Akif Tezcan

Bioinorganic and biophysical chemistry: Metalloprotein structure, function and biosynthesis

The projects in the Tezcan group focus on the elucidation of metal-catalyzed biological redox reactions, and the control of biological processes through coordination chemistry.

Understanding Biological Nitrogen Fixation
There are few reactions in nature that can simultaneously match the global importance, socioeconomic impact, biological complexity and chemical challenge of nitrogen fixation. The conversion of molecular nitrogen (N2) into bioavailable forms such as ammonia (NH3) is essential for the biosynthesis of amino and nucleic acids, as well as the production of fertilizers and countless industrial chemicals. The extreme conditions required by the industrial nitrogen fixation processes, however, translate into an immense dependence on fossil fuels and account for >1% of all human energy consumption. This energy demand, coupled with dwindling fuel supplies and rapid rise in greenhouse gas emissions, makes it an absolute necessity to seek clean and efficient means for NH3 production. Our goal towards this end is to elucidate the molecular mechanism of nitrogenase, a redox-metalloenzyme that catalyzes N2-fixation at ambient conditions.

What sets nitrogenase apart from most biological redox systems is its requirement of 16 ATP molecules for a single catalytic turnover reaction despite a favorable driving force. In separate but connected projects, we aim 1) to understand why and how ATP-hydrolysis is involved in nitrogen fixation, and 2) to drive the nitrogenase reaction by using light or electrochemical energy instead of ATP hydrolysis in order to achieve a better control and understanding of N2-activation. Tackling this complex system requires a multi-disciplinary effort. Towards this end, we utilize a diverse array of tools, ranging from chemical synthesis, molecular biology and anaerobic protein biochemistry to X-ray crystallography, fluorescence spectroscopy, electrochemistry and photochemistry.

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