Specificity and evolutionary divergence of the antigenic structure of the polypeptide chain elongation factors.

Antisera have been prepared against two electrophoretically homogeneous "polypeptide chain elongation factors," T and G, from Escherichia coli. Inactivation and precipitation tests showed that these two fractions were antigenically distinct with no cross-reaction. The immune inactivation curve of G factor from E. coli was distinguishable from that of G factor from Pseudomonas fluorescens. Mammalian factors were not inhibited by antibody directed against the E. coli T and G factors. By Ouchterlony diffusion tests, the antisera also detected significant antigenic variability among different bacterial species. It is concluded that the factors have undergone considerable evolutionary divergence in their antigenic structure.