Studies on the chemical basis of the antigenicity of proteins. 5. Synthesis, characterization and immunogenicity of some multichain and linear polypeptides containing tyrosine

Abstract

A series of 29 linear and multichain copolypeptides, containing all or some of the amino acids tyrosine, glutamic acid, alanine and lysine, were synthesized and characterized. Many of the above-mentioned polymers were tested for their immunogenicity in rabbits. It was found that 15 of the synthetic polypeptides investigated were immuno-genic, eliciting between 100 and 2000 [mu]g of precipitable antibody/ml of serum. Tyrosine was present in all of the polymers found to be immunogenic. To elicit biosynthesis of antibody the immunogenically important area must readily be accessible, and cannot be hidden in the interior of the molecule. The overall shape of the molecule does not seem to be a critical factor in immunogenicity. The smallest synthetic polypeptide antigen among the substances investigated was a linear polymer of an average molecular weight around 4000. From the molar ratios of antibody to antigen in the equivalence zone it may be concluded that the number of antigenic specific sites on the molecule decreases with the molecular weight of the synthetic antigen.