Linear dichroism of light harvesting bacteriochlorophyll proteins from Rhodopseudomonas sphaeroides in stretched polyvinyl alcohol films |
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Authors: | John Bolt Kenneth Sauer |
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Institution: | Department of Chemistry and Laboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 U.S.A. |
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Abstract: | Light-harvesting bacteriochlorophyll-protein complexes from Rhodopseudomonas sphaeroides 2.4.1 and R-26 mutant are solubilized in sodium dodecyl sulfate and imbedded in polyvinyl alcohol. Stretching induces orientation, and the linear dichroism of visible and near infrared absorption is analyzed. Based on a simple model, angles between the particle axis and the transition dipole moments are found. In the near infrared absorption band of the R-26 light-harvesting protein the dichroic ratio varies from 1.30 to 1.57. Using the absorption curves the band is resolved into two exciton components. In the visible absorption band the dichroic ratio has a constant value of 0.43 for the R-26 protein but varies with wavelength for the wild type light-harvesting protein. This variation is attributed to an additional bacteriochlorophyll not present in the R-26 protein. |
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Keywords: | Linear dichroism Bacteriochlorophyll Light-harvesting protein Bacterial photosynthesis Reaction center (Rhodopseudomonas sphaeroides) LH-wt LH-R26 SDS sodium dodecyl sulfate |
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