Interactions between lipopolysaccharide and outer membrane proteins of Acinetobacter calcoaceticus studied by an affinity electrophoresis system.

R-Form lipopolysaccharides of Acinetobacter calcoaceticus could be incorporated into polyacrylamide gels in an immobile form by adding it directly to the acrylamide-N,N'-methylenebisacrylamide polymerization mixture. The separation of A. calcoaceticus 69 V outer membrane proteins in these affinity gels demonstrated a specific interaction with the lipopolysaccharide ligand for one of the proteins. This protein is heat-modifiable and has an Mr of about 18,000. By incorporation of varying concentrations of lipopolysaccharide, a dissociation constant of the protein-lipopolysaccharide complex of 0.5 mM could be determined. In comparison, for another A. calcoaceticus strain, CCM 5593, a higher dissociation constant (1.0 mM)--indicative of lower affinity--was obtained.