Directed picosecond excitation transport in purple photosynthetic bacteria

Summary, in English

Picosecond spectrally resolved fluorescent measurements together with the coupled kinetic rate equation model simulations of the data have been employed to determine the rates and pathways of heterogeneous excitation transport in the membranes of photosynthetic bacteria Rhodobacter sphaeroides and Chromatium minutissimum. Excitation transport from bacteriochlorophyll molecules B800 to B850, belonging to the same pigment-pigment-protein complex B800-850, proceeds in 1-2 ps at room temperature and at 77 K. The intercomplex excitation transport from B850 to B875 takes about 10 ps for most excitations. In the minor part of B800-850 complexes, the excitation transport to B875 complex takes much longer, about 50 ps. The macroscopic rate constant of excitation trapping by open reaction centres is shown to be the same for all the bacteria studied, although the number of antenna molecules per reaction centre differs significantly. This seems to be an indication of the intrinsic homogeneity of the long-wavelength bacteriochlorophyll band, which facilitates an additional localization of excitations in the vicinity of the reaction centre and, due to the shortening of the trapping time, increases the overall quantum yield of photosynthesis.

• Author: A. Freiberg; V. I. Godik; T. Pullerits; K. Timpmann
• Publishing year: 1988-12-01
• Language: English
• Pages: 227-235
• Publication/Series: Chemical Physics
• Volume: 128
• Issue: 1
• Links: http://dx.doi.org/10.1016/0301-0104(88)85073-0
• Document type: Journal article
• Publisher: Elsevier
• Status: Published
• ISBN/ISSN/Other: ISSN: 0301-0104