Unusual Properties of the Nitrous oxide reductase: Mitigation of N₂O (green house gas)

Nitrous oxide (N2O) is a powerful greenhouse gas that contributes to global warming. One way to mitigate its impact is through the use of nitrous oxide reductase (N2OR), an enzyme that converts N2O into nitrogen gas. N2OR is found in certain bacteria and is composed of a copper cluster, which plays a critical role in its catalytic activity. In this study, we investigate the potential of utilizing N2OR and copper clusters as a means of reducing N2O emissions. We explore different methods for producing N2OR and copper clusters, as well as their effectiveness in converting N2O to nitrogen gas. The microbial denitrification pathway accounts for the dissimilatory transformation of nitrate and nitrite, in four reactions catalyzed by different metalloenzymes, that sequentially convert nitrate into dinitrogen (with nitrite, nitric oxide and N2O as intermediates). In this talk we will address the structure/function relationship of the N2Or that reduces N2O, using a toolbox of spectroscopic, kinetic, electrochemical and structural techniques aiming to better understand the enzyme to enhance its N2O mitigation potential. Marinobacter hydrocarbonoclasticus N2OR contains two copper centers, CuA, the electron transfer site, and an additional "CuZ", the catalytic center. "CuZ" is a unique center in biological systems, since it has a sulfide bridging ligand bound to a distorted tetrahedron of copper ions, also coordinated by seven histidine side chains. In this presentation the different forms of the catalytic cluster are spectroscopic characterized, a proton-electron coupled process is shown to occur and the involvement of the different forms in a new catalytic cycle is proposed and discussed.