Date of Award

2014

Degree Name

Chemistry

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Derrick Kolling

Second Advisor

Scott Day

Third Advisor

Bin Wang

Abstract

Photosystem II (PSII) research has gained interest in recent years due to the need for energy production. However the mechanisms of photosystem II photoassembly and water oxidation are not well understood. Therefore the main goal of my research was to understand photoassembly better by determining the pH dependence of oxygen evolving complex (OEC) assembly. These experiments could help to gain a better understanding of D1 (a subunit of photosystem II) degradation and PSII repair as well as determine the amino acid residues involved in the process. However, we had several issues with photoassembly along the way that had to be addressed in order to perform this experiment. Therefore, we first had to optimize the process for depleting the cofactors from PSII (known as apo-BBY (PSII enriched particles) preparation) and photoassembly of PSII. This process took up most of my time in the lab so the pH dependence experiment was not fully completed and conclusions cannot be made based on the data we got. A side project included in this research, due to the issues we had, was to understand the temperature dependence of water oxidation. These experiments revealed that calcium chloride can increase the rate of oxygen evolution when a redox mediator is absent and also the maximum activity for chloroplasts is found at a higher temperature than for isolated PSII. A second side project was to study non-conventional redox mediators in order to enhance the rate of oxygen-evolution. The results showed a decrease in oxygen evolution with carbon nanotubes and gold nanoparticles. The combined data from all the experiments we performed will lead to a better understanding of photosystem II as well as lead to better ways of studying photosystem II.

Subject(s)

Photosynthesis

Photochemistry

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