Approach to artificial mitochondria and highly functional artificial organ devices

The coupled reactions of the cytochrome-C(Cyt-C)-immobilized electrode and oxidoreductase, e.g. cytochrome oxidase and diachorase, were examined using horse heart mitochondrial Cyt. C. Diaphorase from Bacillus stearothermophilus was coated on In₂O₃/SnO₂ (ITO) electrodes. The polymer-coated electrodes were applied to Cyt. C phosphate-buffered solution (pH 7.4) for cyclic voltammetric analysis. The electron transfer of the immobilized Cyt. C turned out to be ionically controlled. Biochemical assays of immobilized Cyt. C with cytochrome oxidase indicated that apparent cathodic currents of Cyt. C decrease with ionic strength (IS), but that cathodic current per molecule decrease with IS. The electron transfer activity of an immobilized Cyt. C molecule is found to be closely correlated to apparent diffusion constant. The phenomenon suggests that fixed Cyt. C should have adequate rotary freedoml for electron transfer in mitochondrial inner membrane. Cyt. C loosely immobilized on the coated In₂O₃/SnO ₂ electrode also reacted with diachorase. Because the redox reaction of immobilized Cyt. C could be regulated by the electrode potential, it is though that electrochemical NADH oxidation results from mediation of immobilized Cyt. C. An optimal condition was examined for this coupling reaction