Gated Electron Transfer: Direct Correlation with Redox Protein Dynamics

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry Program supports research by Professor Bruce E. Bowler at the University of Denver to investigate fundamental aspects of gated electron transfer reactions in proteins, which regulate electron flow in metabolic pathways. The research capitalizes on variants of the electron transport protein, iso-1-cytochrome c which are used to vary the reduction potential of the iron site. Electron transfer rates in the modified proteins will be measured by pH jump stopped-flow methods. The thermodynamics and temperature-dependent kinetics of the gating reaction will be measured for all variants. Temperature-dependent kinetics for the electron transfer reactions of the iso-1-cytochrome c variants with small inorganic complexes will be monitored by stopped-flow methods under pseudo first order conditions. By increasing the concentration of the inorganic redox reagent, the observed electron transfer rates will be varied smoothly from non-gating to gating conditions. By comparing the activation parameters and rate constants for ET under gating conditions with those for the gating process, direct correlation of gated ET with a conformational gating reaction will be accomplished. Protein conformational changes linked to changes in the oxidation state of the protein play key roles in gating electron transfer properties in a wide range of important proteins, such as those in the ATP-producing electron transfer chain. Results learned in this study can also be applied to gating currents in biotechnological electronic devices. This research will also train students at various levels, with an emphasis on undergraduate women and underrepresented minority students.