Fluorescence properties of the light-harvesting bacteriochlorophyll protein from Rhodopseudomonas sphaeroides R-26 |
| |
Authors: | John D. Bolt Kenneth Sauer |
| |
Affiliation: | Chemistry Department and Laboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 U.S.A. |
| |
Abstract: | The light-harvesting bacteriochlorophyll-protein (BChl-protein) from Rhodopseudomonas sphaeroides, R-26 mutant, exhibits a strong optical absorption peak near 850 nm (Qy band) and a weaker peak at 590 nm (Qx band). This pigment-protein appears to contain two BChl molecules per subunit, and previous circular dichroism studies indicated the presence of excitonic interactions between the BChl molecules. The complex exhibits a fluorescence maximum near 870 nm at room temperature. Excitation in the Qy region results in polarization p values that vary only from +0.12 at 820 nm to +0.14 near 900 nm. These values are appreciably smaller than that for monomeric BChl in viscous solvents (p > 0.4). By contrast, using Qx excitation the p value is ?0.25 for the BChl-protein complex, which is close to that observed for the BChl monomer. For the BChl-protein these polarization values do not change greatly at a temperature of 90 K; however, the Stokes' shift of the fluorescence emission increases significantly over that at room temperature. |
| |
Keywords: | Fluorescence polarization Exciton coupling Bacterial photosynthesis Bacteriochlorophyll-protein complex (Rps. sphaeroides) BChl bacteriochlorophyll SDS sodium dodecyl sulfate |
本文献已被 ScienceDirect 等数据库收录! |
|