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.
Contents
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.
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
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- An introduction to dipeptides at PeptideGuide.
