Date of Award
Chemistry and Biochemistry
The continued burning of fossil fuels is not only a cause of increasing deterioration of the environment but also a financially unsustainable source of energy. Advances in energy production must be investigated to avoid the long-term effects of this current main source of energy. One of the avenues being explored is the use of metalloenzymes to catalyze hydrogen evolution via water splitting that occurs during the reductive half of artificial photosynthesis. Metalloenzyme catalysts with a single Ni(Cys)4 active site have been previously studied, and this study explores the possibility of increasing hydrogen production by using metalloenzyme catalysts with multiple Ni(Cys)4 active sites. The protein α-metallothionein and 4 de novo designed mutants of this protein are synthesized and purified before being anaerobically bound to the metal nickel. A photosensitizer and an electron donor are added to Ni3-αMT and the 4 Ni1-αMT mutants, respectively, and the samples are dissolved in a buffer. Hydrogen gas is produced by the solutions when they are irradiated with white light. The production is quantified using gas chromatography, and the results of this study suggest that multi-metallic active sites are positively correlated with photocatalytic hydrogen evolution. The strength of Ni-Cys coordination in different clusters in the αMT sequence is also observed through comparison of the 4 mutants.
Swetman, Windfield, "Photocatalyzed Hydrogen Evolution Using Nickel-Bound Metallothionein Protein" (2023). Honors Theses. 2917.
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