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1tdi
From Proteopedia
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'''Crystal Structure of hGSTA3-3 in Complex with Glutathione''' | '''Crystal Structure of hGSTA3-3 in Complex with Glutathione''' | ||
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[[Category: Singh, S V.]] | [[Category: Singh, S V.]] | ||
[[Category: Zimniak, P.]] | [[Category: Zimniak, P.]] | ||
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| - | [[Category: | + | [[Category: Hgsta3-3]] |
| - | [[Category: | + | [[Category: Steroid isomerase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 09:49:23 2008'' | |
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Revision as of 06:49, 3 May 2008
Crystal Structure of hGSTA3-3 in Complex with Glutathione
Overview
The crystal structure of human class alpha glutathione (GSH) S-transferase A3-3 (hGSTA3-3) in complex with GSH was determined at 2.4 A. Despite considerable amino acid sequence identity with other human class alpha GSTs (e.g., hGSTA1-1), hGSTA3-3 is unique due to its exceptionally high steroid double bond isomerase activity for the transformation of Delta(5)-androstene-3,17-dione (Delta(5)-AD) to Delta(4)-androstene-3,17-dione. A comparative analysis of the active centers of hGSTA1-1 and hGSTA3-3 reveals that residues in positions 12 and 208 may contribute to their disparate isomerase activity toward Delta(5)-AD. Substitution of these two residues of hGSTA3-3 with the corresponding residues in hGSTA1-1 followed by kinetic characterization of the wild-type and the mutant enzymes supported this prediction. On the basis of our model of the hGSTA3-3.GSH.Delta(5)-AD ternary complex and available biochemical data, we propose that the thiolate group of deprotonated GSH (GS(-)) serves as a base to initiate the reaction by accepting a proton from the steroid and the nonionized hydroxyl group of catalytic residue Y9 (HO-Y9) functions as part of a proton-conducting wire to transfer a proton back to the steroid. Residue R15 may function to stabilize the deprotonated thiolate group of GSH (GS(-)), and a GSH-bound water molecule may donate a hydrogen bond to the 3-keto group of Delta(5)-AD and thus help the thiolate of GS(-) to initiate the proton transfer and the subsequent stabilization of the reaction intermediate.
About this Structure
1TDI is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structure of human glutathione S-transferase A3-3 and mechanistic implications for its high steroid isomerase activity., Gu Y, Guo J, Pal A, Pan SS, Zimniak P, Singh SV, Ji X, Biochemistry. 2004 Dec 21;43(50):15673-9. PMID:15595823 Page seeded by OCA on Sat May 3 09:49:23 2008
Categories: Glutathione transferase | Homo sapiens | Single protein | Gu, Y. | Guo, J. | Ji, X. | Pal, A. | Pan, S S. | Singh, S V. | Zimniak, P. | Gst | Hgsta3-3 | Steroid isomerase
