4gss
From Proteopedia
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| - | [[Image:4gss.jpg|left|200px]] | + | [[Image:4gss.jpg|left|200px]] |
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| - | '''HUMAN GLUTATHIONE S-TRANSFERASE P1-1 Y108F MUTANT''' | + | {{Structure |
| + | |PDB= 4gss |SIZE=350|CAPTION= <scene name='initialview01'>4gss</scene>, resolution 2.5Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=GTX:S-HEXYLGLUTATHIONE'>GTX</scene> and <scene name='pdbligand=MES:2-(N-MORPHOLINO)-ETHANESULFONIC ACID'>MES</scene> | ||
| + | |ACTIVITY= [http://en.wikipedia.org/wiki/Glutathione_transferase Glutathione transferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.18 2.5.1.18] | ||
| + | |GENE= GTP_HUMAN ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens]) | ||
| + | }} | ||
| + | |||
| + | '''HUMAN GLUTATHIONE S-TRANSFERASE P1-1 Y108F MUTANT''' | ||
| + | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 4GSS is a [ | + | 4GSS is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4GSS OCA]. |
==Reference== | ==Reference== | ||
| - | Multifunctional role of Tyr 108 in the catalytic mechanism of human glutathione transferase P1-1. Crystallographic and kinetic studies on the Y108F mutant enzyme., Lo Bello M, Oakley AJ, Battistoni A, Mazzetti AP, Nuccetelli M, Mazzarese G, Rossjohn J, Parker MW, Ricci G, Biochemistry. 1997 May 20;36(20):6207-17. PMID:[http:// | + | Multifunctional role of Tyr 108 in the catalytic mechanism of human glutathione transferase P1-1. Crystallographic and kinetic studies on the Y108F mutant enzyme., Lo Bello M, Oakley AJ, Battistoni A, Mazzetti AP, Nuccetelli M, Mazzarese G, Rossjohn J, Parker MW, Ricci G, Biochemistry. 1997 May 20;36(20):6207-17. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9166793 9166793] |
[[Category: Glutathione transferase]] | [[Category: Glutathione transferase]] | ||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
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[[Category: transferase]] | [[Category: transferase]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 19:09:54 2008'' |
Revision as of 17:09, 20 March 2008
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| , resolution 2.5Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | and | ||||||
| Gene: | GTP_HUMAN (Homo sapiens) | ||||||
| Activity: | Glutathione transferase, with EC number 2.5.1.18 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
HUMAN GLUTATHIONE S-TRANSFERASE P1-1 Y108F MUTANT
Overview
The possible role of the hydroxyl group of Tyr 108 in the catalytic mechanism of human glutathione transferase P1-1 has been investigated by means of site-directed mutagenesis, steady-state kinetic analysis, and crystallographic studies. Three representative cosubstrates have been used, i.e. ethacrynic acid, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, and 1-chloro-2,4-dinitrobenzene. In the presence of ethacrynic acid, the enzyme follows a rapid equilibrium random bi-bi mechanism with a rate-limiting step which occurs after the addition of the substrates and before the release of products. The replacement of Tyr 108 with Phe yields a 14-fold decrease of k(cat), while it does not change appreciably the affinity of the H site for the substrate. In this case, it would appear that the role of the hydroxyl function is to stabilize the transition state for the chemical step, i.e. the Michael addition of GSH to the electrophilic substrate. Crystallographic data are compatible with this conclusion showing the hydroxyl group of Y108 in hydrogen bonding distance of the ketone moiety of ethacrynic acid [Oakley, A. J., Rossjohn, J., Lo Bello, M., Caccuri, A. M., Federici, G., & Parker, M. W. (1997) Biochemistry 36, 576-585]. Moreover, no structural differences are observed between the Y108F mutant and the wild type, suggesting that the removal of the hydroxyl group is solely responsible for the loss of activity. A different involvement of Tyr 108 appears in the catalyzed conjugation of 7-chloro-4-nitrobenz-2-oxa-1,3-diazole with GSH in which the rate-limiting step is of a physical nature, probably a structural transition of the ternary complex. The substitution of Tyr 108 yields an approximately 7-fold increase of k(cat) and a constant k(cat)/Km(NBD-Cl) value. Lack of a critical hydrogen bond between 7-chloro-4-nitrobenz-2-oxa-1,3-diazole and Tyr 108 appears to be the basis of the increased k(cat). In the 1-chloro-2,4-dinitrobenzene/GSH system, no appreciable changes of kinetics parameters are found in the Y108F mutant. We conclude that Y108 has a multifunctional role in glutathione transferase P1-1 catalysis, depending on the nature of the electrophilic cosubstrate.
About this Structure
4GSS is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Multifunctional role of Tyr 108 in the catalytic mechanism of human glutathione transferase P1-1. Crystallographic and kinetic studies on the Y108F mutant enzyme., Lo Bello M, Oakley AJ, Battistoni A, Mazzetti AP, Nuccetelli M, Mazzarese G, Rossjohn J, Parker MW, Ricci G, Biochemistry. 1997 May 20;36(20):6207-17. PMID:9166793
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