tripeptide

A tripeptide is an oligopeptide consisting of three amino acids linked by two peptide bonds. It has an N-terminal amino group and a C-terminal carboxyl group, and its amino acid sequence is read from the N to the C terminus. The side chains influence its properties, such as charge and hydrophobicity.

Tripeptides are formed by condensation reactions, either during ribosomal synthesis of proteins (as successive amino acids are added) or by chemical synthesis and proteolysis of larger proteins. If all residues are L-amino acids, the molecule typically appears in a single chiral arrangement; incorporation of D-amino acids creates diastereomers.

Examples include glutathione, a tripeptide of glutamate, cysteine, and glycine (gamma-glutamylcysteinylglycine) that functions as an antioxidant. Tripeptides can occur as components of proteins or exist as free molecules used in research, diagnostics, and industry.

In research and industry, tripeptides serve as substrates for proteases, building blocks in peptide libraries, or starting points for synthesis. They have molecular weights around 300 Da and can be produced by solid-phase peptide synthesis or enzymatic methods.