Effect of Chloride Depletion on the Magnetic Properties and the Redox Leveling of the Oxygen-Evolving Complex in Photosystem II

Muhamed Amin; Ravi Pokhrel; Gary W Brudvig; Ashraf Badawi; S. S A Obayya

doi:10.1021/acs.jpcb.6b03545

Effect of Chloride Depletion on the Magnetic Properties and the Redox Leveling of the Oxygen-Evolving Complex in Photosystem II

Muhamed Amin, Ravi Pokhrel, Gary W Brudvig, Ashraf Badawi, S. S A Obayya

Yale University

Research output: Contribution to journal › Article › peer-review

17 Citations (Scopus)

Abstract

Chloride is an essential cofactor in the oxygen-evolution reaction that takes place in photosystem II (PSII). The oxygen-evolving complex (OEC) is oxidized in a linear four-step photocatalytic cycle in which chloride is required for the OEC to advance beyond the S₂ state. Here, using density functional theory, we compare the energetics and spin configuration of two different states of the Mn₄CaO₅ cluster in the S₂ state: state A with Mn1³⁺ and B with Mn4³⁺ with and without chloride. The calculations suggest that model B with an S = 5/2 ground state occurs in the chloride-depleted PSII, which may explain the presence of the EPR signal at g = 4.1. Moreover, we use multiconformer continuum electrostatics to study the effect of chloride depletion on the redox potential associated with the S₁/S₂ and S₂/S₃ transitions.

Original language	English
Pages (from-to)	4243-4248
Number of pages	6
Journal	Journal of Physical Chemistry B
Volume	120
Issue number	18
DOIs	https://doi.org/10.1021/acs.jpcb.6b03545
Publication status	Published - May 12 2016

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Materials Chemistry
Surfaces, Coatings and Films

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title = "Effect of Chloride Depletion on the Magnetic Properties and the Redox Leveling of the Oxygen-Evolving Complex in Photosystem II",

abstract = "Chloride is an essential cofactor in the oxygen-evolution reaction that takes place in photosystem II (PSII). The oxygen-evolving complex (OEC) is oxidized in a linear four-step photocatalytic cycle in which chloride is required for the OEC to advance beyond the S2 state. Here, using density functional theory, we compare the energetics and spin configuration of two different states of the Mn4CaO5 cluster in the S2 state: state A with Mn13+ and B with Mn43+ with and without chloride. The calculations suggest that model B with an S = 5/2 ground state occurs in the chloride-depleted PSII, which may explain the presence of the EPR signal at g = 4.1. Moreover, we use multiconformer continuum electrostatics to study the effect of chloride depletion on the redox potential associated with the S1/S2 and S2/S3 transitions.",

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T1 - Effect of Chloride Depletion on the Magnetic Properties and the Redox Leveling of the Oxygen-Evolving Complex in Photosystem II

AU - Amin, Muhamed

AU - Pokhrel, Ravi

AU - Brudvig, Gary W

AU - Badawi, Ashraf

AU - Obayya, S. S A

PY - 2016/5/12

Y1 - 2016/5/12

N2 - Chloride is an essential cofactor in the oxygen-evolution reaction that takes place in photosystem II (PSII). The oxygen-evolving complex (OEC) is oxidized in a linear four-step photocatalytic cycle in which chloride is required for the OEC to advance beyond the S2 state. Here, using density functional theory, we compare the energetics and spin configuration of two different states of the Mn4CaO5 cluster in the S2 state: state A with Mn13+ and B with Mn43+ with and without chloride. The calculations suggest that model B with an S = 5/2 ground state occurs in the chloride-depleted PSII, which may explain the presence of the EPR signal at g = 4.1. Moreover, we use multiconformer continuum electrostatics to study the effect of chloride depletion on the redox potential associated with the S1/S2 and S2/S3 transitions.

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