Pyroglutamic acid
-Pyroglutamic_acid_Structural_Formulae.png) | |
| Names | |
|---|---|
| Preferred IUPAC name
5-Oxoproline | |
| Systematic IUPAC name
5-Oxopyrrolidine-2-carboxylic acid | |
| Other names
Pidolic acid 5-Oxo-proline | |
| Identifiers | |
| 3DMet | B01549 |
| Abbreviations | Glp |
| 82134 | |
98-79-3 (2S)  4042-36-8 (2R) 149-87-1 | |
| ChEBI | CHEBI:16010  |
| ChEMBL | ChEMBL284718 |
| ChemSpider | 7127 (2S) 388752 (2R) 485 8710094 (2S)(3,4-3H2) |
| DrugBank | DB03088 |
| EC number | 205-748-3 |
| 1473408 | |
| |
| Jmol-3D images | Image |
| KEGG | C02237 |
| MeSH | Pyrrolidonecarboxylic+acid |
| PubChem | 7405 (2S) 439685 (2R) 499 10534703 (2S)(3,4-3H2) |
| RTECS number | TW3710000 |
| |
| UNII | SZB83O1W42 |
| Properties | |
| Molecular formula |
C5H7NO3 |
| Molar mass | 129.11 g·mol−1 |
| Melting point | 184 °C (363 °F; 457 K) |
| log P | -0.89 |
| Acidity (pKa) | -1.76, 3.48, 12.76 |
| Basicity (pKb) | 15.76, 10.52, 1.24 |
| Isoelectric point | 0.94 |
| Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
| verify (what is: /?) | |
| Infobox references | |
Pyroglutamic acid (also known as PCA, 5-oxoproline, pidolic acid, or pyroglutamate for its basic form) is an uncommon amino acid derivative in which the free amino group of glutamic acid or glutamine cyclizes to form a lactam. It is a metabolite in the glutathione cycle that is converted to glutamate by 5-oxoprolinase. Pyroglutamate is found in many proteins including bacteriorhodopsin. N-terminal glutamic acid and glutamine residues can spontaneously cyclize to become pyroglutamate. This is one of several forms of blocked N-terminals which present a problem for N-terminal sequencing using Edman chemistry, which requires a free primary amino group not present in pyroglutamic acid. The enzyme pyroglutamate aminopeptidase can restore a free N-terminus by cleaving off the pyroglutamate residue.[1]
Pyroglutamic acid, also known as pidolic acid, exists as two distinct enantiomers:
- (2R) or D which happens to be (+) or d
- (2S) or L which happens to be (–) or l
Uses
The sodium salt of pyroglutamic acid – known either as sodium pyroglutamate, sodium PCA, or sodium pidolate – is used on the skin to retain moisture.
L-pyroglutamic acid is sold as a dietary supplement.
Magnesium pidolate, the magnesium salt of pyroglutamic acid, is a mineral supplement.
References
- ↑ Podell, David N.; Abraham, George N. (1978), "A technique for the removal of pyroglutamic acid from the amino terminus of proteins using calf liver pyroglutamate amino peptidase", Biochem. Biophys. Res. Commun. 81 (1): 176–85, doi:10.1016/0006-291X(78)91646-7, PMID 26343.
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