Metabolic Control Analysis of Bioelectrodes for Multistep Oxidation of Biofuels

摘要: Harnessing the biological process of glucose oxidation for the production of electrical energy represents a challenging but highly important goal in bioelectrochemistry. Biological fuels such as glycerol, glucose and sucrose are abundant and possess high energy density. Complete electrochemical oxidation of these fuels at low temperature requires a multistep enzymatic system coupled intimately with carefully tailored electrodes. Tremendous progress has been made recently in creating electrodes based on the krebs cycle, and demonstrating the impact of “closing the loop” on observed power density. However, the efficiency of electrochemical energy conversion is limited compared to living biological systems. There is a need for quantitative understanding of such systems in order to approach systematic design and optimization.An example of such a system is shown in Fig. 1, a version of the Krebs cycle wherein pyruvate is oxidized completely to CO2 by a system of nine enzymes, four of which are NAD (H) dependent enzymes coupled to electrodes. We have developed a kinetic model of this system based on reported experimental results [1], coupled with kinetic parameters for highly active NADH oxidizing electrodes [2]. The model reproduces the observed power density and is suitable for design and optimization purposes.