The effect of the phase transition of a bilayer membrane on the electrochemical behavior of ferredoxin embedded in a cast film of artificial lipid, 2C18N+Br-, was investigated. The redox potential of ferredoxin embedded in the lipid film showed a linear, positive shift from -510 (±2) to -466 (±3) mV (vs. Ag|AgCl| saturated KCl) with increasing temperature from 25 to 53 °C. The diffusion coefficient (D) and heterogeneous electron transfer rate constant (ko′) were evaluated at various temperatures by means of analyzing cyclic voltammograms. The overall shape of the simulated voltammograms fitted well with the experimentally observed voltammograms at various potential sweep rates, when the estimated D and ko′ values were used for the simulation. The results of the temperature dependence of the estimated D and k o′ values indicated that D and ko′ were enhanced near the phase transition temperature (Tc), 46 °C, of the lipid film. The D and ko′ values at temperatures above the Tc were approximately two-orders and one-order of magnitude larger than those estimated at temperatures under the Tc, respectively. The estimated D and ko′ values were 2.1-5.8 × 10 -10 cm2 s-1 and 1.2-1.6 × 10 -4 cm s-1 at 25 °C, and 3.5-3.7 × 10 -8 cm2 s-1 and 1.1-1.2 × 10-3 s-1 at 50 °C, respectively. The electrochemical behavior of ferredoxin in the lipid film changed drastically near the Tc.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Chemical Engineering(all)