LIGHT-DRIVEN PROTON PUMPS OF ARCHAERHODOPSIN AND BACTERIORHODOPSIN AND POLYMER-MATRIX COMPOSITE MATERIALS OF THOSE FUNCTIONAL PROTEINS

Combination of biomacromolecules with biological activity and conventional synthetic polymers with good mechanical and processing properties to prepare hybrid materials is a new branch in Material Science. This paper summarizes the investigations of two light-driven proton pumps, bacteriorhodopsin (BR) and archaerhodopsin 4 (AR4),with emphasis of the work by the authors' group and their cooperators in the latest decade. While BR was found forty years ago, AR4 is relatively new and was found by Chinese researchers one decade ago. In this first review about AR4, the authors made comparison between AR4 and BR, introduced their work of preparation of composite films composed of these retinal proteins and polymers. The review summarizes a series of the achievements by the authors and their cooperators, for instance: (1) revealing the mechanism of the light-driven proton pump in AR4 and putting forward a weak-coupling model; (2) finding that gellable amphiphilic polymers could enhance the relaxation time of AR4 and BR very significantly; (3) developing techniques of encapsulating BR and AR4 into polymeric hydrogels; (4) finding that a purple membrane containing retinal proteins can resist adhesion of mammalian cells; (5) a successful information recording based upon protein-polymer composite films. Finally, the future research and potential applications of the retinal proteins and corresponding functional materials are prospected.