NMR structural analysis of the capsular polysaccharide from Streptococcuspneumoniae serotype 6C

The original structure of Streptococcuspneumoniae capsular polysaccharide (CPS) serotype 6C was proposed based on chemical degradation and tandem mass analysis [J. Clin. Microbiol.2007, 45, 1225–1233]. In order to confirm the repeat unit structure and assign the stereochemical structure, the CPS 6C and the known CPS 6A were fully characterized by NMR spectroscopy. Full 1H and 13C NMR spectra assignments of CPS 6C and CPS 6A were achieved based on DQCOSY, TOCSY, HSQC, HMBC, and NOESY analysis. These analyses confirmed the published structure of CPS 6A and established the repeat unit structure of the CPS 6C as:→2)-α-d-Glcp-(1→3)-α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Ribitol-(5→phosphate-.

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► The repeat unit structure of serotype 6C is established by various NMR spectra study.
► 2D-NMR studies led to full 1H and 13C NMR spectra assignments of CPS 6C and CPS 6A.
► 2D-NMR studies confirmed the published structure of CPS 6A and established the repeat unit structure of the CPS 6C.