Kinetic study of transmembrane electron transport by the hinkle process

Trans-membrane redox reactions mediated by t-amylferrocene (one-electron carrier) were studied kinetically in a liposome system separating two redox pairs (ferricyanide/ferrocyanide and dehydroascorbate/ascorbate). In order to eliminate the membrane potential generated, which suppressed the rate of the reaction, the rate was measured in the presence of carbonylcyanide m-chlorophenylhydrazone. The reaction rate was independent of concentrations of ascorbate and dehydroascorbate. Ferricyanide also had virtually no effect on the rate, but addition of ferrocyanide decreased it. The results were analysed on the basis of rate equations derived from the possible reaction mechanism, and it was concluded that the rate-determining step of the trans-membrane redox reaction was the process of diffusion of the mediator in the membrane.