Lipopolysaccharides (LPS) from antigenically different strains assigned to serogroups 0: 3 and 0: 6 of Helicobacter pylori were isolated as water-soluble material of high M , and as water-insoluble gels of low M I . Chemical and spectroscopic analyses of the soluble LPS and oligosaccharides liberated from the water-insoluble gels led to proposed structures with Lewis (Le) antigen determinants terminating regular repeating units of different types, linked in turn to inner core regions of invariable structure. The 0 : 6 LPS has two populations of related molecules with chains of 3-linked D-glycero-a-D-manno-heptose residues similar to those in the M019 strain, one with and the other without a single terminal Lewis (Ley) epitope. In contrast, in the 0 : 3 LPS, Lewis (Le" and Ley) epitopes terminate a partially fucosylated Nacetyllactosaminoglycan, but a heptan chain similar to that in the 0 : 6 LPS was shown to connect the outer chains to the inner core. These LPS provide examples of the molecular mimicry of cell-surface glycoconjugates. Structural variations of LPS between strains, and differences in some aspects of structure within strains, between high Mt and low M , LPS indicate a class of LPS whose mechanisms of biosynthesis lead to overall architectures different from those characteristic of most LPS from enteric bacteria.Keywords: Helicobacter pylori; core oligosaccharide ; lipopolysaccharide ; 0 antigen ; molecular mimicry. Lipopolysaccharides (LPS) comprise an important group of bacterial cell-surface carbohydrate components, which often interact specifically with surface components of an infected host. Helicobacter pylori has been implicated as a causative agent of gastritis, gastric and duodenal ulcers, and gastric carcinoma [I]. Until recently the chemical structure of LPS was largely undefined, although LPS is known to have low endotoxic activity, induces a low immunological response, and has been implicated in a variety of biological interactions. These include an inhibitory effect on mucus glycosylation, interference with mucosal integrity, the stimulation of pepsinogen secretion, and a role in mediating adherence of the bacterium laminin in the basement membrane (2, 31. These effects, however, were noted without regard to possible structural differences in LPS. Evidence that such differences occur has been indicated by the differentiation between H. pylovi strains in electrophoretic patterns in SDS/ PAGE coupled with antigenic analyses with strain-specific antisera [41. In experiments of a different type [S], differences were reported in the binding of strains of H. pylori to human gastric mucosal cells containing the Lewish (Leh) antigen. The binding of one such strain, P 466, froin a patient with dyspeptic syndrome 163, to gastric mucosa was inhibited by the Leh antigen, whereas the M019 strain, from an asymptomatic patient, did not bind to the mucosa. Although LPS was not implicated in the interaction or lack of interaction of these H. pylori strains with gastric mucosa, these observations [5, 61...

The complete structure for the core oligosaccharide region of the water-insoluble low-M(r) lipopolysaccharide of Campylobacter jejuni serotype O:3 from phenol/water extraction of bacterial cells was assigned through studies on derivatives of the liberated oligosaccharide. Structure determinations were performed using 1H-NMR and 31P-NMR spectroscopies, methylation analysis supported by fast-atom-bombardment mass spectrometry, and Smith degradation experiments. It was concluded that the complete chains in the core oligosaccharide had the following structure in which a proportion of the terminal residues were phosphorylated: [formula: see text] From a similar series of experiments, it was concluded that an associated polysaccharide, which was isolated from the water phase of the phenol/water extracts, had the following repeating unit in which a proportion of the previously unknown L-glycero-D-ido-heptose (L-alpha-D-ido-Hep) residues were present as 3-hydroxypropanoyl esters, and were not covalently linked to the lipopolysaccharide: [formula see: text]

The complete structure for the core oligosaccharide region of the water-insoluble low-M(r) lipopolysaccharide of Campylobacter jejuni serotype O:3 from phenol/water extraction of bacterial cells was assigned through studies on derivatives of the liberated oligosaccharide. Structure determinations were performed using 1H-NMR and 31P-NMR spectroscopies, methylation analysis supported by fast-atom-bombardment mass spectrometry, and Smith degradation experiments. It was concluded that the complete chains in the core oligosaccharide had the following structure in which a proportion of the terminal residues were phosphorylated: [formula: see text] From a similar series of experiments, it was concluded that an associated polysaccharide, which was isolated from the water phase of the phenol/water extracts, had the following repeating unit in which a proportion of the previously unknown L-glycero-D-ido-heptose (L-alpha-D-ido-Hep) residues were present as 3-hydroxypropanoyl esters, and were not covalently linked to the lipopolysaccharide: [formula see: text]

A range of new functional copolymers bearing aldehyde and carboxylic acid groups have been prepared by functionalization of poly(4-methylstyrene). These polymers have molecular weights from 2,000 to 16,500 and contain up to 20% aldehyde and up to 90% carboxylic acid groups. The reaction proceeds by selective catalytic oxidations with molecular oxygen or air in acetic acid/organic cosolvent mixtures in presence of cobalt acetate and sodium bromide or hydrogen bromide. The effects of reaction temperature, catalyst, co-solvents and oxygen partial pressure on the reaction are described. 0 1995 John Wiley & Sons, Inc.