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Anal Chem. 2016 Jun 7;88(11):5904-13. doi: 10.1021/acs.analchem.6b00819. Epub 2016 May 23.

Linkage-Specific in Situ Sialic Acid Derivatization for N-Glycan Mass Spectrometry Imaging of Formalin-Fixed Paraffin-Embedded Tissues.

Author information

1
Center for Proteomics and Metabolomics, Leiden University Medical Center , Leiden 2333 ZA, The Netherlands.
2
Department of Pathology, Leiden University Medical Center , Leiden 2333 ZA, The Netherlands.
3
Department of Surgery, Leiden University Medical Center , Leiden 2333 ZA, The Netherlands.
4
Department of Microbiology and Immunology, Drexel University College of Medicine , 245 N. 15th Street, Philadelphia, Pennsylvania 19102, United States.
5
Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina , Charleston, South Carolina 29425, United States.
6
Fondazione Pisana per la Scienza ONLUS, c/o Croce Rossa Italiana , via Panfilo Castaldi 2, 56121, Ospedaletto, Pisa, Italy.

Abstract

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.

PMID:
27145236
DOI:
10.1021/acs.analchem.6b00819
[Indexed for MEDLINE]

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