Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. A peptide is formed by joining two or more amino acids. When the number of amino acids is less than about 50 these molecules are named peptides while larger sequences are referred to as proteins. The amino acids are coupled by a peptide bond, a special linkage in which the nitrogen atom of one amino acid binds to the carboxyl carbon atom of another.
Peptides are present in every living cell and possess a variety of biochemical activities. They appear as enzymes, hormones, antibiotics, receptors, etc. peptide synthesis is done by coupling the carboxyl group or C-terminus of one amino acid to the amino group or N-terminus of another.
Peptides play a crucial role in fundamental physiological and biochemical functions of life. For decades now, peptide research has been growing as a field in science. They have recently received prominence in molecular biology for several reasons. The first is that they allow the creation of antibodies in animals without the need to purify the protein of interest. This involves synthesizing antigenic peptides of sections of the Peptides Forum protein of interest; these are then used to make antibodies in a rabbit or mouse against the protein. Another reasons interest in peptides has grown recently is that they have become instrumental in mass spectrometry, allowing the identification of proteins of interest based on peptide masses and sequence; in this case they are most often generated by in-gel digestion after electrophoretic separation of the proteins.
Peptides have recently been used in the study of protein structure and function. For example, synthetic peptides can be used as probes to see where protein-peptide interactions occur. Inhibitory are also used in clinical research to examine the effects of they on the inhibition of cancer proteins and other diseases.
As interest in peptides has grown, so have techniques for manufacturing it and studying new applications for it. For example, the library is a newly developed technique for protein related study. A library contains a great number of they that have a systematic combination of amino acids; it provides a powerful tool for drug design, protein-protein interactions, and other biochemical as well as pharmaceutical applications.