From Wikipedia, the free encyclopedia
Pyroglutamic acid Names Preferred IUPAC name5-Oxoproline
Systematic IUPAC name5-Oxopyrrolidine-2-carboxylic acid
Other names3D model (
JSmol)
Abbreviations Glp Beilstein Reference 82134 ChEBIInChI=1S/C5H7NO3/c7-4-2-1-3(6-4)5(8)9/h3H,1-2H2,(H,6,7)(H,8,9)
NKey: ODHCTXKNWHHXJC-UHFFFAOYSA-N
NInChI=1S/C5H7NO3/c7-4-2-1-3(6-4)5(8)9/h3H,1-2H2,(H,6,7)(H,8,9)/t3-/m0/s1
InChI=1S/C5H7NO3/c7-4-2-1-3(6-4)5(8)9/h3H,1-2H2,(H,6,7)(H,8,9)/t3-/m0/s1
Key: ODHCTXKNWHHXJC-VKHMYHEASA-N
O=C(O)[C@H]1NC(=O)CC1
Related compounds
prolineExcept where otherwise noted, data are given for materials in their
standard state(at 25 °C [77 °F], 100 kPa).
N verify(
what is YN?)
Infobox referencesChemical compound
Pyroglutamic acid (also known as PCA, 5-oxoproline, pidolic acid) is a ubiquitous but understudied natural amino acid derivative in which the free amino group of glutamic acid or glutamine cyclizes to form a lactam.[1] The names of pyroglutamic acid conjugate base, anion, salts, and esters are pyroglutamate, 5-oxoprolinate, or pidolate.
Formation of pyroglutamic acid from N-terminal glutamine.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, or enzymatically converted by glutaminyl cyclases.[2] This is one of several forms of blocked N-termini 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.[3]
Pyroglutamic acid exists as two distinct enantiomers:
As first discovered in 1882, pyroglutamic acid can be formed by heating glutamic acid at 180 °C, which results in the loss of a molecule of water. In living cells, it is derived from glutathione through the action of an enzyme, γ-glutamyl cyclotransferase.[1] Pyroglutamic acid may function in glutamate storage, and acts to oppose the action of glutamate, including in the brain.[1] It also acts on the brain's cholinergic system;[4] Amyloid β containing pyroglutamic acid is increased in Alzheimer's disease; this may be part of the disease process.[5] Increased levels of pyroglutamic acid in the blood, leading to excess in the urine (5-oxoprolinuria), can occur following paracetamol overdose, as well as in certain inborn errors of metabolism, causing high anion gap metabolic acidosis.[1][6]
The sodium salt of pyroglutamic acid—known either as sodium pyroglutamate, sodium PCA, or sodium pidolate—is used for dry skin and hair products, as it is a humectant. It has low toxicity and is not a skin irritant, but its use in products is limited by a high price.[7][8]
L-pyroglutamic acid is sold online as a nootropic dietary supplement.[9][10]
Magnesium pidolate, the magnesium salt of pyroglutamic acid, is found in some mineral supplements. In a preclinical study, additional pharmacological properties of pyroglutamic acid were revealed such as anti-phosphodiesterase type 5, anti-angiotensin-converting enzyme, and anti-urease activities.[11]
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