A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy
The S<sub>2</sub> state produces two basic electron paramagnetic resonance signal types due to the manganese cluster in oxygen-evolving complex, which are influenced by the solvents, and cryoprotectant added to the photosystem II samples. It is presumed that a single manganese center oxi...
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| Format: | Article |
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MDPI AG
2021-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/26/9/2699 |
| _version_ | 1827693322082189312 |
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| author | Bernard Baituti Sebusi Odisitse |
| author_facet | Bernard Baituti Sebusi Odisitse |
| author_sort | Bernard Baituti |
| collection | DOAJ |
| description | The S<sub>2</sub> state produces two basic electron paramagnetic resonance signal types due to the manganese cluster in oxygen-evolving complex, which are influenced by the solvents, and cryoprotectant added to the photosystem II samples. It is presumed that a single manganese center oxidation occurs on S<sub>1</sub> → S<sub>2</sub> state transition. The S<sub>2</sub> state has readily visible multiline and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi><mn>4.1</mn></mrow></semantics></math></inline-formula> electron paramagnetic resonance signals and hence it has been the most studied of all the Kok cycle intermediates due to the ease of experimental preparation and stability. The S<sub>2</sub> state was studied using electron paramagnetic resonance spectroscopy at X-band frequencies. The aim of this study was to determine the spin states of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi><mn>4.1</mn></mrow></semantics></math></inline-formula> signal. The multiline signal was observed to arise from a ground state spin ½ centre while the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi></mrow></semantics></math></inline-formula>4.1 signal generated at ≈140 K NIR illumination was proposed to arise from a spin <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mn>5</mn><mn>2</mn></mfrac></mrow></semantics></math></inline-formula> center with rhombic distortion. The ‘ground’ state <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>g</mi></semantics></math></inline-formula>4.1 signal was generated solely or by conversion from the multiline. The data analysis methods used involved numerical simulations of the experimental spectra on relevant models of the oxygen-evolving complex cluster. A strong focus in this paper was on the ‘ground’ state <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>g</mi></semantics></math></inline-formula>4.1 signal, whether it is a rhombic <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mn>5</mn><mn>2</mn></mfrac></mrow></semantics></math></inline-formula> spin state signal or an axial <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac></mrow></semantics></math></inline-formula> spin state signal. The data supported an X-band CW-EPR-generated <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>g</mi></semantics></math></inline-formula>4.1 signal as originating from a near rhombic spin 5/2 of the S<sub>2</sub> state of the PSII manganese cluster. |
| first_indexed | 2024-03-10T11:42:02Z |
| format | Article |
| id | doaj.art-0ea6bcf4cdf044c7aa78fc2c593dbc99 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T11:42:02Z |
| publishDate | 2021-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-0ea6bcf4cdf044c7aa78fc2c593dbc992023-11-21T18:23:39ZengMDPI AGMolecules1420-30492021-05-01269269910.3390/molecules26092699A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance SpectroscopyBernard Baituti0Sebusi Odisitse1Department of Chemical and Forensic Science, Faculty of Science, Botswana International University of Science and Technology, Private Bag 16, Palapye, BotswanaDepartment of Chemical and Forensic Science, Faculty of Science, Botswana International University of Science and Technology, Private Bag 16, Palapye, BotswanaThe S<sub>2</sub> state produces two basic electron paramagnetic resonance signal types due to the manganese cluster in oxygen-evolving complex, which are influenced by the solvents, and cryoprotectant added to the photosystem II samples. It is presumed that a single manganese center oxidation occurs on S<sub>1</sub> → S<sub>2</sub> state transition. The S<sub>2</sub> state has readily visible multiline and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi><mn>4.1</mn></mrow></semantics></math></inline-formula> electron paramagnetic resonance signals and hence it has been the most studied of all the Kok cycle intermediates due to the ease of experimental preparation and stability. The S<sub>2</sub> state was studied using electron paramagnetic resonance spectroscopy at X-band frequencies. The aim of this study was to determine the spin states of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi><mn>4.1</mn></mrow></semantics></math></inline-formula> signal. The multiline signal was observed to arise from a ground state spin ½ centre while the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi></mrow></semantics></math></inline-formula>4.1 signal generated at ≈140 K NIR illumination was proposed to arise from a spin <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mn>5</mn><mn>2</mn></mfrac></mrow></semantics></math></inline-formula> center with rhombic distortion. The ‘ground’ state <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>g</mi></semantics></math></inline-formula>4.1 signal was generated solely or by conversion from the multiline. The data analysis methods used involved numerical simulations of the experimental spectra on relevant models of the oxygen-evolving complex cluster. A strong focus in this paper was on the ‘ground’ state <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>g</mi></semantics></math></inline-formula>4.1 signal, whether it is a rhombic <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mn>5</mn><mn>2</mn></mfrac></mrow></semantics></math></inline-formula> spin state signal or an axial <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac></mrow></semantics></math></inline-formula> spin state signal. The data supported an X-band CW-EPR-generated <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>g</mi></semantics></math></inline-formula>4.1 signal as originating from a near rhombic spin 5/2 of the S<sub>2</sub> state of the PSII manganese cluster.https://www.mdpi.com/1420-3049/26/9/2699photosystem IIspectrum<i>g</i>4.1 signalmultilineoxidationsimulation |
| spellingShingle | Bernard Baituti Sebusi Odisitse A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy Molecules photosystem II spectrum <i>g</i>4.1 signal multiline oxidation simulation |
| title | A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy |
| title_full | A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy |
| title_fullStr | A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy |
| title_full_unstemmed | A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy |
| title_short | A Computational Study of the S<sub>2</sub> State in the Oxygen-Evolving Complex of Photosystem II by Electron Paramagnetic Resonance Spectroscopy |
| title_sort | computational study of the s sub 2 sub state in the oxygen evolving complex of photosystem ii by electron paramagnetic resonance spectroscopy |
| topic | photosystem II spectrum <i>g</i>4.1 signal multiline oxidation simulation |
| url | https://www.mdpi.com/1420-3049/26/9/2699 |
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