5-エノイルピルビニルシキミ酸-3-リン酸合成酵素、EPSP合成酵素、EPSPシンターゼ
出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/15 22:57:52」(JST)
| EPSP Synthase (3-phosphoshikimate 1-carboxyvinyltransferase) | |||||||||
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EPSP synthase liganded with shikimate.[1]
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| Identifiers | |||||||||
| EC number | 2.5.1.19 | ||||||||
| CAS number | 9068-73-9 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
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| EPSP synthase (3-phosphoshikimate 1-carboxyvinyltransferase) | |||||||||
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Ribbon diagram of EPSP synthase
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| Identifiers | |||||||||
| Symbol | EPSP_synthase | ||||||||
| Pfam | PF00275 | ||||||||
| InterPro | IPR001986 | ||||||||
| PROSITE | PDOC00097 | ||||||||
| SCOP | 1eps | ||||||||
| SUPERFAMILY | 1eps | ||||||||
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5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is an enzyme that catalyzes the chemical reaction:
Thus, the two substrates of this enzyme are phosphoenolpyruvate and 3-phospho-shikimate, whereas its two products are phosphate and 5-enolpyruvylshikimate-3-phosphate.
The enzyme belongs to the family of transferases, to be specific those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is phosphoenolpyruvate:3-phosphoshikimate 5-O-(1-carboxyvinyl)-transferase. Other names in common use include:
The enzyme participates in biosynthesis of the aromatic amino acids phenylalanine, tyrosine and tryptophan. The enzyme is a target for herbicides as these amino acids are only synthesized in plants and microorganisms. Glyphosate acts as a competitive inhibitor for phosphoenolpyruvate and is used as a broad-spectrum systemic herbicide.[2][3]
The shikimate pathway is a seven step metabolic route used by bacteria, fungi, and plants for the biosythesis of aromatic amino acids (phenylalanine, tyrosine, and tryptophan). The fourth aromatic amino acid tyrosine can be synthesized from phenylalanine. This pathway is not found in animals, hence the products of this pathway represent essential amino acids that must be obtained from the animal's diet.
EPSP synthase is a monomeric enzyme. It is composed of two domains, which are joined by protein strands. This strand acts as a hinge, and can bring the two protein domains closer together. When a substrate binds to the enzyme, ligand bonding causes the two parts of the enzyme to clamp down around the substrate in the active site.
EPSP synthase catalyzes the reaction which converts shikimate-3-phosphate plus phosphoenolpyruvate to 5-enolpyruvylshikimate-3-phosphate (EPSP).
Glyphosate is a chemical herbicide which kills plants by inhbiting the shikimate pathway. It targets EPSP synthase, the enzyme that catalyzes the conversion of shikimate-3-phosphate and phosphoenolpyruvate into EPSP. Glyphosate is a competitive inhibitor of the enzyme. Glyphosate resembles the transition state that transforms the reactants into products in the reaction that is catalyzed by EPSP synthase. Hence glyphosate (as a transition state analog) binds more tightly to EPSP synthase than its natural substrate and thereby prevents binding of substrate to the enzyme.[2]
This binding leads to inhibition of the enzyme and shuts down the entire pathway. Eventually this results in plant death from lack of aromatic amino acids used to make pigments and flavonoids the plant requires to survive. Glyphosate does not inhibit aromatic acid synthesis in animals and humans as they lack the shikimate pathway and aromatic amino acids are obtained from their diet. However, beneficial gut bacteria isolated from chickens was found to be affected through inhibition at 0.075-0.15 ppm of glyphosate while pathogenic bacteria were more resistant.[4]
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| リンク元 | 「5-エノイルピルビニルシキミ酸-3-リン酸合成酵素」「5-enolpyruvylshikimate-3-phosphate synthase」「3-phosphoshikimate 1-carboxyvinyltransferase」「EPSP合成酵素」「EPSPシンターゼ」 |
| 関連記事 | 「EPS」「EP」「synthase」「EPSPs」「EPSP」 |
5-エノイルピルビニルシキミ酸-3-リン酸合成酵素、5-エノイルピルビニルシキミ酸-3-リン酸シンターゼ
[★] 興奮性シナプス後電位 excitatory postsynaptic potentials