A Universal Mechanism for N2 Binding to and Differing Reactivity of the E4(4H) State of Mo-, V-, and Fe-Nitrogenases

As a basic building block in many biological molecules, the element nitrogen (N) is essential for life. Dinitrogen (N2) is abundant in Earth’s atmosphere, but this form is biologically unavailable. To be biologically available, N2 must undergo a reduction reaction to the fixed form, ammonia (NH3). The industrial Haber-Bosch process, which accounts for approximately 50% of the worlds fixed nitrogen, uses energy from fossil fuels to achieve high pressures and temperatures to catalyze the reaction. The energy used by Haber-Bosch accounts for approximately 2% of the world’s annual supply. The remainder of fixed nitrogen is produced biologically by nitrogen fixing microorganisms (diazotrophs), utilizing nitrogenase enzymes. Nitrogenase enzymes catalyze the reduction at ambient temperature and pressure, deriving the necessary energy from the energy rich molecule adenosine triphosphate (ATP). The focus of this dissertation is enriching our understanding of how nitrogenase enzymes can catalyze this crucial reaction under ambient conditions. This, of course, leads to a better understanding of biological nitrogen fixation, but also reveals the strategies that nature has evolved which can inform on the development of cleaner more efficient industrial processes