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Temperature-dependent coordination in E. coli manganese superoxide dismutase.
Leandro C Tabares1, Néstor Cortez, Ileana Agalidis
1Service de Bioénergétique, DBJC, CNRS URA 2096, CEA Saclay, 91191 Gif-sur-Yvette, France, Centre de Génétique Moléculaire, CNRS, 91198 Gif-sur-Yvette, France.
Journal of the American Chemical Society
|April 21, 2005
Summary
Manganese superoxide dismutase (MnSOD) from E. coli exhibits temperature-dependent electron paramagnetic resonance spectra. A new hexacoordinate manganese(II) center forms at higher temperatures, indicating water molecule coordination.
Area of Science:
- Biochemistry
- Biophysics
- Enzymology
Background:
- Manganese superoxide dismutase (MnSOD) is crucial for cellular defense against oxidative stress.
- Understanding the structural dynamics of MnSOD is key to elucidating its catalytic mechanism.
Purpose of the Study:
- To investigate the temperature-dependent behavior of manganese(II) high-field electron paramagnetic resonance (EPR) spectra of E. coli MnSOD.
- To characterize the structural changes and coordination environment of the manganese(II) center in MnSOD under varying temperatures.
Main Methods:
- High-field electron paramagnetic resonance (EPR) spectroscopy was employed to study MnSOD.
- Temperature-dependent spectral analysis was performed in the range of 25-268 K.
- Thermodynamic parameters (enthalpy and entropy) were calculated for the observed equilibrium.
Main Results:
- Two distinct temperature dependences of the Mn(II) EPR spectrum were observed.
- A hexacoordinate Mn(II) center, formed by water coordination, was detected above 240 K.
- The equilibrium between pentacoordinate and hexacoordinate states was characterized by specific enthalpy and entropy values.
Conclusions:
- The study reveals temperature-induced structural changes in E. coli MnSOD, specifically the formation of a hexacoordinate manganese center.
- The findings provide insights into the ligand-metal distance dependence of the zero-field interaction and the dynamic nature of the Mn(II) active site.
- The results contribute to a deeper understanding of MnSOD structure-function relationships and its role in oxidative stress response.
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