Effect of the mutation of carotenoids on the dynamics of energy transfer in light-harvesting complexes （LH2） from Rhodobacter sphaeroides 601 at room temperature

Energy transfers in two kinds of peripheral light-harvesting complexes （LH2） of Rhodobacter sphaeroides （RS） 601 are studied by using femtosecond pump^probe spectroscopy with tunable laser wavelength at room temperature. These two complexes are native LH2 （RS601） and green carotenoid mutated LH2 （GM309）. The obtained results demonstrate that, compared with spheroidenes with ten conjugated double bonds in native RS601, carotenoid in GM309 containing neurosporenes with nine conjugated double bonds can lead to a reduction in energy transfer rate in the B800-to-B850 band and the disturbance in the energy relaxation processes within the excitonic B850 band.