Molecular dynamics simulations of six different fully hydrated monomeric conformers of Escherichia coli re-lipopolysaccharide in the presence and absence of Ca2+.

Six previously published conformational models of Escherichia coli Re lipopolysaccharide (ReLPS) were subjected to molecular dynamics simulations using the CHARMM force field. The monomers of ReLPS were completely immersed in a water box. The dynamic behavior of the solvated models in the presence and absence of calcium cations was compared.

Comparison of X-ray powder-diffraction data of various bacterial lipopolysaccharide structures with theoretical model conformations.

X-ray powder-diffraction experiments have been performed on dry samples of lipid A and various rough-mutant lipopolysaccharides (LPS) of Salmonella minnesota, Salmonella typhimurium and Escherichia coli. The diffraction patterns obtained indicated exclusively lamellar, bilayered arrangements in all samples. The periodicities were found to be in the range 4.

Effect of pH on solubility and ionic state of lipopolysaccharide obtained from the deep rough mutant of Escherichia coli.

The dissociation of the highly aggregated form of lipopolysaccharide (LPS) from Gram-negative bacteria to the monomeric (or soluble) form is though to be the initial step in the activation of responding cells (macrophages, B-cells, neutrophils, monocytes, and endothelial cells) by LPS. This process is presently not adequately understood. Using the equilibrium dialysis apparatus and a highly purified and well-characterized radiolabeled deep rough chemotype LPS ([14C]ReLPS) from Escherichia coli D31m4, we have examined the effect of pH on its solubility (CT) and ionic states in aqueous media.

Molecular modelling of the three-dimensional structure and conformational flexibility of bacterial lipopolysaccharide.

Molecular modelling techniques have been applied to calculate the three-dimensional architecture and the conformational flexibility of a complete bacterial S-form lipopolysaccharide (LPS) consisting of a hexaacyl lipid A identical to Escherichia coli lipid A, a complete Salmonella typhimurium core oligosaccharide portion, and four repeating units of the Salmonella serogroup B O-specific chain. X-ray powder diffraction experiments on dried samples of LPS were carried out to obtain information on the dimensions of the various LPS partial structures. Up to the Ra-LPS structure, the calculated model dimensions were in good agreement with experimental data and were 2.