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Mass spectrometry of oligosaccharides

Authors

  • Joseph Zaia

    Corresponding author
    1. Department of Biochemistry, Boston University School of Medicine, 715 Albany St., R-806, Boston, Massachusetts 02118
    • Department of Biochemistry, Boston University School of Medicine, 715 Albany St., R-806, Boston, MA 02118.
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Abstract

I.Introduction162
 II.CHARACTERISTICS OF TANDEM MASS SPECTRA OF CARBOHYDRATES163
 A.  Ionization of Carbohydrates163
     1.  Electrospray Ionization (ESI)163
     2.  Matrix-Assisted Laser Desorption/Ionization (MALDI)163
 B.  Nomenclature for the Fragmentation of Glycoconjugates164
 C.  Tandem MS of Native Oligosaccharide Molecular Ions165
     1.  Protonated Ions165
     2.  Deprotonated Ions166
     3.  Alkali and Alkaline Earth Adducted Ions166
 D.  Tandem MS of Permethylated and Peracetylated Oligosaccharides 169
 E.  Tandem MS of Reductively Aminated Carbohydrates 170
 F.  Discrimination of Monosaccharide Linkages 171
 G.  Gas-Phase Degradation of Oligosaccharides178
 H.  Computer-Based Approaches for Interpretation of Oligosaccharide Product-Ion Mass Spectra181
 I.  Internal Residue Loss Rearrangements of Oligosaccharide Ions During CID 183
 J.  Conclusions 184
 III.ANALYZERS FOR MASS SPECTROMETRY OF CARBOHYDRATES186
 A.  Analysis of Permethylated Carbohydrates Using High Temperature GC/MS 186
 B.  Analysis of Carbohydrates with MALDI-TOF MS 186
 C.  Analysis of Carbohydrates with MALDI Q-oTOF MS 187
 D.  Analysis of Carbohydrates with ESI Q-oTOF MS 187
 E.  Analysis of Carbohydrates with QIT MS 187
 F.  Analysis of Glycoconjugates with FT MS 188
 G.  Conclusions188
 IV.TANDEM MASS SPECTROMETRY OF GLYCOPEPTIDES189
 A.  Ionization of Glycopeptides189
 B.  CID of Glycopeptides190
     1.  Selective Identification of Glycopeptides with Tandem MS 190
     2.  CID of O-Linked Glycopeptides 191
     3.  CID of N-Linked Glycopeptides 191
 C.  Electron Capture Dissociation of Glycopeptides 193
 D.  Conclusions 193
 V.MASS SPECTROMETRY OF SIALYLATED GLYCOCONJUGATES195
 A.  Permethylation of Sialylated Oligosaccharides195
 B.  MALDI-MS of Sialylated Glycoconjugates195
     1.  Anionic Dopants for Analysis of Sialylated Glycoconjugates196
     2.  Methyl Esterification to Stabilize Sialic Acid Residues196
     3.  Perbenzolylation to Stabilize Sialic Acid Residues196
     4.  High-Pressure MALDI of Sialylated Glycoconjugates196
 C.  ESI MS of Sialylated Oligosaccharides 197
 D.  Tandem MS of Sialylated Oligosaccharides198
 E.  Conclusions199
 VI.MASS SPECTROMETRY OF SULFATED OLIGOSACCHARIDES199
 A.  Derivatization199
 B.  Ionization Methods199
     1.  Fast Atom Bombardment199
     2.  MALDI202
         a.  MALDI of Sulfated Peptides202
         b.  Direct MALDI of Sulfated Oligosaccharides202
         c.  Use of Basic Peptides for MALDI of Polysulfated Oligosaccharides 203
         d.  MALDI Analysis of Protein-Sulfated Oligosaccharide Complexes204
     3.  ESI of Sulfated Oligosaccharides205
     4.  On-Line Separation Systems for Sulfated Carbohydrates206
 C.  Tandem MS of Sulfated Oligosaccharides206
     1.  Lessons from CID of Sulfated Peptides206
     2.  Tandem MS of Mono- and Di-Sulfated Oligosaccharides207
     3.  Precursor-Ion and Neutral-Loss Scans for Sulfated Glycoconjugates208
     4.  Determination of Positional Sulfation Isomers in GAG Disaccharides208
     5.  Tandem Mass Spectrometric Quantification of GAG Disaccharides209
     6.  Tandem Mass Spectrometric Analysis of GAG Oligosaccharides211
         a.  CS Oligosaccharides211
         b.  Heparin/HS Oligosaccharides214
 D.  Conclusions214
 VII.OVERALL CONCLUSIONS215
 VIII.ABBREVIATIONS215
References216

Glycosylation is a common post-translational modification to cell surface and extracellular matrix (ECM) proteins as well as to lipids. As a result, cells carry a dense coat of carbohydrates on their surfaces that mediates a wide variety of cell–cell and cell–matrix interactions that are crucial to development and function. Because of the historical difficulties with the analysis of complex carbohydrate structures, a detailed understanding of their roles in biology has been slow to develop. Just as mass spectrometry has proven to be the core technology behind proteomics, it stands to play a similar role in the study of the functional implications of carbohydrate expression, known as glycomics. This review summarizes the state of knowledge for the mass spectrometric analysis of oligosaccharides with regard to neutral, sialylated, and sulfated compound classes. Mass spectrometric techniques for the ionization and fragmentation of oligosaccharides are discussed so as to give the reader the background to make informed decisions to solve structure-activity relations in glycomics. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 23:161–227, 2004.

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