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Description
Redox enzymes represent a big group of proteins and they serve as catalysts for
biological processes that involve electron transfer. These proteins contain a redox center
that determines their functional properties, and hence, altering this center or incorporating
non-biological redox cofactor to proteins has been used as a means to generate redox
proteins with desirable activities for biological and chemical applications. Porphyrins and
Fe-S clusters are among the most common cofactors that biology employs for electron
transfer processes and there have been many studies on potential activities that they offer
in redox reactions.
In this dissertation, redox activity of Fe-S clusters and catalytic activity of porphyrins
have been explored with regard to protein scaffolds. In the first part, modular property of
repeat proteins along with previously established protein design principles have been
used to incorporate multiple Fe-S clusters within the repeat protein scaffold. This study is
the first example of exploiting a single scaffold to assemble a determined number of
clusters. In exploring the catalytic activity of transmetallated porphyrins, a cobalt-porphyrin
binding protein known as cytochrome c was employed in a water oxidation
photoelectrochemical cell. This system can be further coupled to a hydrogen production
electrode to achieve a full water splitting tandem cell. Finally, a cobalt-porphyrin binding
protein known as cytochrome b562 was employed to design a whole cell catalysis system,
and the activity of the surface-displayed protein for hydrogen production was explored
photochemically. This system can further be expanded for directed evolution studies and
high-throughput screening.
biological processes that involve electron transfer. These proteins contain a redox center
that determines their functional properties, and hence, altering this center or incorporating
non-biological redox cofactor to proteins has been used as a means to generate redox
proteins with desirable activities for biological and chemical applications. Porphyrins and
Fe-S clusters are among the most common cofactors that biology employs for electron
transfer processes and there have been many studies on potential activities that they offer
in redox reactions.
In this dissertation, redox activity of Fe-S clusters and catalytic activity of porphyrins
have been explored with regard to protein scaffolds. In the first part, modular property of
repeat proteins along with previously established protein design principles have been
used to incorporate multiple Fe-S clusters within the repeat protein scaffold. This study is
the first example of exploiting a single scaffold to assemble a determined number of
clusters. In exploring the catalytic activity of transmetallated porphyrins, a cobalt-porphyrin
binding protein known as cytochrome c was employed in a water oxidation
photoelectrochemical cell. This system can be further coupled to a hydrogen production
electrode to achieve a full water splitting tandem cell. Finally, a cobalt-porphyrin binding
protein known as cytochrome b562 was employed to design a whole cell catalysis system,
and the activity of the surface-displayed protein for hydrogen production was explored
photochemically. This system can further be expanded for directed evolution studies and
high-throughput screening.
ContributorsBahrami Dizicheh, Zahra (Author) / Ghirlanda, Giovanna (Thesis advisor) / Allen, James P. (Committee member) / Seo, Dong Kyun (Committee member) / Arizona State University (Publisher)
Created2019