Structure of a d-glycero-d-manno-heptan from the lipopolysaccharide of Helicobacter pylori

A lipopolysaccharide (LPS) was isolated by hot phenol–water extraction from Helicobacter pylori strain D4 and found to contain no fucosylated poly-N-acetyllactosamine chain typical of most H. pylori strains studied but a homopolymer of d-glycero-d-manno-heptose (dd-Hep). The heptan attached to a core oligosaccharide was released by mild acid degradation of the LPS, and the following structure of the trisaccharide-repeating unit was established by chemical methods and 1H and 13C NMR spectroscopy:→2)-d-α-d-Hepp-(1→3)-d-α-d-Hepp-(1→3)-d-α-d-Hepp-(1→1H NMR spectroscopy performed on small amounts of the intact LPS revealed the presence of the same polysaccharide in LPS of H. pylori strains D2 and D5, but not strain D10.