Amino Acid Substitution and the Antigenicity of Globular Proteins

Abstract

This chapter discusses the amino acids substitution and the antigenicity of globular proteins. It focuses on the role of sequential determinants, related to the amino acid sequence of peptides, and conformational determinants, the product of protein conformation not expressed in linear peptides. The experimental approaches employed to provide the amino acid substitutions are from the chemical modification of single residues, use of naturally occurring amino acid mutants, and use of a series of genetically homologous proteins of known sequence. It indicates that antibodies are best produced to regions of protein antigens that bear sequences different from those of homologous proteins of the immunized species. Also, globular proteins have highly immunogenic and relatively constant surface patches, the specificity of which is determined by their amino acid composition. The chapter discusses the importance of slight genetic changes in determining antigenic specificity. In certain crucial sites, a single amino acid difference resulting from one point mutation can alter conformation and determine complete specificity between two protein antigens.