Multi-dimensional NMR structural analyses of purified Lipid X and Lipid A (endotoxin)

The NMR structural analyses of unmodified, intact Lipid X and Lipid A (endo toxin) purified from wildtype Escherichia coli K-12 are described. Selectiv e inverse decoupling difference spectroscopy (SIDDS) is introduced as a sim ple and practical method for establishing phosphate linkage sites in Lipid A and related compounds. Homo- and heteronuclear multi-dimensional correlat ion NMR methods (COSY, TOCSY, HMQC, HMBC) were used in tandem to determine acyl and phosphate attachment sites and to derive detailed H-1,C-13 and P-3 1 NMR assignments. The NOESY results confirm the beta-glycosidic linkage an d chair conformations of the glucosamine rings in E. coli Lipid A. Copyrigh t (C) 1999 John Wiley & Sons, Ltd.