Identification and structural analysis of synthetic oligosaccharides of Shigella sonnei using MALDI-TOF MS

MALDI-TOF mass spectroscopy was used for the molecular weight determination of protected synthetic oligosaccharides related to a cell surface bacteria l polysaccharide. By-products containing chlorinated protecting groups caus ed isotopic patterns characteristic of the natural isotopic distribution of chlorine, were identified on the basis of isotopic distribution. 2,4,6-Tri hydroxyacetophenone (THAP) as a matrix was better than 2,5-dihydroxybenzoic acid (DHB) for compounds containing chlorine, since monoisotopic resolutio n and no fragmentation were observed. In the post source decay (PSD) mode t he identification of the oligosaccharide sequence through cleavage of the i nterglycosidic linkages was also possible, thus providing a sensitive and a ccurate tool for the structural verification of synthetic oligosaccharide i ntermediates. (C) 2001 Elsevier Science Ltd. All rights reserved.