Rhodopseudomonas palustris Strain CGA009 Produces an O-Antigen Built up by a C-4-Branched Monosaccharide: Structural and Conformational Studies.

Here, the analysis of the peculiar homopolymeric O-chain, isolated from the lipopolysaccharide (LPS) of Rhodopseudomonas palustris strain CGA009, is reported. The O-chain is built up of a novel 4-C-branched sugar (12-deoxy-4- C-(d- altro-5,7,8,9-tetrahydroxyhexyl))-3- O-methyl-d-galactopyranose)) whose structure, absolute configuration, and conformational features were deduced by 2D NMR spectroscopy, optical rotation measurements, and molecular dynamics simulations.