Phosphoenolpyruvic acid

Phosphoenolpyruvic acid
IUPAC name 2-(phosphonooxy)acrylic acid
Other names Phosphoenolpyruvic acid, PEP
Identifiers
CAS number	138-08-9 Y
PubChem	1005
ChemSpider	980 Y
DrugBank	DB01819
ChEBI	CHEBI:44897 Y
Jmol-3D images	Image 1
SMILES O=C(O)C(OP(=O)(O)O)=C
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
Properties
Molecular formula	C3H5O6P
Molar mass	168.04 g mol−1
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Phosphoenolpyruvic acid (PEP), or phosphoenolpyruvate as the anion, is an important chemical compound in biochemistry. It has the high-energy phosphate bond found (-61.9 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; in bacteria, it is also used as the source of energy for the phosphotransferase system.

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:

GTP + oxaloacetate → GDP + phosphoenolpyruvate + CO₂

In plants

PEP may be used for the synthesis of chorismate through the shikimate pathway. 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 + HCO₃^- → oxaloacetate