Date of Award

2013

Degree Type

Thesis

Department

Chemistry

First Advisor

Bayachou, Mekki

Subject Headings

Electrochemistry, Nitric-oxide synthase, Nitroalkanes

Abstract

Organic nitroalkanes are used in many industries and for a variety of purposes. Their use is expanding and is steadily claiming new territories in our immediate environment. Some nitroalkanes, when they enter the human body, can be harmful as such or can be activated to generate reactive intermediates with known detrimental effects. P450 enzymes are known for metabolizing a variety of drugs and substances including organic nitroalkanes. Nitric oxide synthases (NOS) exhibit some similarities to P450 metalloenzymes and their potential interaction with nitroalkanes as xenobiotics is not well known. The present study investigates the effect of nitroalkanes on the catalytic reaction of NOS in light of the NOS-mediated catalytic reduction of the same nitroalkanes. In this work, we used the recombinant oxygenase domain of inducible nitric oxide synthase (iNOSoxy) and endothelial nitric oxide synthase (eNOSoxy). We have previously shown that the oxygenase domain of nitric oxide synthases (NOSs) in thin surfactant films can exchange electrons with the underlying electrode. We show in the current work that NOS oxygenase domains act as efficient electrocatalysts for nitroalkane reductions in surfactant films on pyrolytic graphite electrodes. We monitored the NOSoxy-mediated catalytic reduction of a series of nitroalkanes using electrochemical techniques. Concomitantly, we used chemical assays such as the Griess assay to assess enzymatic activity of NOSoxys under the same conditions. Voltammograms at different concentrations of nitroalkanes and different scan rates were used to derive catalytic parameters such as catalytic efficiency, Km and kcat values for NOSoxy-mediated catalytic reduction of nitroalkanes. Overall, we present a comparative study of the electroreduction of nitromethane, nitroethane, and nitropropane using eNOSoxy and iNOSoxy as electrocatalysts. We also compare and contrast how -and the extent to which- each nitroalkane affects the catalytic NOS reaction by iNOSoxy and eNOSoxy

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Chemistry Commons

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