Nitrogen (N) is a chemical constituent for almost all biological molecules including proteins, DNA, RNA, lipids and is therefore vital for life. The ultimate source of nitrogen is the atmospheric dinitrogen (N2) but that only becomes bioavailable through a process of nitrogen fixation, the process that converts N2 to ammonia (NH3). The industrial Haber-Bosch process and biological nitrogen fixation account for the majority of nitrogen fixed every year. However, due to its high temperature, pressure and fossil fuel requirements, Haber-Bosch is an expensive process. Every year, approximately 3% of the global energy demand is used to manufacture ammonia through Haber-Bosch process. On the other hand, biological systems produce ammonia by reducing dinitrogen at ambient temperature and pressure using an anaerobic enzyme called nitrogenase. Research in understanding the mechanism of nitrogenase could eventually allow researchers to mimic the enzyme and fix nitrogen efficiently at standard temperature and pressure.
In this research nitrogenase of Azotobacter vinelandii was studied to understand the mechanism of delivery of electrons/protons to the active site and how these accumulated reducing equivalents are used for substrates reduction. Through a series of studies, it has been demonstrated that the electrons and protons are added to the active site in a concerted manner which are then stored as bridging hydrides. The accumulated hydrides are used in four different mechanisms, namely reductive elimination, hydride protonolysis, migratory insertion and proton coupled electron transfer, to catalyze the reduction of varieties of unsaturated molecules. This fundamental understanding of molecular detail of nitrogenase catalysis could eventually help in development of more efficient, robust and selective catalysts.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-6676 |
| Date | 01 May 2017 |
| Creators | Khadka, Nimesh |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
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