Sandbox Reserved 714: Difference between revisions
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<StructureSection load='1s8o_mm1.pdb' size='400' side='left' caption='X-ray crystal structure of hsEH (PDB entry [[1s8o]])' scene='Sandbox_Reserved_714/Initial_scene/2'> | <StructureSection load='1s8o_mm1.pdb' size='400' side='left' caption='X-ray crystal structure of hsEH (PDB entry [[1s8o]])' scene='Sandbox_Reserved_714/Initial_scene/2'> | ||
== | == General structure == | ||
<scene name='Sandbox_Reserved_714/Initial_scene/2'>Reset</scene> | <scene name='Sandbox_Reserved_714/Initial_scene/2'>Reset</scene> | ||
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== Mechanism == | == Mechanism == | ||
The C-terminal domain is called Cytosolic epoxide hydrolase 2: it catalyzes the trans-addition of water to epoxides in order to product glycols<ref>PMID:15822179</ref>. The <scene name='Sandbox_Reserved_714/Cter_activesite/3'>active site</scene> is made of five residues. The 3D structure of this active site is maintained by hydrogen bonds, including those created by D496. The two tyrosines (Y383 and Y466) assist the proper positioning of the substrate by polarizing it, thanks to their hydroxyl groups. D335 | The C-terminal domain is called Cytosolic epoxide hydrolase 2: it catalyzes the trans-addition of water to epoxides in order to product glycols<ref>PMID:15822179</ref>. The <scene name='Sandbox_Reserved_714/Cter_activesite/3'>active site</scene> is made of five residues. The 3D structure of this active site is maintained by hydrogen bonds, including those created by D496. The two tyrosines (Y383 and Y466) assist the proper positioning of the substrate by polarizing it, thanks to their hydroxyl groups. D335 acts as a nucleophilic acid. Finally, H524 plays the role of a base in order to release the final product. | ||
The reaction proceeds in two steps, including the formation of a covalent intermediate. | |||
First, the substrate (epoxide) is accepted in the active site and its oxygen forms hydrogen bonds with Y383 and Y466. The oxygen of D335 attacks one of the two carbons included in the epoxide function. As a result, the oxygen of the subtrate takes the hydrogen of the hydroxyl function of Y466: the covalent intermediate is formed, and linked to D335. | |||
The N-terminal domain is responsible of the Mg<sup>2+</sup> dependant hydrolysis of p-nitrophenyl phosphate <ref>PMID:15096040</ref>. Its <scene name='Sandbox_Reserved_714/Nter_activesite/1'>active site</scene> contains several conserved aspartates in phosphatases and phosphonatases: D9, D11, D184 and D185. This enzymatic activity is Mg<sup>2+</sup> dependant, because the structure of the active site is in its optimal conformation when the cation makes coordination interactions. When the catalytic activity of the N-term domain is available, Magnesium is octahedrally coordinated with the four aspartates, one water molecule and the phosphate belonging to the substrate. | The N-terminal domain is responsible of the Mg<sup>2+</sup> dependant hydrolysis of p-nitrophenyl phosphate <ref>PMID:15096040</ref>. Its <scene name='Sandbox_Reserved_714/Nter_activesite/1'>active site</scene> contains several conserved aspartates in phosphatases and phosphonatases: D9, D11, D184 and D185. This enzymatic activity is Mg<sup>2+</sup> dependant, because the structure of the active site is in its optimal conformation when the cation makes coordination interactions. When the catalytic activity of the N-term domain is available, Magnesium is octahedrally coordinated with the four aspartates, one water molecule and the phosphate belonging to the substrate. | ||