Improved MALDI-Matrix for Glycoconjugates

Motivation

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has become a standard method in the field of proteomics by combining fast and reproducible measurements with high mass accuracy. Peptides can be analyzed with high confidence, using standard MALDI-matrices like 2,5-dihydroxybenzoic acid (DHB), and α-cyano-4-hydroxycinnamic acid (CHCA). An upcoming field of application for MALDI-TOF-MS is the analysis of glycoconjugates, like glycans and glycopeptides. Compared to peptides, those glycoconjugates have different requirements on the MALDI-matrix that is used. Here the development of new MALDI-matrices can greatly improve the detection and quantification of glycans and glycopeptides.

MALDI-TOF-MS spectra of tryptic IgG Fc N-glycopeptides co-crystallized with DHB (Figure A) or Cl-CCA (Figure B) and measured in reflectron-negative ion mode. Profiling of IgG Fc N-glycopeptides was performed after 96-well format cellulose-HILIC purification. Dashed arrows, IgG2 glycopeptides; solid arrows, IgG1 glycopeptides; blue square, N-acetylglucosamine; red triangle, fucose; green circle, mannose; yellow circle, galactose; purple diamond, N-acetylneuraminic acid. *, in-source fragment.

© MPI Magdeburg (BPE)

MALDI-TOF-MS spectra of tryptic IgG Fc N-glycopeptides co-crystallized with DHB (Figure A) or Cl-CCA (Figure B) and measured in reflectron-negative ion mode. Profiling of IgG Fc N-glycopeptides was performed after 96-well format cellulose-HILIC purification. Dashed arrows, IgG2 glycopeptides; solid arrows, IgG1 glycopeptides; blue square, N-acetylglucosamine; red triangle, fucose; green circle, mannose; yellow circle, galactose; purple diamond, N-acetylneuraminic acid. *, in-source fragment.

© MPI Magdeburg (BPE)

Aim of the Project

For MALDI analysis of glycans and glycopeptides the choice of matrix is crucial in minimizing desialylation by mass spectrometric in-source and metastable decay. Here we evaluated the potential of 4-chloro-α-cyanocinnamic acid (Cl-CCA) for MALDI-TOF-MS analysis of labile sialylated tryptic N-glycopeptides and released N- and O-glycans. Similar to 2,5-dihydroxybenzoic acid (DHB), but in contrast to α-cyano-4-hydroxycinnamic acid (CHCA), the Cl-CCA matrix allowed the analysis of sialylated N-glycans, O-glycans and glycopeptides in negative ion mode MALDI-TOF-MS, which clearly demonstrates the potential of this rationally designed matrix.

References

Selman, M. H. J.; Hoffmann, M.; Zauner, G.; McDonnell, L. A.; Balog, C. I. A.; Rapp, E.; Deelder, A. M.; Wuhrer, M.: MALDI-TOF-MS analysis of sialylated glycans and glycopeptides using 4-chloro-α-cyanocinnamic acid matrix. Proteomics 12 (9), pp. 1337 - 1348 (2012)

MPG.PuRe

DOI