Reconstitution of energy converting proteins in biocompatible materials

As technology approaches a new era of device miniaturization, a compact and more efficient power source to drive these devices are in demand. It is worth exploring the potential of nanometer-scale hybrid organic/inorganic devices as an alternative to conventional power sources that have obvious limitations in size miniaturization. Some proteins in nature have played critical roles of energy conversion and transduction in biological systems over millions of years. There have been attempts to utilize energy converting proteins in laboratories in vivo. Although most in vivo experiments provide the most accurate recreation of the natural environments for membrane bound proteins, these conditions carry discrepancies from uncontrollable biological reactions. It is necessary to produce a more convenient experimental environment in which protein structure and function are maintained in vitro. We are engineering a biocompatible membrane embedded with energy converting proteins: bacteriorhodopsin (BR) and cytochrome oxidase (COX). Light absorption initiates transfer of protons by BR from one side of the artificial membrane to the other, creating an electro-chemical gradient that turn drives COX backwards. Reversed COX mechanism generates intermediates from O₂ to H₂O along with electrons. These electrons are attracted to a metal electrode that serves as current reservoir. The system converts optical energy to electrical energy, eventually allocating the derived energy to an external source.