Linear and Nonlinear Spectroscopic Probing of Solute Interactions with Chemically Modified Silica Surfaces

Wirth, Mary J

关键词: ABUNDANCE;    AQUEOUS SOLUTIONS;    BIOLOGY;    EFFICIENCY;    ELECTRIC FIELDS;    ENGINEERS;    FUNCTIONALS;    IRRADIATION;    LIPIDS;    MEMBRANE PROTEINS;    POLYMERS;    PROBES;    PRODUCTION;    PROTEIN STRUCTURE;    PROTEINS;    PROTONS;    PUMPING;    SILICA;    SOLAR ENERGY CONVERSION;    SOLUTES;   

DOI  :  10.2172/1004705
RP-ID  :  DOE/ER/15596-1 Final Report
PID  :  OSTI ID: 1004705
Others  :  TRN: US201108%%102

学科分类：再生能源与代替技术

美国|英语

来源: SciTech Connect

【 摘 要 】

Solar energy conversion through biology would provide a renewable and nonpolluting abundance of energy. The bacterium Halobacterium salinarum converts solar to electrical energy by virtue of a transmembrane protein, bacteriorhodopsin. This transmembrane protein pumps protons across a nonconducting bilayer upon irradiation with green light. The bacterium evolved to perform this function inefficiently. If we were able to understand this process to engineer this protein for efficiency, then inexpensive energy production could be achieved. There are tens of thousands of different types of halobacteria, giving the opportunity to study different efficiencies and relating these to the protein structures. Technology does not yet exist to perform such screening. The goal of this research is to generate new separation technology that can ultimately enable such screening. This involves creating a method for separating oriented and functional transmembrane proteins that remain in an electrically insulating lipid bilayer, with aqueous solutions on either side of the bilayer. A pH change across the lipid bilayer upon irradiation of a known concentration of proteins would probe function. Differences in proton pumping efficiency for different proteins variants would provide structure-function information for engineering the proteins. A schematic diagram from the original proposal is shown here. The idea is that (a) a lipid bilayer supported on a hydrophilic polymer film will make the bilayer fluid, and (b) applying an electric field will cause electrophoretic migration of the transmembrane proteins. We demonstrated this concept experimentally in a paper that was published just after this new grant period started (Lipid Bilayers on Polyacrylamide Brushes for Inclusion of Membrane Proteins, Emily A. Smith, Jason W. Coym, Scott M. Cowell, Victor J. Hruby, Henry I. Yamamura, Mary J. Wirth, Langmuir, 21, 9644-9650, 2005). The electrophoretic mobility was slow (10{sup -8} cm{sup 2}/Vs), and we project that a two order of magnitude increase would make this a practical tool. We are investigating two ways of improving electrophoretic mobility: better polymer supports, and a novel nanoporous medium that suspends the bilayer over free solution.