Peptides are short chains of amino acids linked by covalent chemical bonds. Covalent bonds are formed by the linkage between the carboxyl group of one amino acid and the amino group of another. Although recent advances in peptide technology have made it possible to synthesize peptides over 150 amino acids long, peptides have typically been distinguished from proteins based on their size. Biological peptides contain approximately up to 50 amino acids.
Blocking peptides are peptides that bind specifically to the target antibody and block antibody binding. This is because the peptide resembles the epitope recognized by the antibody. Antibodies bound to the blocking peptide no longer bind to the epitope in the protein. Whatever bands that show up would then be due to non-specific binding. This mechanism is useful when non-specific binding is an issue, for example, in Western blotting (immunoblot) and immunohistochemistry (IHC)
