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Title: Broken symmetry density functional theory studies of multinuclear manganese metalloproteins
Author: Beal, Nathan James
ISNI:       0000 0004 6425 590X
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2017
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The photosynthetic water splitting reaction performed in green plants, algae and cyanobacteria is perhaps one of the most important reactions on the planet. The reaction is catalysed by a tetranuclear manganese cluster that is driven by sunlight and as such has received a high degree of interest in the context of solar fuels research. Due to the intricacy of the bioinorganic systems, the molecular mechanisms of the reactions are unknown and structural elucidation of the active sites is complicated. Computational techniques can provide considerable support in the analysis and interpretation of the complex EPR spectra of such biological systems. In this work, the molecular and electronic structures of several multinuclear manganese containing bioinorganic systems are investigated using BS-DFT. A particular focus of this work is the provision of high quality calculated EPR parameters yielding structural and mechanistic insight. In the first results chapter, the MnIIIMnIV superoxidised state of manganese catalase as well as azide inhibited manganese catalase is studied. Several variants are proposed and analysed on the basis of their calculated EPR parameters. The results presented in this chapter offer a new interpretation of previous experimental assignments. Chapter 6 features investigations on the S2 state of the Oxygen Evolving Complex of Photosystem II. In this chapter both the native OEC as well as the strontium substituted OEC are studied, in order to investigate how replacement of the calcium ion affects the structure of the OEC. The final results chapter presents calculations on the split signal S2Yz dot radical formed on the transition from the S2 to S3 state, as well as studying the S3 state. The calculation of various EPR hyperfine couplings and their comparison with available experimental data has provided key insights into the electronic structure of the OEC.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Density Functional Theory ; BS-DFT ; PSII ; OEC ; EPR Calculations ; Manganese Catalase