Performance of metabolic pathway biomimetic reactors. II. Electrode transport studies

The biosynthesis of lactate from pyruvate was selected as a model system to demonstrate the capabilities of novel biomimetic reactor systems developed in our laboratory. They couple membrane and electrode technologies that isolate key mechanistic steps. Porous graphite electrodes utilize an immobilized enzyme system (lipoamide dehydrogenase and methyl viologen as a mediator) encapsulated by a cation exchange membrane (Nafion 124). The free flowing fluid contains the pyruvate/lactate (and coproducts), the enzyme lactate dehydrogenase and the NADH/NAD+ system. This lactate synthesis reaction is controlled by mass transfer and/or reaction kinetics, in either the solution “phase” or within the enzyme-electrode itself, dependent upon system configuration and operating parameters. These electrode transport studies identify optimum configurations with respect to enzyme loading and pore size