Location of the O-methyl groups in the O polysaccharide of Pseudomonas syringae pv. phaseolicola

Abstract The O-methylation pattern of the O polysaccharide (OPS) of the lipopolysaccharide of Pseudomonas syringae pv. phaseolicola GSPB 1552 was revealed by methylation (CD 3 I) analysis, Smith degradation, and NMR spectroscopy. Together with the major O repeats consisting of d -rhamnopyranose ( d -Rha p ) and d -fucofuranose ( d -Fuc f ), there are minor repeats (∼30%) containing 3- O -methyl- d -rhamnose ( d -acofriose), which is 2-substituted in the interior repeats and occupies the terminal non-reducing end of the OPS. It was suggested that the methylated O repeats are linked to each other nearby the non-reducing end of the OPS and that the ‘biological’ O repeat of the OPS has the following structure: Download full-size image