1c72

TYR115, GLN165 AND TRP209 CONTRIBUTE TO THE 1,2-EPOXY-3-(P-NITROPHENOXY)PROPANE CONJUGATING ACTIVITIES OF GLUTATHIONE S-TRANSFERASE CGSTM1-1

spinqualitylabelsall models 1c72, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1c72 is a 4 chain structure with sequence from Gallus gallus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.8Å Ligands: EPY Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function GSTM2_CHICK Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. 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 PubMed We investigated the epoxidase activity of a class mu glutathione S-transferase (cGSTM1-1), using 1,2-epoxy-3-(p-nitrophenoxy)propane (EPNP) as substrate. Trp209 on the C-terminal tail, Arg107 on the alpha4 helix, Asp161 and Gln165 on the alpha6 helix of cGSTM1-1 were selected for mutagenesis and kinetic studies. A hydrophobic side-chain at residue 209 is needed for the epoxidase activity of cGSTM1-1. Replacing Trp209 with histidine, isoleucine or proline resulted in a fivefold to 28-fold decrease in the k(cat)(app) of the enzyme, while a modest 25 % decrease in the k(cat)(app) was observed for the W209F mutant. The rGSTM1-1 enzyme has serine at the correponding position. The k(cat)(app) of the S209W mutant is 2. 5-fold higher than that of the wild-type rGSTM1-1. A charged residue is needed at position 107 of cGSTM1-1. The K(m)(app)(GSH) of the R107L mutant is 38-fold lower than that of the wild-type enzyme. On the contrary, the R107E mutant has a K(m)(app)(GSH) and a k(cat)(app) that are 11-fold and 35 % lower than those of the wild-type cGSTM1-1. The substitutions of Gln165 with Glu or Leu have minimal effect on the affinity of the mutants towards GSH or EPNP. However, a discernible reduction in k(cat)(app) was observed. Asp161 is involved in maintaining the structural integrity of the enzyme. The K(m)(app)(GSH) of the D161L mutant is 616-fold higher than that of the wild-type enzyme. In the hydrogen/deuterium exchange experiments, this mutant has the highest level of deuteration among all the proteins tested.We also elucidated the structure of cGSTM1-1 co-crystallized with the glutathionyl-conjugated 1, 2-epoxy-3-(p-nitrophenoxy)propane (EPNP) at 2.8 A resolution. The product found in the active site was 1-hydroxy-2-(S-glutathionyl)-3-(p-nitrophenoxy)propane, instead of the conventional 2-hydroxy isomer. The EPNP moiety orients towards Arg107 and Gln165 in dimer AB, and protrudes into a hydrophobic region formed by the loop connecting beta1 and alpha1 and part of the C-terminal tail in dimer CD. The phenoxyl ring forms strong ring stacking with the Trp209 side-chain in dimer CD. We hypothesize that these two conformations represent the EPNP moiety close to the initial and final stages of the reaction mechanism, respectively. Tyr115, gln165 and trp209 contribute to the 1, 2-epoxy-3-(p-nitrophenoxy)propane-conjugating activity of glutathione S-transferase cGSTM1-1.,Chern MK, Wu TC, Hsieh CH, Chou CC, Liu LF, Kuan IC, Yeh YH, Hsiao CD, Tam MF J Mol Biol. 2000 Jul 28;300(5):1257-69. PMID:10903867 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glutathione S-transferase 3D structures

Proteopedia Page Contributors and Editors (what is this?)

OCA