β-Elimination of glucosyluronic residues during methylation of an acidic polysaccharide from Erwinia chrysanthemi CU 643 Original Research Article

The Erwinia chrysanthemi CU643 EPS has a linear hexasaccharide repeating unit in which a 4-linked uronic acid residue is present. The EPS was methylated by either the NaOH–Me2SO–MeI or Li-dimsyl procedure. MALDI-TOF MS analysis of the methylated products indicates that the β-eliminative degradation occurs during the methylation, as characterized by serial fragments of the hexasaccharide repeating units. The degradation was clearly defined from the methylation of a glucosyluronic-containing pyruvated pentasaccharide.