Energy-transfer dynamics in three light-harvesting mutants of Rhodobacter sphaeroides: a picosecond spectroscopy study.
Picosecond absorption spectroscopy has been used to investigate energy-transfer dynamics within the LH1 and LH2 light-harvesting complexes of three mutants of Rhodobacter sphaeroides. We demonstrate that both complexes are inhomogeneous; each contains a specialized pigment pool which absorbs maximally at a longer wavelength. Within LH2 (mutant NF57), Bchl850 transfers energy to Bchl870 in 39 +/- 9 ps; within LH1 (mutants M21 and M2192), energy is transferred from Bchl875 to Bchl896 in 22 +/- 4 and 35 +/- 5 ps, respectively. Examination of the decay of induced absorption anisotropy indicates that each of these specialized pools exists in a state which is highly organized with respect to the remainder of the pigments. Such an arrangement may facilitate and direct energy migration toward the reaction center.
Hunter
C N
CN
Department of Physical Chemistry, University of Umeå, Sweden.
Bergström
H
H
van Grondelle
R
R
Sundström
V
V
D004735:Energy Transfer; D005454:Fluorescence Polarization / Q000379:methods; D007700:Kinetics; D008027:Light; D009154:Mutation; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000378:metabolism*