22GS

HUMAN GLUTATHIONE S-TRANSFERASE P1-1 Y49F MUTANT

22GS の概要

• エントリーDOI: 10.2210/pdb22gs/pdb
• 分子名称: GLUTATHIONE S-TRANSFERASE P1-1, 2-(N-MORPHOLINO)-ETHANESULFONIC ACID (3 entities in total)
• 機能のキーワード: transferase, glutathione, pi, detoxification, y49f
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Cytoplasm : P09211
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 47309.25

構造登録者

Oakley, A.J. (登録日: 1998-03-10, 公開日: 1999-03-23, 最終更新日: 2024-05-22)

主引用文献

Ortiz-Salmeron, E.,Nuccetelli, M.,Oakley, A.J.,Parker, M.W.,Lo Bello, M.,Garcia-Fuentes, L.
Thermodynamic description of the effect of the mutation Y49F on human glutathione transferase P1-1 in binding with glutathione and the inhibitor S-hexylglutathione.
J.Biol.Chem., 278:46938-46948, 2003

PubMed Abstract: The thermodynamics of binding of both the substrate glutathione (GSH) and the competitive inhibitor S-hexylglutathione to the mutant Y49F of human glutathione S-transferase (hGST P1-1), a key residue at the dimer interface, has been investigated by isothermal titration calorimetry and fluorescence spectroscopy. Calorimetric measurements indicated that the binding of these ligands to both the Y49F mutant and wild-type enzyme is enthalpically favorable and entropically unfavorable over the temperature range studied. The affinity of these ligands for the Y49F mutant is lower than those for the wild-type enzyme due mainly to an entropy change. Therefore, the thermodynamic effect of this mutation is to decrease the entropy loss due to binding. Calorimetric titrations in several buffers with different ionization heat amounts indicate a release of protons when the mutant binds GSH, whereas protons are taken up in binding S-hexylglutathione at pH 6.5. This suggests that the thiol group of GSH releases protons to buffer media during binding and a group with low pKa (such as Asp98) is responsible for the uptake of protons. The temperature dependence of the free energy of binding, DeltaG0, is weak because of the enthalpy-entropy compensation caused by a large heat capacity change. The heat capacity change is -199.5 +/- 26.9 cal K-1 mol-1 for GSH binding and -333.6 +/- 28.8 cal K-1 mol-1 for S-hexylglutathione binding. The thermodynamic parameters are consistent with the mutation Tyr49 --> Phe, producing a slight conformational change in the active site.

PubMed: 12937169
DOI: 10.1074/jbc.M305043200

実験手法

X-RAY DIFFRACTION (1.9 Å)