Use of 13C-n.m.r. spectroscopy for the quantitative estimation of 3-O- and 3,6-di-O-substituted d-glucopyranosyl residues in α-d-glucans formed by the d-glucosyltransferases of Streptococcus sobrinus

摘要: Abstract The 13 C-n.m.r. spectra of the three α- d -glucans from Streptococcus sobrinus and dextran Leuconostoc mesenteroides , which differ widely in ratios ω (terminal, nonreducing) -glucopyranosyl groups: 3-:6-:3,6-linked (Glc) residues, were measured 0.5 m NaOH at 22°. C-1 signals 3- O -substituted Glc a linear sequence, 6- 3,6-di- (1→6)-linked attached to O-3 distinguished each other. C-3 signal 3,6-linked appeared downfield by 0.6 1.0 p.p.m. compared 3-linked sequence. C-6 ω-terminal, 3-linked, 6-linked, also assigned. C-2 sequence separately, 73.76 Based on these assignments, various residues S. quantitatively estimated areas atom Glc, 6-linked ω-Glc groups residues. figures thus derived for linkage close those obtained methylation analysis.