Full metadata
Title
Engineering oxidoreductases: towards artificial hydrogenases
Description
Natural hydrogenases catalyze the reduction of protons to molecular hydrogen reversibly under mild conditions; these enzymes have an unusual active site architecture, in which a diiron site is connected to a cubane type [4Fe-4S] cluster. Due to the relevance of this reaction to energy production, and in particular to sustainable fuel production, there have been substantial amount of research focused on developing biomimetic organometallic models. However, most of these organometallic complexes cannot revisit the structural and functional fine-tuning provided by the protein matrix as seen in the natural enzyme. The goal of this thesis is to build a protein based functional mimic of [Fe-Fe] hydrogenases. I used a 'retrosynthetic' approach that separates out two functional aspects of the natural enzyme. First, I built an artificial electron transfer domain by engineering two [4Fe-4S] cluster binding sites into an existing protein, DSD, which is a de novo designed domain swapped dimer. The resulting protein, DSD-bis[4Fe-4S], contains two clusters at a distance of 36 Å . I then varied distance between two clusters using vertical translation along the axis of the coiled coil; the resulting protein demonstrates efficient electron transfer to/from redox sites. Second, I built simple, functional artificial hydrogenases by using an artificial amino acid comprising a 1,3 dithiol moiety to anchor a biomimetic [Fe-Fe] active site within the protein scaffold Correct incorporation of the cluster into a model helical peptide was verified by UV-Vis, FTIR, ESI-MS and CD spectroscopy. This synthetic strategy is extended to the de novo design of more complex protein architectures, four-helix bundles that host the di-iron cluster within the hydrophobic core. In a separate approach, I developed a generalizable strategy to introduce organometallic catalytic sites into a protein scaffold. I introduced a biomimetic organometallic complex for proton reduction by covalent conjugation to biotin. The streptavidin-bound complex is significantly more efficient in photocatalytic hydrogen production than the catalyst alone. With these artificial proteins, it will be possible to explore the effect of second sphere interactions on the activity of the diiron center, and to include in the design properties such as compatibility with conductive materials and electrodes.
Date Created
2014
Contributors
- Roy, Anindya (Author)
- Ghirlanda, Giovanna (Thesis advisor)
- Yan, Hao (Committee member)
- Gust, Devens (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
xv, 169 p. : col. ill
Language
eng
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.I.25166
Statement of Responsibility
by Anindya Roy
Description Source
Retrieved on Aug. 19, 2014
Level of coding
full
Note
thesis
Partial requirement for: Ph.D., Arizona State University, 2014
bibliography
Includes bibliographical references
Field of study: Chemistry
System Created
- 2014-06-09 02:19:46
System Modified
- 2021-08-30 01:33:49
- 3 years 2 months ago
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