Lipopolysaccharide-free Escherichia coli OmpF and Pseudomonas aeruginosa protein P porins are functionally active in lipid bilayer membranes

Abstract

Escherichia coli porin OmpF and Pseudomonas aeruginosa porin protein P were eluted from sodium dodecyl sulfate-polyacrylamide gels. The resultant porin preparations were found to be devoid of detectable lipopolysaccharide (LPS) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining for LPS, direct enzyme-linked immunosorbent assays with LPS-specific monoclonal antibodies, and 2-keto-3-deoxyoctulosonic acid assays. The average conductances, ionic selectivities and incorporation rates of the electroeluted porins were identical to those of their conventionally purified counterparts. These data suggest that LPS is not required per se for porin function.