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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.

Contents

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

  1. ^ InterPro: IPR008209 Phosphoenolpyruvate carboxykinase, GTP-utilising. Retrieved on 2007-08-17.
  2. ^ BioCarta - Charting Pathways of Life. Retrieved on 2007-08-17.
 v • d • e 
Glycolysis Metabolic Pathway
Glucose Hexokinase Glucose-6-phosphate Phosphoglucoisomerase Fructose 6-phosphate Phosphofructokinase Fructose 1,6-bisphosphate Fructose bisphosphate aldolase Dihydroxyacetone phosphate Glyceraldehyde 3-phosphate Triosephosphate isomerase Glyceraldehyde 3-phosphate Glyceraldehyde phosphate dehydrogenase
ATP ADP ATP ADP NAD+ + Pi NADH + H+
+ 2
NAD+ + Pi NADH + H+
1,3-Bisphosphoglycerate Phosphoglycerate kinase 3-Phosphoglycerate Phosphoglycerate mutase 2-Phosphoglycerate Enolase Phosphoenolpyruvate Pyruvate kinase Pyruvate Pyruvate dehydrogenase Acetyl-CoA
ADP ATP H2O ADP ATP CoA + NAD+ NADH + H+ + CO2
2 2 2 2 2 2
ADP ATP H2O
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Phosphoenolpyruvate". A list of authors is available in Wikipedia.
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