Mössbauer spectroscopy and DFT calculations on all protonation states of the 2Fe-2S cluster of the Rieske protein
| Autor: | Hendrik Auerbach, Juliusz A. Wolny, Christina S. Müller, Antonio J. Pierik, Kathrin Stegmaier, Volker Schünemann |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Nuclear and High Energy Physics biology Chemistry Protonation Crystal structure Electronic structure 010402 general chemistry Condensed Matter Physics Photochemistry 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences 03 medical and health sciences Electron transfer Crystallography 030104 developmental biology Mössbauer spectroscopy Rieske protein biology.protein Cluster (physics) Density functional theory Physical and Theoretical Chemistry |
| Zdroj: | Hyperfine Interactions. 238 |
| ISSN: | 1572-9540 0304-3843 |
| Popis: | The Thermus thermophilus Rieske protein (TtRP) contains a 2Fe-2S cluster with one iron (Fe-Cys) coordinated by four sulfur atoms (2xS2− and 2xCys) and one iron (Fe-His) by two sulfur and two nitrogen atoms (2xS2−, His134 and His154). Here, the protein is investigated at three pH values (6.0, 8.5 and 10.5) in order to elucidate the protonation states of the His-ligands. Examination of the effect of protonation on the electronic structure of the cluster via Mossbauer spectroscopy gives a deeper understanding of the coupling of electron transfer to the protonation state of the His-ligands. Two components (1 referring to Fe-Cys and 2 to Fe-His) with parameters typical for a diamagnetic [2Fe-2S]2+ cluster are detected. The Mossbauer parameters and the protonation state clearly correlate: while δ remains almost pH-independent with δ 1 (pH6.0) = 0.23 (± 0.01) mms− 1 and δ 1 (pH10.5) = 0.24 (± 0.01) mms− 1 for Fe-Cys, it decreases for Fe-His from δ 2 (pH6.0) = 0.34 (± 0.01) mms− 1 to δ 2 (pH10.5) = 0.28 (± 0.01) mms− 1. ΔE Q changes from ΔE Q1 (pH6.0) = 0.57 (± 0.01) mms− 1 to ΔE Q1 (pH10.5) = 0.45 (± 0.01) mms− 1 and from ΔE Q2 (pH6.0) = 1.05 (± 0.01) mms− 1 to ΔE Q2 (pH10.5) = 0.71 (± 0.01) mms− 1. Density functional theory (DFT)-calculations based on the crystal structure (pdb 1NYK) (Hunsicker-Wang et al. Biochemistry 42, 7303, 2003) have been performed for the Rieske-cluster with different His-ligand protonation states, reproducing the experimentally observed trend. |
| Databáze: | OpenAIRE |
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