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 M r 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.