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Metalloenzymes and metal-containing biomolecules play crucial roles in the global N-cycle. Many of these biomolecules contain the redox-active Fe metal that binds to various inorganic NOx and related organo-NOx compounds to mediate their chemical conversions.  Such conversions have consequences in the atmosphere and in our natural environment including impacting N-assimilation in agriculture. These conversions also have critical roles in human physiology.  We have developed collaborations in advanced DFT calculations (Zhang and Shao) to help guide our work.

NOx Bioinorganic Chemistry

The Fe porphyrin unit (heme) is a ubiquitous cofactor in many metalloenzymes and biomolecules. We determine the factors that promote binding and activation of NOx species such as NO, nitrite, and organo-NOx compounds by the redox-active (por)Fe unit. Such processes are critical for the environmentally relevant N-N bond formation step carried out by bacteria and fungi to generate the greenhouse gas nitrous oxide (N2O).

Electrochemistry and Spectroelectrochemistry

Electrochemistry is an excellent tool to study the generation and behavior of redox intermediates in chemical reactions.  In an NSF-sponsored project, we collaborate with Michael Shaw at SIUE in advanced non-aqueous electrochemical techniques and IR/UV-vis spectroelectrochemistry to probe the redox behavior of our new heme model-NOx compounds and intermediates.

Structural Biology of Heme Proteins

We utilize macromolecular X-ray diffraction, working primarily with the blood protein hemoglobin (Hb) and the muscle protein myoglobin (Mb), to elucidate the role that Fe plays in the physiological chemistry of NOx species such as NO, nitrite, nitrosoamphetamine, and other organo-NOx compounds derived from drugs.