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GLUTATHIONE S-TRANSFERASE YFYF CYS 47-CARBOXYMETHYLATED CLASS PI, FREE ENZYME
Structural highlights
FunctionGSTP1_MOUSE Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. Can metabolize 1-chloro-2,4-dinitrobenzene. Regulates negatively CDK5 activity via p25/p35 translocation to prevent neurodegeneration (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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 three-dimensional structure of Cys-47-modified mouse liver glutathione S-transferase P1-1. Carboxymethylation dramatically decreases the affinity for glutathione and is associated with a loss of electron density in the alphaB-310B region.,Vega MC, Walsh SB, Mantle TJ, Coll M J Biol Chem. 1998 Jan 30;273(5):2844-50. PMID:9446594[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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