of N-glycans. Our results show (i) the successful stabilization of sialic acids in a linkage specific manner, thereby not only increasing the detection range, but also adding biological meaning, (ii) that no noticeable lateral diffusion is induced during to sample preparation, (iii) the potential of mass spectrometry imaging to spatially characterize the N-glycan expression within heterogeneous tissues.
基质辅助激光解吸/电离（MALDI）质谱成像技术是一个快速发展的领域，它直接将质谱技术应用于组织，以分析各种分子（如脂质、蛋白质/肽，以及最近的 N-聚糖）的空间分布。聚糖参与了许多生物过程，并且已经有几种聚糖变化与不同类型的癌症相关，使它们成为一个有趣的研究目标群体。MALDI 质谱研究聚糖的一个重要分析挑战是唾液酸基团的不稳定性，它们容易在源内/源后发生衰减，从而使记录的聚糖谱发生偏倚。因此，我们通过二甲酰胺化和随后的酰胺化开发了一种特定连接的唾液酸衍生化，并将其转移到福尔马林固定石蜡包埋（FFPE）组织上，用于 N-聚糖的 MALDI 成像。我们的结果表明：（i）成功地以特定连接的方式稳定了唾液酸，从而不仅增加了检测范围，而且增加了生物学意义；（ii）在样品制备过程中没有明显的侧向扩散；（iii）质谱成像技术在空间上对异质组织中 N-聚糖表达进行特征分析的潜力。
