Determining the oxidation state of elements by X-ray crystallography
Frank Lennartz1, Jae Hun Jeoung2, Stefan Ruenger2
1Macromolecular Crystallography, Helmholtz-Zentrum Berlin, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.
Acta Crystallographica. Section D, Structural Biology
|February 1, 2022
Summary
Spatially resolved anomalous dispersion (SpReAD) refinement can determine metal ion oxidation states in small redox proteins. This study demonstrates SpReAD analysis on Sulfolobus tokodaii sulerythrin, revealing distinct iron ion oxidation states.
Area of Science:
- Biochemistry
- Structural Biology
- Biophysics
Background:
- Protein-mediated redox reactions are vital in biological processes, often involving metal ion cofactors.
- Understanding these reactions requires correlating protein structure with metal cofactor oxidation states.
- Spatially resolved anomalous dispersion (SpReAD) refinement is a crystallographic method for determining metal redox states.
Purpose of the Study:
- To assess the feasibility of SpReAD refinement for small, non-iron-sulfur redox centers.
- To characterize the binuclear metal center in Sulfolobus tokodaii sulerythrin using SpReAD analysis.
Main Methods:
- SpReAD refinement applied to crystallographic data of Sulfolobus tokodaii sulerythrin.
- Treatment of crystals with hydrogen peroxide (H2O2) to induce redox changes.
- High X-ray dose data collection to investigate potential photoreduction effects.
Main Results:
- SpReAD analysis successfully characterized the binuclear metal center in sulerythrin.
- Differences in oxidation states between individual iron ions were observed after H2O2 treatment.
- High X-ray doses induced photoreduction of the metal center, highlighting the need for dose control.
Conclusions:
- SpReAD refinement is applicable to small, non-iron-sulfur redox centers, extending its utility.
- Accurate determination of metal oxidation states via SpReAD requires careful management of X-ray dose to prevent photoreduction.
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