Microbiorhodopsin a powerful candidate for a photosensitizer of the TiO2-based pollutant degradation system

Abstract

Bacteriorhodopsin (BR) is a light driven proton pump firstly found in the membrane of Halobacterium salinarum. Because of its high quantum efficiency, high stability under harsh conditions and many interesting photochemical properties, BR was shown to be able to enhance the performance of TiO2 materials in TiO2-based solar cell, photocatalytic water splitting and photocatalytic degradation of pollutants. However, high cost of the preparation of the BR restricts its industrial application. Although numerous attempts have been made, E. coli-expression system of the BR, which is most economic and fast way to prepare proteins, has not been developed yet. In the present work, we successfully expressed BR homolog, Archaerhodopsin (AR) found in a Halorubrum species by E. coli-expression system. The E. coli expressed AR retained its photoactivity and showed similar photoreaction properties as that of BR. The E. coli expressed AR might be an excellent candidate for a photosensitizer of the TiO2-based solar energy conversion system.