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

OnderzoeksoutputAcademicpeer review

18 Citaten (Scopus)


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.
Originele taal-2English
Pagina's (van-tot)4243-4248
Aantal pagina's6
TijdschriftThe Journal of Physical Chemistry B
Nummer van het tijdschrift18
StatusPublished - 12-mei-2016
Extern gepubliceerdJa

Citeer dit