2021/05/26 by Muhamed Amin, Amin, Muhamed, Divya Kaur +5
Biochemistry, Genetics and Molecular Biology · Neuroscience · Physics and Astronomy · #Biological Physics (physics.bio-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Photoreceptor and optogenetics research #Photosynthetic Processes and Mechanisms #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.2105.12387
openalex publication_date 2021/05/26 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
Understanding the water oxidation mechanism in Photosystem II (PSII)\nstimulates the design of biomimetic artificial systems that can convert solar\nenergy into hydrogen fuel efficiently. The Sr2+ substituted PSII is active but\nslower than with the native Ca2+ as an oxygen evolving catalyst. Here, we use\nDensity Functional Theory (DFT) to compare the energetics of the S2 to S3\ntransition in the Mn4O5Ca2+ and Mn4O5Sr2+ clusters. The calculations show that\ndeprotonation of the water bound to Ca2+ (W3), required for the S2 to S3\ntransition, is energetically more favorable in Mn4O5Ca2+ than Mn4O5Sr2+. In\naddition, we have calculated the pKa of the water that bridges Mn4 and the\nCa2+/Sr2+ in the S2 using continuum electrostatics. The calculations show that\nthe pKa is higher by 4 pH units in the Mn4O5Sr2+.\n