tripeptidy

Tripeptides are molecules composed of three amino acids linked by two peptide bonds. They are the simplest peptides whose activity depends on a defined sequence of amino acids, making their properties highly dependent on the identity of each residue. All tripeptides have an N-terminus and a C-terminus, and their overall charge and solubility are determined by the side chains of the constituent amino acids.

The most well-known natural tripeptide is glutathione, whose sequence is glutamate-cysteinylglycine. Glutathione acts as a major cellular antioxidant and participates in detoxification reactions. Tripeptides also occur as intermediates or products in various biosynthetic pathways. In addition to natural examples, tripeptides can be produced synthetically via chemical peptide synthesis or enzymatic methods, and they can function as research probes or potential therapeutics.

Biosynthesis of low-molecular weight peptides like glutathione typically proceeds via two ATP-dependent steps: formation of the gamma-glutamylcysteinyl bond, followed by attachment of glycine. In the laboratory, tripeptides are commonly prepared using solid-phase peptide synthesis, employing protecting group strategies to assemble the chain from the C-terminus to the N-terminus. Hydrolysis by proteases breaks tripeptides down into individual amino acids.

Because of their small size and defined sequence, tripeptides are studied for roles in signaling, nutrition, antioxidant defense, and drug design. In industry, they appear in cosmetics and dietary supplements as antioxidants or bioactive fragments.