Biomembrane Technology and Biomolecular Photonics

Kenneth Rothschild

The design of a new generation of materials based on biomembrane components holds promise in diverse areas including optical recording media, chemical sensors, nanometer lithography, energy transducers, and enzyme catalysts. A variety of membrane proteins, including bacteriorhodopsin, rhodopsin, and acetylcholine receptor, exhibit active properties such as energy transduction, active and passive transport, chemical sensing, voltage channel gating, signal transduction, and self-assembly, which could find important uses in such materials. However, future progress will depend on the development of new methods for engineering such biomolecules with properties including enhanced stability and the ability to exist in a solid-state environment so that they are suitable for use in biomolecular devices.

In this project, the biophysics group is developing new methods based on molecular genetics and advanced biophysical techniques that will provide the capability to modify membrane proteins at the molecular level. Key among these techniques will be site-directed non-native amino acid replacement (SNAAR). This approach will provide a new dimension in protein engineering, enabling the replacement of native amino acid residues with custom designed residues. Current studies are aimed at incorporating photoactive non-native residues that will alter the electro-optical properties of bacteriorhodopsin. In this regard, recent studies have demonstrated that films produced from bacteriorhodopsin can be used for optical information processing.

The group has also demonstrated recently that self-assembled biomembranes can be used as molecular templates for nanostructure material fabrication. In one set of experiments, in collaboration with N. Clark and K. Douglas at the University of Colorado, 2-dimensionally crystalline S-layers were used as templates to produce patterned thin metal films with nanometer-sized holes and wires. In a different study (in collaboration with C. Safinya at the University of California Santa Barbara), the group recently reported the discovery that dry films of bacteriorhodopsin are structurally stable up to 140oC. Studies are being conducted to produce heatproof arrays of other proteins.