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Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex

Manganese (Mn) serves as the catalytic center for water splitting in photosystem II (PSII), despite the abundance of iron (Fe) on earth. As a first step toward why Mn and not Fe is employed by Nature in the water oxidation catalyst, we investigated the Fe(4)CaO(5) cluster in the PSII protein environ...

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Autores principales: Saito, Masahiro, Saito, Keisuke, Ishikita, Hiroshi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10382916/
https://www.ncbi.nlm.nih.gov/pubmed/37520740
http://dx.doi.org/10.1016/j.isci.2023.107352
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author Saito, Masahiro
Saito, Keisuke
Ishikita, Hiroshi
author_facet Saito, Masahiro
Saito, Keisuke
Ishikita, Hiroshi
author_sort Saito, Masahiro
collection PubMed
description Manganese (Mn) serves as the catalytic center for water splitting in photosystem II (PSII), despite the abundance of iron (Fe) on earth. As a first step toward why Mn and not Fe is employed by Nature in the water oxidation catalyst, we investigated the Fe(4)CaO(5) cluster in the PSII protein environment using a quantum mechanical/molecular mechanical (QM/MM) approach, assuming an equivalence between Mn(III/IV) and Fe(II/III). Substituting Mn with Fe resulted in the protonation of μ-oxo bridges at sites O2 and O3 by Arg357 and D1-His337, respectively. While the Mn(4)CaO(5) cluster exhibits distinct open- and closed-cubane S(2) conformations, the Fe(4)CaO(5) cluster lacks this variability due to an equal spin distribution over sites Fe1 and Fe4. The absence of a low-barrier H-bond between a ligand water molecule (W1) and D1-Asp61 in the Fe(4)CaO(5) cluster may underlie its incapability for ligand water deprotonation, highlighting the relevance of Mn in natural water splitting.
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spelling pubmed-103829162023-07-30 Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex Saito, Masahiro Saito, Keisuke Ishikita, Hiroshi iScience Article Manganese (Mn) serves as the catalytic center for water splitting in photosystem II (PSII), despite the abundance of iron (Fe) on earth. As a first step toward why Mn and not Fe is employed by Nature in the water oxidation catalyst, we investigated the Fe(4)CaO(5) cluster in the PSII protein environment using a quantum mechanical/molecular mechanical (QM/MM) approach, assuming an equivalence between Mn(III/IV) and Fe(II/III). Substituting Mn with Fe resulted in the protonation of μ-oxo bridges at sites O2 and O3 by Arg357 and D1-His337, respectively. While the Mn(4)CaO(5) cluster exhibits distinct open- and closed-cubane S(2) conformations, the Fe(4)CaO(5) cluster lacks this variability due to an equal spin distribution over sites Fe1 and Fe4. The absence of a low-barrier H-bond between a ligand water molecule (W1) and D1-Asp61 in the Fe(4)CaO(5) cluster may underlie its incapability for ligand water deprotonation, highlighting the relevance of Mn in natural water splitting. Elsevier 2023-07-08 /pmc/articles/PMC10382916/ /pubmed/37520740 http://dx.doi.org/10.1016/j.isci.2023.107352 Text en © 2023 The Authors https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Saito, Masahiro
Saito, Keisuke
Ishikita, Hiroshi
Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex
title Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex
title_full Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex
title_fullStr Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex
title_full_unstemmed Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex
title_short Structural and energetic insights into Mn-to-Fe substitution in the oxygen-evolving complex
title_sort structural and energetic insights into mn-to-fe substitution in the oxygen-evolving complex
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10382916/
https://www.ncbi.nlm.nih.gov/pubmed/37520740
http://dx.doi.org/10.1016/j.isci.2023.107352
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