The structure of the capsular polysaccharide (CPS) of serotype Ia group B Streptococcus (GBS) has been characterized for years, but its repeating unit, which is a challenging pentasaccharide with a branch and a difficult α-sialic acid linkage, has not been synthesized yet. In this report, an effective synthesis was developed for the serotype Ia GBS CPS repeating unit, which had a reactive functionality linked to its main-chain reducing end to enable further elaboration, such as coupling with carrier proteins. The target molecule was accomplished by a convergent [2 + 3] glycosylation strategy employing a sialo-disaccharide as donor and a branched trisaccharide as acceptor. The strategy was designed to suit the synthesis of oligomers of the repeating unit.
capsular polysaccharide, glycosylation, Streptococcus agalactiae
NCBI PubMed ID: 25674920Publication DOI: 10.1021/ol5036563Journal NLM ID: 100890393Publisher: American Chemical Society
Correspondence: zwguo@chem.wayne.edu
Institutions: Department of Chemistry, Wayne State University , 5101 Cass Avenue, Detroit, Michigan 48202, United States
Methods: 13C NMR, 1H NMR, NMR-2D, TLC, chemical synthesis, chemical methods, MALDI-TOF MS, NMR-1D, glycosylation