Studies on synthetic polypeptide antigens. XVII. Immunochemical properties of synthetic polypeptide-antibody systems.

The synthetic polypeptide—antibody precipitin curves indicate the presence of multiple antigenic systems in the polypeptides: a typical precipitin curve can be analysed into a minimum of four discrete antigen—antibody systems. Prolonging the course of immunization brings out the weaker antigenic systems and accounts for the observed broadening of the precipitin curve. Longer periods of incubation of the antigen—antibody reaction (20 days) also enhance the precipitation of the weaker antigenic systems. Dilution of the antibody results in a non-linear change in precipitable antibody concentration. Increase in the viscosity of the reaction medium with sucrose up to approximately 5 cp at 4° has little effect on the precipitin reaction.