Chemical properties of the pili of Corynebacterium renale

Pili separated from the cells of Corynebacterium renale strain 46 (type II) by agitation at high speed in a homogenizer were purified by repeated cycles of ammonium sulfate precipitation, sonic treatment, and centrifugation. The preparation of purified pili formed a single antigen-antibody line in agar gel and showed an absorption maximum at 275 nm. The pili subjected to dodecyl sulfate-polyacrylamide gel electrophoresis formed a main band and corresponded to the molecular weight of 19,000. The fact that the total nitrogen of the amino acids of the pili was nearly equal to its nitrogen content, together with the absence of detectable carbohydrate, has led to the conclusion that the pili are protein. The pilial protein was composed of 20 amino acids. Preparations of pili which had been treated with 0.5 n NaOH, but not with 1 n HCl, no longer appeared filamentous and failed to form a precipitate with the antibody in agar gels. A comparison has been made of the amino acid composition and certain properties of the pili of C. renale and type I pili and F pili of gram-negative bacteria.