Toward understanding the S2-S3 transition in the Kok cycle of Photosystem II: Lessons from Sr-substituted structure

Muhamed Amin*, Divya Kaur, M. R. Gunner, Gary W. Brudvig

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

3 Citaten (Scopus)
31 Downloads (Pure)


Understanding the water oxidation mechanism in Photosystem II (PSII) stimulates the design of biomimetic artificial systems that can convert solar energy into hydrogen fuel efficiently. The Sr2+-substituted PSII is active but slower than with the native Ca2+ containing PSII as an oxygen evolving catalyst. Here, we use Density Functional Theory (DFT) to compare the energetics of the S2 to S3 transition in the Mn4O5Ca2+ and Mn4O5Sr2+ clusters. The calculations show that deprotonation of the water bound to Ca2+ (W3), required for the S2 to S3 transition, is energetically more favorable in Mn4O5Ca2+ than Mn4O5Sr2+. In addition, we have calculated the pKa of the water that bridges Mn4 and the Ca2+/Sr2+ in the S2 state using continuum electrostatics. The calculations show that the pKa is higher by 4 pH units in the Mn4O5Sr2+cluster.
Originele taal-2English
Aantal pagina's4
TijdschriftInorganic Chemistry Communications
Vroegere onlinedatum1-sep-2021
StatusPublished - nov-2021

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