Analytical studies of lipopolysaccharide and its derivatives from Salmonella minnesota R595. II. Proton and carbon magnetic resonance spectra

¹H and ¹³C nuclear magnetic resonance spectroscopy are of limited value for study of native lipopolysaccharide from Salmonella minnesota R595. Methylation and acetylation of derived lipid A gave preparations with better solubility properties in a number of solvents, but sharpest spectra were obtained with lipopolysaccharide which had been treated with hydrazine to remove ester-linked fatty acids. ¹³C-NMR of lipid A indicates that hydroxy fatty acid is present as 3-hydroxyacyl amide, 3-acyloxy amide and 3-acyloxy ester. All normal fatty acids appear to be present as substituents on the hydroxyacyl residues. These conclusions are consistent with kinetics of release of fatty acids and component estimates using improved procedures.