Phosphoenolpyruvate (2-phosphoenolpyruvate, PEP) is the carboxylic acid derived from the enol of pyruvate and phosphate. It exists as an anion. PEP is an important intermediate in biochemistry. It has the highest-energy phosphate bond found (−61.9 kJ/mol) in organisms, and is involved in glycolysis and gluconeogenesis. In plants, it is also involved in the biosynthesis of various aromatic compounds, and in carbon fixation; in bacteria, it is also used as the source of energy for the phosphotransferase system.^[1][2]

Quick Facts Names, Identifiers ...

Phosphoenolpyruvic acid

Names
Preferred IUPAC name 2-(Phosphonooxy)prop-2-enoic acid
Other names Phosphoenolpyruvic acid, PEP
Identifiers
CAS Number	138-08-9 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:44897 Y
ChemSpider	980 Y
DrugBank	DB01819 Y
ECHA InfoCard	100.004.830
IUPHAR/BPS	4692
KEGG	C00074 Y
PubChem CID	1005
UNII	545YL308OW Y
CompTox Dashboard (EPA)	DTXSID80861797
InChI InChI=1S/C3H5O6P/c1-2(3(4)5)9-10(6,7)8/h1H2,(H,4,5)(H2,6,7,8) Y Key: DTBNBXWJWCWCIK-UHFFFAOYSA-N Y
SMILES O=C(O)C(OP(=O)(O)O)=C
Properties
Chemical formula	C3H5O6P
Molar mass	168.042
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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PEP is formed by the action of the enzyme enolase on 2-phosphoglyceric acid. Metabolism of PEP to pyruvic acid by pyruvate kinase (PK) generates adenosine triphosphate (ATP) via substrate-level phosphorylation. ATP is one of the major currencies of chemical energy within cells.

2-phospho-D-glycerate	Enolase		phosphoenolpyruvate	Pyruvate kinase		pyruvate
		H2O		ADP	ATP
		H2O

Compound C00631 at KEGG Pathway Database. Enzyme 4.2.1.11 at KEGG Pathway Database. Compound C00074 at KEGG Pathway Database. Enzyme 2.7.1.40 at KEGG Pathway Database. Compound C00022 at KEGG Pathway Database.

PEP is formed from the decarboxylation of oxaloacetate and hydrolysis of one guanosine triphosphate molecule. This reaction is catalyzed by the enzyme phosphoenolpyruvate carboxykinase (PEPCK). This reaction is a rate-limiting step in gluconeogenesis:^[3]

GTP + oxaloacetate → GDP + phosphoenolpyruvate + CO₂

Click on genes, proteins and metabolites below to link to respective articles.^{[§ 1]}

PEP may be used for the synthesis of chorismate through the shikimate pathway.^[4] Chorismate may then be metabolized into the aromatic amino acids (phenylalanine, tryptophan and tyrosine) and other aromatic compounds. The first step is when Phosphoenolpyruvate and erythrose-4-phosphate react to form 3-deoxy-D-arabinoheptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase.

In addition, in C₄ plants, PEP serves as an important substrate in carbon fixation. The chemical equation, as catalyzed by phosphoenolpyruvate carboxylase (PEP carboxylase), is:

PEP + HCO−3 → oxaloacetate