Dipeptides

organic substances consisting of two amino acids connected by a peptide bond (—CO—NH—). Optically active, they form crystals of characteristic shape. The isoelectric point, color reactions, and other properties of dipeptides are determined by the amino acids that enter into their composition. Dipeptides are compounds intermediate between polypeptides and amino acids and are formed by the hydrolysis of proteins. Dipeptides consisting of the same L-amino acids but in different order yield isomers, for example, leucyl-alanine and alanyl-leucine. Natural dipeptides, such as carnosine and anserine, are found in animal tissues. A dipeptide molecule can be hydrolyzed by acids, alkalies, or enzymes (dipeptidases) to yield two amino acids.