tripeptide

thumb|300px|A tripeptide (example Valine|Val-Gly-Ala) with green marked amino end (L-Valine) and blue marked carboxyl end (L-Alanine)

A tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds. As for proteins, the function of peptides is determined by the constituent amino acids and their sequence. In terms of scientific investigations, the dominant tripeptide is glutathione (γ-L-Glutamyl-L-cysteinylglycine), which serves many roles in many forms of life.