Fig. 3.

Structural determination of the two O1 OPS glycoforms. (A) Shows the final structures of the O1b (Upper) and O1a (Lower) glycans obtained from mild acid degradation of K. pneumoniae NCTC11682 LPS. The O2a and O1 glycan repeat units are boxed. The substitution of the outer core Kdo residue with Hep is nonstoichiometric. The sugar residue labeling follows assignments given in an earlier study of K. pneumoniae OPS terminal modifications (32). (B) Shows parts of ¹H,¹³C HSQC (Top) and HMBC (Bottom) spectra of the OPS. The corresponding parts of ¹H and ¹³C NMR spectra are shown along the horizontal and vertical axes, respectively. Correlations belonging to terminal β-Galp3,4(S-Pyr) (residue T) are marked with green. Attachment of S-Pyr at position O-3 and O-4 of T was confirmed by HMBC correlation between ketal carbon of Pyr and T H-3 at δ 109.1/4.22. NMR was performed once.