Elucidating the Reactivity of Cytochrome P460: Maturation, Product Selectivity, and Substrate Scope

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Ammonia oxidizing bacteria (AOB) have evolved a nitrogen-based metabolism in which they rely solely on the oxidation of ammonia as their energy for life. In contrast to carbon-based metabolisms, there is a large gap in our knowledge of nitrogen-based metabolisms. The primary energy producing step by AOB is performed by the enzyme hydroxylamine oxidoreductase, which oxidizes hydroxylamine (NH2OH) to nitric oxide (NO). Another enzyme expressed by AOB, cytochrome P460, can also oxidize NH2OH but produces nitrous oxide (N2O). The ability of these enzymes to oxidize NH2OH is attributed in part to their unique heme P460 cofactors, which feature additional cross-links to the porphyrin. While a proposed function of cytochrome P460 in vivo is the detoxification of NH2OH, this remains speculative. This thesis will address the reactivity of cytochrome P460 and put it into the context of AOB metabolism. Cytochrome P460 can catalyze a variety of reactions, both as the proenzyme and matured cross-linked enzyme. I will interrogate the mechanisms employed by cytochrome P460 using a combination of spectroscopy and mutagenesis. By doing so, I hope to expand our understanding of the function(s) of cytochrome P460, highlighting its ability to do chemistry that had not previously been considered. The results herein will have important implications for AOB metabolism.

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247 pages


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Bioinorganic; Cytochrome P460; Hydroxylamine Oxidation; Nitrification; Spectroscopy


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Union Local


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Lancaster, Kyle

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Crane, Brian
Ando, Nozomi

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Chemistry and Chemical Biology

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Ph. D., Chemistry and Chemical Biology

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Doctor of Philosophy

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Government Document




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dissertation or thesis

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