Spectroscopic properties of the light-harvesting complexes from Rhodospirillum molischianum.

Spectroscopic properties, including low-temperature absorbance, linear and circular dichroism and site-selection fluorescence of the antenna complexes from Rhodospirillum molischianum have been determined. The unique 'LH1-like' character of the amino acid sequence from LH2 of this bacterium is reflected in the circular dichroism of the B850 band of this complex. The wavelength dependence of the polarization of the LH2 complex shows an unusual shape that is attributed to the octameric state of this complex. The complete amino acid sequence for the LH1 alpha-polypeptide and most of the beta-polypeptides are presented. These conform to the general features of other LH1 polypeptides. This result, in combination with spectroscopic data for LH1 imply that the organisation of the core in this bacterium is not much different from that in other purple non-sulphur bacteria.