Protein antigenic sites

These, and other, mechanisms possibly involved in erythrophagocytosis will have to be elucidated in the future. Also shoidd be investigated the matter of whether antigenic sites (proteins or lipids), other than the desialylated glycoproteins and glycolipids having penulti-... 

Figure 2 Immobilized antigen ELISA format. Antigen is immobilized to a solid phase by passive adsorption. Following removal of unbound antigen, analyte (free H) and antigen (H-protein) compete for a fixed number of primary antibody (Y) binding sites. Unbound materials are removed (dotted line). Secondary antibody-enzyme conjugate (Y-E) is added to bind to primary antibody followed by another wash step. Substrate (A) for the enzyme is added to detect the bound enzyme. The amount of colored product ( ) detected is inversely proportional to the amount of analyte present...

Antigens usually are macromolecules that contain distinct antigenic sites or epitopes , which can be recognized and interact with the various components of the immune system. They can exist as individual molecules composed of synthetic organic chemicals, proteins, lipoproteins, glycoproteins, RNA, DNA, polysaccharides—or they may be parts of cellular structures (bacteria or fungi) or viruses (Male et al., 1987 Harlow and Lane, 1988). 

Bendayan, M. (1989) Ultrastructural localization of insulin and C-peptide antigenic sites in rat pancreatic B cell obtained by applying the quantitative high-resolution protein A-gold approach. Am. J. Anat. 185, 205-216. 

Bendayan M, Zollinger M. Ultrastractural localization of antigenic sites on osmium-fixed tissues applying the protein A-gold technique. J Histochem Cytochem 1983 31 101-109. 

Tyramide signal amplification This procedure, designated as a catalyzed reporter deposition (CARD) or tyramide signal amplification (TSA), takes advantage of horseradish peroxidase (HRP) from an HRP-labeled secondary antibody to catalyze in the presence of hydrogen peroxide the oxidation of the phenol moiety of labeled tyramine. On oxidation by HRP, activated tyramine molecules rapidly bind covalently to electron-rich amino acids of proteins immediately surrounding the site of the immunoreaction. This allows an increase in the detection of an antigenic site up to 100-fold compared with the conventional indirect method with no loss in resolution. 

ATASSl Protein Antigenic Sites and Free Synthetic Peptides... 

This article focuses mainly on the Immunology of proteins whose complete antigenic structures have been chemically localized and synthetically confirmed. These are Mb, lysozyme, Hb and serum albumin. The antigenic sites of many other proteins are now being Investigated. 

It should be noted that the above strategy, although first employed In the delineation of protein antigenic sites. Is applicable, with appropriate adaptations, to the precise delineation and chemical synthesis of other types of protein binding sites. The Introduction of the concept of surface-simulation synthesis ( 4, ) has provided a methodology by which In principle any type of protein binding site can be mimicked synthetically after careful chemical characterization. 

Figure 1. A schematic diagram showing the mode of folding of Mb and Its antigenic structure. The solid black portions represent segments which have been shown to comprise accurately the antigenic sites of the protein. The striped parts, each corresponding to one amino acid residue only, can be part of the antigenic sites with some antisera. The dotted portions represent parts of the molecule which have been shown exhaustively to reside outside antigenic sites (1).

---