Matching Items (3)
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- All Subjects: Hydrogen
- Creators: Redding, Kevin
Description
Membrane proteins are a vital part of cellular structure. They are directly involved in many important cellular functions, such as uptake, signaling, respiration, and photosynthesis, among others. Despite their importance, however, less than 500 unique membrane protein structures have been determined to date. This is due to several difficulties with macromolecular crystallography, primarily the difficulty of growing large, well-ordered protein crystals. Since the first proof of concept for femtosecond nanocrystallography showing that diffraction patterns can be collected on extremely small crystals, thus negating the need to grow larger crystals, there have been many exciting advancements in the field. The technique has been proven to show high spatial resolution, thus making it a viable method for structural biology. However, due to the ultrafast nature of the technique, which allows for a lack of radiation damage in imaging, even more interesting experiments are possible, and the first temporal and spatial images of an undamaged structure could be acquired. This concept was denoted as time-resolved femtosecond nanocrystallography.
This dissertation presents on the first time-resolved data set of Photosystem II where structural changes can actually be seen without radiation damage. In order to accomplish this, new crystallization techniques had to be developed so that enough crystals could be made for the liquid jet to deliver a fully hydrated stream of crystals to the high-powered X-ray source. These changes are still in the preliminary stages due to the slightly lower resolution data obtained, but they are still a promising show of the power of this new technique. With further optimization of crystal growth methods and quality, injection technique, and continued development of data analysis software, it is only a matter of time before the ability to make movies of molecules in motion from X-ray diffraction snapshots in time exists. The work presented here is the first step in that process.
This dissertation presents on the first time-resolved data set of Photosystem II where structural changes can actually be seen without radiation damage. In order to accomplish this, new crystallization techniques had to be developed so that enough crystals could be made for the liquid jet to deliver a fully hydrated stream of crystals to the high-powered X-ray source. These changes are still in the preliminary stages due to the slightly lower resolution data obtained, but they are still a promising show of the power of this new technique. With further optimization of crystal growth methods and quality, injection technique, and continued development of data analysis software, it is only a matter of time before the ability to make movies of molecules in motion from X-ray diffraction snapshots in time exists. The work presented here is the first step in that process.
ContributorsKupitz, Christopher (Author) / Fromme, Petra (Thesis advisor) / Spence, John C. (Thesis advisor) / Redding, Kevin (Committee member) / Ros, Alexandra (Committee member) / Arizona State University (Publisher)
Created2014
Description
Hybrid metalloproteins incorporating synthetic organometallic active sites within a protein scaffold are being researched as viable catalysts for the production of hydrogen fuel. Our group and others have shown that the incorporation of cobalt protoporphyrin IX in cytochrome b₅₆₂ yields artificial enzymes that reduce protons to molecular hydrogen in the presence of photoinductive light and photosensitizers. Using random mutagenesis via error-prone PCR we have created a library of mutants to use in directed evolution to optimize hydrogen catalysis, though a challenge in this project is that testing individual variants by gas chromatography is not feasible on a large scale. For this reason, we are developing a gasochromic, hydrogen assay that is based on the interaction of molecular hydrogen with tungsten trioxide with a palladium catalyst. Initially, results show this assay to be qualitatively accurate between trials; however, its application in screening remains a challenge.
ContributorsGutierrez, Elijah (Author) / Ghirlanda, Giovana (Thesis director) / Mills, Jeremy (Committee member) / Redding, Kevin (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor)
Created2022-05
Description
The oxygen sensitivity of hydrogenase is a large barrier in maximizing the efficiency of algal hydrogen production, despite recent efforts aimed at rewiring photosynthesis. This project focuses on the role of photosystem II (PSII) in extended hydrogen production by cells expressing the PSI-HydA1 chimera, with the goal of optimizing continuous production of photobiohydrogen in the green alga, Chlamydomonas reinhardtii. Experiments utilizing an artificial PSII electron
Therefore, it can be concluded that downstream processes are limiting the electron flow to the hydrogenase. It was also shown that the use of a PSII inhibitor, 3-(3,4-dichlorophenyl)-1,1- dimethylurea (DCMU), at sub-saturating concentrations under light exposure during growth temporarily improves the duration of the H2 evolution phase. The maximal hydrogen production rate was found to be approximately 32 nmol h-1 (µg Chl)-1. Although downregulation of PSII activity with DCMU improves the long-term hydrogen production, future experiments must be focused on improving oxygen tolerance of the hydrogenase as a means for higher hydrogen yields.
Therefore, it can be concluded that downstream processes are limiting the electron flow to the hydrogenase. It was also shown that the use of a PSII inhibitor, 3-(3,4-dichlorophenyl)-1,1- dimethylurea (DCMU), at sub-saturating concentrations under light exposure during growth temporarily improves the duration of the H2 evolution phase. The maximal hydrogen production rate was found to be approximately 32 nmol h-1 (µg Chl)-1. Although downregulation of PSII activity with DCMU improves the long-term hydrogen production, future experiments must be focused on improving oxygen tolerance of the hydrogenase as a means for higher hydrogen yields.
ContributorsO'Boyle, Taryn Reilly (Author) / Redding, Kevin (Thesis director) / Ghirlanda, Giovanna (Committee member) / Vermaas, Willem (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / School of Life Sciences (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05