Data on the manganese cluster's oxidation state via photoactivation of photosystem II microcrystals
type: Dataset
description: Knowledge of the manganese oxidation states of the oxygen-evolving Mn4CaO5 cluster in photosystem II (PSII) is crucial toward understanding the mechanism of biological water oxidation. There is a 4 decade long debate on this topic that historically originates from the observation of a multiline electron paramagnetic resonance (EPR) signal with effective total spin of S = 1/2 in the singly oxidized S2 state of this cluster. This signal implies an overall oxidation state of either Mn(III)3Mn(IV) or Mn(III)Mn(IV)3 for the S2 state. These 2 competing assignments are commonly known as "low oxidation (LO)" and "high oxidation (HO)" models of the Mn4CaO5 cluster. Recent advanced EPR and Mn K-edge X-ray spectroscopy studies converge upon the HO model. However, doubts about these assignments have been voiced, fueled especially by studies counting the number of flash-driven electron removals required for the assembly of an active Mn4CaO5 cluster starting from Mn(II) and Mn-free PSII. This process, known as photoactivation, appeared to support the LO model since the first oxygen is reported to evolve already after 7 flashes. In this study, we improved the quantum yield and sensitivity of the photoactivation experiment by employing PSII microcrystals that retained all protein subunits after complete manganese removal and by oxygen detection via a custom built thin-layer cell connected to a membrane inlet mass spectrometer. We demonstrate that 9 flashes by a nanosecond laser are required for the production of the first oxygen, which proves that the HO model provides the correct description of the Mn4CaO5 cluster's oxidation states. The dataset was originally published in DiVA and moved to SND in 2024.
citation: CreativeWork
  name: Cheah MH, Zhang M, Shevela D, Mamedov F, Zouni A, Messinger J. Assessment of the manganese cluster's oxidation state via photoactivation of photosystem II microcrystals. Proc Natl Acad Sci U S A. 2020 Jan 7;117(1):141-145. doi: 10.1073/pnas.1915879117. Epub 2019 Dec 17. PMID: 31848244; PMCID: PMC6955365.
conditions of access: http://publications.europa.eu/resource/authority/access-right/PUBLIC
conditions of access: info:eu-repo/semantics/openAccess
creative work status: completed
  type: DefinedTerm
  in defined term set: http://publications.europa.eu/resource/authority/dataset-status
  term code: COMPLETED
creator: Mun Hon Cheah
  type: Person
  affiliation: Uppsala University
  family name: Cheah
  given name: Mun Hon
date modified: 2024-08-22
date published: 2019-11-07
language: English
is part of: https://doi.org/10.57804/2gkx-sq83
keywords: Physical Chemistry
  type: DefinedTerm
  description: Including: Surface- and Colloid Chemistry
  term code: 10402
keywords: chemical reactions
keywords: manganese
publisher: Uppsala University
distribution: data/DATASET01.txt
  type: DataDownload
  additional type: data
  conditions of access: http://publications.europa.eu/resource/authority/access-right/PUBLIC
  conditions of access: info:eu-repo/semantics/openAccess
  content size: 2218074
  encoding format: text/plain
version: 1

PropertyValue
property ID: DOI
value: 10.57804/j2cm-4298

PropertyValue
property ID: URN
value: urn:nbn:se:uu:diva-396689

PropertyValue
property ID: DOI
value: 10.1073/pnas.1915879117

Uppsala University
type: Organization

English
type: Language
alternate name: eng

chemical reactions
type: DefinedTerm
term code: p3658

manganese
type: DefinedTerm
term code: p1635