Fragmentation of N-linked glycans with a matrix-assisted laser desorption/ionization ion trap time-of-flight mass spectrometer.
N-Linked glycans were ionized from several matrices with a Shimadzu-Biotech AXIMA-QIT matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometer. [M+Na]+ ions were produced from all matrices and were accompanied by varying amounts of in-source fragmentation products. The least fragmentation was produced by 2,5-dihydroxybenzoic acid and the most by alpha-cyano-4-hydroxycinnamic acid and 6-aza-2-thiothymine. Sialic acid loss was extensive but could be prevented by formation of methyl esters. Fragmentation produced typical low-energy-type spectra dominated by ions formed by glycosidic cleavages. MS(n) spectra (n = 3 and 4) were used to probe the pathways leading to the major diagnostic ions. Thus, for example, an ion that was formed by loss of the core GlcNAc residues and the 3-antenna was confirmed as being formed by a B/Y rather than a C/Z mechanism. The proposed structures of several cross-ring cleavage ions were confirmed and it was shown that MS3 spectra could be obtained from as little as 10 fmol of glycan.
Harvey
David J
DJ
Oxford Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK. dh@glycob.ox.ac.uk
Martin
Rachel L
RL
Jackson
Kathryn A
KA
Sutton
Chris W
CW
D000818:Animals; D002240:Carbohydrate Sequence; D006023:Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry*; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013954:Thyroglobulin / Q000737:chemistry
D006023:Glycoproteins; D011134:Polysaccharides; D013954:Thyroglobulin