Tuning Redox Potentials of Metal Centers in a Single Protein

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The Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Yi Lu of University of Illinois at Urbana-Champaign to study the dependence of the redox potential of metal centers in proteins on the secondary coordination sphere of the metal center. This effort is important because the redox potential of proteins is a property at the heart of many chemical and biological processes, ranging from electron transfer in photosynthesis and respiration, to catalysis in fuel cells and nitrogen fixation. Despite the importance of redox potentials, a comprehensive and systematic understanding of factors that control the redox potentials of the proteins, particularly those factors that do not perturb the primary coordination sphere of the metal centers, remains elusive. This project will contribute to filling this knowledge gap; the new knowledge will be applied in addressing interesting problems in chemistry and biology. The interdisciplinary research will be a ground for the sound training of students. The results of the research will be integrated in new and existing courses and in presentations to a broad range of audiences. This research project will advance the fundamental understanding of the factors that affect the redox potential of metal centers in proteins. The new understanding will be applied in the synthesis of new water-soluble, stable redox agents for biochemical studies, which in turn will be used to study the transfer of electrons in the inverted regime of Marcus theory, and of biocatalysts whose activity is tuned by changes in their redox potential. The methods by which the redox potential will be rationally modified include point mutation directed exclusively to the second-coordination sphere of the metal, use of non-natural amino acids to change the steric and electronic properties of the metal site in ways not possible using natural amino acids, and protein directed evolution to afford the fast exploration of a relatively large sequence space.