Immunochemical characterization of major outer membrane components from Salmonella typhimurium

We used crossed immunoelectrophoresis to study detergent-solubilized components of the outer membrane of Salmonella typhimurium under nondenaturing conditions. The antisera used were raised against nondenatured outer membrane preparations. Lipopolysaccharide and lipoprotein were identified easily as discrete precipitates when they were solubilized with Triton X-100. However, solubilization of the porins with Triton X-100 resulted in a complex precipitate pattern, indicating incomplete dissociation of protein-protein interactions. A clear-cut pattern was obtained when the porins were first solubilized and denatured with hot sodium dodecyl sulfate, followed by removal of the sodium dodecyl sulfate and renaturation in the presence of Triton X-100. Our findings suggested that crossed immunoelectrophoresis can be used to study the antigenicity of nondenatured porins and the antibody responses to them.