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| {{STRUCTURE_1bay| PDB=1bay | SCENE= }} | | {{STRUCTURE_1bay| PDB=1bay | SCENE= }} |
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| '''GLUTATHIONE S-TRANSFERASE YFYF CYS 47-CARBOXYMETHYLATED CLASS PI, FREE ENZYME'''
| | ===GLUTATHIONE S-TRANSFERASE YFYF CYS 47-CARBOXYMETHYLATED CLASS PI, FREE ENZYME=== |
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| ==Overview==
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| The three-dimensional structure of mouse liver glutathione S-transferase P1-1 carboxymethylated at Cys-47 and its complex with S-(p-nitrobenzyl)glutathione have been determined by x-ray diffraction analysis. The structure of the modified enzyme described here is the first structural report for a Pi class glutathione S-transferase with no glutathione, glutathione S-conjugate, or inhibitor bound. It shows that part of the active site area, which includes helix alphaB and helix 310B, is disordered. However, the environment of Tyr-7, an essential residue for the catalytic reaction, remains unchanged. The position of the sulfur atom of glutathione is occupied in the ligand-free enzyme by a water molecule that is at H-bond distance from Tyr-7. We do not find any structural evidence for a tyrosinate form, and therefore our results suggest that Tyr-7 is not acting as a general base abstracting the proton from the thiol group of glutathione. The binding of the inhibitor S-(p-nitrobenzyl)-glutathione to the carboxymethylated enzyme results in a partial restructuring of the disordered area. The modification of Cys-47 sterically hinders structural organization of this region, and although it does not prevent glutathione binding, it significantly reduces the affinity. A detailed kinetic study of the modified enzyme indicates that the carboxymethylation increases the Km for glutathione by 3 orders of magnitude, although the enzyme can function efficiently under saturating conditions.
| | The line below this paragraph, {{ABSTRACT_PUBMED_9446594}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 9446594 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_9446594}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Multigene family]] | | [[Category: Multigene family]] |
| [[Category: Transferase]] | | [[Category: Transferase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:17:30 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 18:44:09 2008'' |
