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'Phosphoenolpyruvate' (synonyms: 'Phosphoenolpyruvic acid', 'PEP') is an important chemical compound in biochemistry. It has a high energy phosphate bond, 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

In gluconeogenesis

In plants

References

External links

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.

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.
Additionally, 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
2. BioCarta - Charting Pathways of Life

External links