Beschreibung:
<jats:p>The great majority of trimeric porins of Gram‐negative bacteria cannot be dissociated into monomers without disrupting their folded conformation. The porin of <jats:italic>Campylobacter jejuni</jats:italic>, however, displays two folded structures, a classical oligomer and a monomer resistant to detergent denaturation. We probed the transition of trimer to monomer using light scattering experiments and examined the secondary structures of these two molecular states by infra‐red spectroscopy. The channel‐forming properties of both trimer and monomer were studied after incorporation into artificial lipid bilayers. In these conditions, the trimer induced ion channels with a conductance value of 1200 pS in 1 M NaCl. The pores showed marked cationic selectivity and sensitivity to low voltage. Analysis of the isolated monomer showed nearly the same single‐channel conductance and the same selectivity and sensitivity to voltage. These results indicate that the folded monomer form of <jats:italic>C. jejuni</jats:italic> MOMP displays essentially the same pore‐forming properties as the native trimer.</jats:p>