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Phosphoenolpyruvate

Phosphoenolpyruvate

IUPAC name	2-phosphonooxyprop-2-enoic acid
Other names	Phosphoenolpyruvic acid, PEP
Identifiers
CAS number	138-08-9
PubChem	1005
SMILES	C=C(C(=O)O)OP(=O)(O)O
Properties
Molecular formula	C₃H₅O₆P
Molar mass	168.042
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Phosphoenolpyruvate (synonyms: phosphoenolpyruvic acid, PEP) is an important chemical compound in biochemistry. It has the highest energy phosphate bond found (-62 KJ/mol) in living 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.

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In glycolysis

PEP is formed by the action of the enzyme enolase on 2-phosphoglycerate. Metabolism of PEP to pyruvate by pyruvate kinase (PK) generates 1 molecule of 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

	Enolase			Pyruvate kinase

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.

In gluconeogenesis

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:^[1]

GTP + oxaloacetate → GDP + phosphoenolpyruvate + CO₂

In plants

PEP may be used for the synthesis of chorismate through the shikimate pathway.^[2] Chorismate may then be metabolized into the aromatic amino acids (phenylalanine, tryptophan and tyrosine) and other aromatic compounds.

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 + CO₂ → oxaloacetate

References

^ InterPro: IPR008209 Phosphoenolpyruvate carboxykinase, GTP-utilising. Retrieved on 2007-08-17.
^ BioCarta - Charting Pathways of Life. Retrieved on 2007-08-17.