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Phosphoenolpyruvate (2-phosphoenolpyruvate, PEP) is the ester 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]

Phosphoenolpyruvic acid
PhosphoenolpyruvateChemDr.png
Names
IUPAC name
2-(phosphonooxy)acrylic acid
Other names
Phosphoenolpyruvic acid, PEP
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.004.830
Properties
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).
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Infobox references

Contents

In glycolysisEdit

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
   
  Enolase  

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 gluconeogenesisEdit

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

Interactive pathway mapEdit

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

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|{{{bSize}}}px|alt=Glycolysis and Gluconeogenesis edit]]
Glycolysis and Gluconeogenesis edit
  1. ^ The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534".

In plantsEdit

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.

 
Biosynthesis of DAHP from phosphoenolpyruvate and erythrose-4-phosphate

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

ReferencesEdit

  1. ^ Berg, Jeremy M.; Tymoczko, Stryer (2002). Biochemistry (5th ed.). New York: W.H. Freeman and Company. ISBN 0-7167-3051-0.
  2. ^ Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.
  3. ^ "InterPro: IPR008209 Phosphoenolpyruvate carboxykinase, GTP-utilising". Retrieved 2007-08-17.
  4. ^ "BioCarta - Charting Pathways of Life". Retrieved 2007-08-17.