Diode or Tunnel-Diode Characteristics? Resolving the Catalytic Consequences of Proton Coupled Electron Transfer in a Multi-Centered Oxidoreductase

摘要: Protein film voltammetry has been employed to define multiple catalytic consequences of proton coupled electron transfer (PCET) in a cytochrome c nitrite reductase. Current-potential profiles reflecting the steady-state rate nitrite-limited reduction have defined from pH 4 8. Lowering electrode potential at 8 causes current increase and then decrease before it takes value independent any further lowering potential. By comparison, 4, catalysis is initiated more positive potentials an approximately sigmoidal fashion with no attenuation evident negative potentials. The results show that activity turned on by two electrons one enzyme. decreased lower under alkaline conditions shows this occurs only when not compensating protonation(s) Sites within enzyme whose and/or protonation may contribute definition these activities are discussed.