Dipeptide

A dipeptide is a sometimes ambiguous designation of two classes of organic compounds: Its molecules contain either two amino acids joined by a single peptide bond or one amino acid with two peptide bonds.

Two amino acids, one peptide bond

In this usage, X dipeptide (with X designating an amino acid) must be understood as di-X peptide. This nomenclature is continued by tripeptide (three amino acids, two peptide bonds), tetrapeptide, and so on; longer chains are called oligopeptide, polypeptide, protein.

Glycylglycine

Dipeptides are produced from polypeptides by the action of the hydrolase enzyme dipeptidyl peptidase.^[1] Dietary proteins are digested to dipeptides and amino acids, and the dipeptides are absorbed more rapidly than the amino acids, because their uptake involves a separate mechanism. Dipeptides activate G-cells found in the stomach to secrete gastrin.

The Bergmann azlactone peptide synthesis is a classic organic synthesis for the preparation of dipeptides.^[2]

Examples

all types of Dipeptide list

• Carnosine (beta-alanyl-L-histidine) is highly concentrated in muscle and brain tissues.
• Anserine (beta-alanyl-N-methyl histidine) is found in the skeletal muscle and brain of mammals.
• Homoanserine (N-(4-aminobutyryl)-L-histidine) is another dipeptide identified in the brain and muscles of mammals.
• Kyotorphin (L-tyrosyl-L-arginine) is a neuroactive dipeptide which plays a role in pain regulation in the brain.
• Balenine (or ophidine) (beta-alanyl-N tau-methyl histidine) has been identified in the muscles of several species of mammal (including man), and the chicken.
• Aspartame (N-L-α-aspartyl-L-phenylalanine 1-methyl ester) is an artificial sweetener.
• Glorin (N-propionyl-γ-L-glutamyl-L-ornithine-δ-lac ethyl ester) is a chemotactic dipeptide for the slime-mould Polysphondylium violaceum.
• Barettin (cyclo-[(6-bromo-8-en-tryptophan)-arginine]) is a cyclic dipeptide from the marine sponge Geodia barretti.
• Pseudoproline
• Glycylglycine

One amino acid, two peptide bond

In this usage, X dipeptide is taken literally: One amino acid X is equipped with two minimal peptide bonds: The C terminus COOH becomes COCH₃, the N terminus NH₂ becomes NHCH₃. For instance, alanine dipeptide is CH₃CONHCH(CH₃)CONHCH₃.^[3]

References

1. Steane, Richard. "Hydrolysis of a dipeptide". BioTopics. Retrieved 28 July 2014.
2. Bergmann, M. et al., Ann. 449, 277 (1926); "Bergmann Azlactone Peptide Synthesis"
3. Head-Gordon, Teresa; Head-Gordon, Martin; Frisch, Michael J.; Brooks, Charles; Pople, John (2009). "A theoretical study of alanine dipeptide and analogs". International Journal of Quantum Chemistry 36: 311. doi:10.1002/qua.560360725.

External links

• An introduction to dipeptides at PeptideGuide.