| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 95 === An unidirectional monolayer of Halobacterium salinarium purple membrane (PM), which had been differently chemically modified or mutagenized, was fabricated on conductive ITO glass through specific molecular interaction for photoelectric studies. First, the Lys129 residue of bacteriorhodopsin (BR), which is a photodriven proton pump protein embedded in PM, was successfully modified by either biotinylation or thiolation. The binding of fluorescently labeled streptavidin with either wild-type (WT) or G241C mutant PM, which had been each modified with amine-reactive sulfo-NHS-LC-LC-biotin, both yielded observable red fluorescent signals. Secondly, derivation of G241C PM was neither achieved by binding with 5 nm nanogold particles nor biotinylation with a thiol-active reagent, unless in the presence of high concentrations of denaturants for the latter case. Nevertheless, the same derivation treatments were both successfully achieved towards WT PM that had been thiolated on Lys129 of BR, suggesting that the steric hindrance on the mutated Cys241 residue is much more significant than that on Lys129. Finally, the photoelectric study revealed that 5 % glutaraldehyde prepared in deionized water without pH adjustment modified the amine–coated ITO glass best for the subsequent covalent binding of streptavidin. Further fabrication of the streptavidin-coated surface with a biotinylated PM led to a 5.5-folds increase in photoresponse, confirming the active function of the photodriven proton pump of BR. This study provides promising results for future preparation of unidirectionally multilayered PM photoelectric chips potentially with high photoresponse.
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