Analysis of lipid A from Salmonella minnesota R595 lipopolysaccharide by chemical methods and nuclear magnetic resonance.

Modifications were introduced in established chemical methods in an attempt to develop reliable means of analysis of lipid A from Salmonella minnesota R595 lipopolysaccharide. Modified hydrolysis conditions led to an estimate of glucosamine content that was significantly higher than established values. This estimate is consistent with the amount of amide-linked fatty acid determined from kinetic studies of fatty acid release and with the presently accepted number of 3-deoxy-D-mannooctulosonic acid residues. Quantitative nuclear magnetic resonance spectroscopy was used to provide independent absolute estimates of the phosphorus-to-glucosamine ratio and of the level of total phosphate and fatty acids; these estimates were consistent with those obtained from chemical methods.