Gaussian decomposition of absorption spectra of peripheral light-harvesting complexes of photosynthetic bacteria

The absorption spectra of light-harvesting complexes (LH2) purified from Rhodobacter sphaeroides in 60% glycerol measured in the 4-300 K temperature range have been analysed in terms of linear combination of symmetric Gaussian subbands. All absorption spectra of LH2 are well fitted with sixteen Gaussian subbands. To attribute them to the B800 and B850 bands, the ratio of the integral intensity of those bands is considered, assuming that it should be close to 2 and independent of temperature. From the analysis of the B850 absorption spectrum it is concluded that the maximal value of the resonance interaction between the pigments in the B850 ring should be 300 and 3 10 cm(-1) at room temperature and 4 K, respectively.