Journal of Nutrition & Food Sciences
Open Access

Peptides

Peptides are short chains of between two and fifty amino acids, linked by peptide bonds. Chains of less than ten or fifteen amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.

A polypeptide is a longer, continuous, and unbranched peptide chain of up to approximately fifty amino acids. Hence, peptides fall under the broad chemical classes of biological oligomers and polymers, alongside nucleic acids, oligosaccharides, polysaccharides, and others.

When a polypeptide contains more than approximately fifty amino acids it is known as a protein. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, or to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies.

Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (carboxyl group) residue at the end of the peptide