Dissociation and characterization of pilin isolated from Pseudomonas aeruginosa strains PAK and PAO.

Pili isolated from Pseudomonas aeruginosa strains PAK and PAO have been dissociated into subunits using the detergent octyl glucoside. Circular dichroism studies indicated that no change in protein conformation occurs as a result of this treatment. Ultracentrifugation measurements showed that both pilins have a Stokes radius of 21 A (1 A = 0.1 nm) corresponding to an axial ratio of between 3:1 and 5:1, when approximated as prolate or oblate ellipsoids. Sedimentation equilibrium measurements show that even at low protein concentrations the pilin-detergent complex exists as a mixture of monomers and dimers.