3q18 | pdb_00003q18

Human Glutathione Transferase O2

spinqualitylabelsall models 3q18, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3q18 is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CL, GOL, PEG Related: 1eem, 3q19 Gene: GSTO2 (Homo sapiens) Activity: Glutathione transferase, with EC number 2.5.1.18 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The reduction of dehydroascorbate (DHA) to ascorbic acid (AA) is a vital cellular function. The omega-class glutathione S-transferases (GSTs) catalyze several reductive reactions in cellular biochemistry, including DHA reduction. In humans, two isozymes (GSTO1-1 and GSTO2-2) with significant DHA reductase (DHAR) activity are found, sharing 64% sequence identity. While the activity of GSTO2-2 is higher, it is significantly more unstable in vitro. We report the first crystal structures of human GSTO2-2, stabilized through site-directed mutagenesis and determined at 1.9 A resolution in the presence and absence of glutathione (GSH). The structure of a human GSTO1-1 has been determined at 1.7 A resolution in complex with the reaction product AA, which unexpectedly binds in the G-site, where the glutamyl moiety of GSH binds. The structure suggests a similar mode of ascorbate binding in GSTO2-2. This is the first time that a non-GSH-based reaction product has been observed in the G-site of any GST. AA stacks against a conserved aromatic residue, F34 (equivalent to Y34 in GSTO2-2). Mutation of Y34 to alanine in GSTO2-2 eliminates DHAR activity. From these structures and other biochemical data, we propose a mechanism of substrate binding and catalysis of DHAR activity. Structural Insights into the Dehydroascorbate Reductase Activity of Human Omega-Class Glutathione Transferases.,Zhou H, Brock J, Liu D, Board PG, Oakley AJ J Mol Biol. 2012 Apr 18. PMID:22522127 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glutathione S-transferase

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