Vi. Godik et al., TIME-RESOLVED TRYPTOPHAN FLUORESCENCE IN PHOTOSYNTHETIC REACTION CENTERS FROM RHODOBACTER-SPHAEROIDES, FEBS letters, 321(2-3), 1993, pp. 229-232
Tryptophan fluorescence of reaction centers isolated from Rhodobacter
sphaeroides, both stationary and time-resolved, was studied. Fluoresce
nce kinetics were found to fit best a sum of four discrete exponential
components. Half of the initial amplitude was due to a component with
a lifetime of congruent-to 60 ps, belonging to Trp residues, capable
of efficient transfer of excitation energy to bacteriochlorophyll mole
cules of the reaction center. The three other components seem to be em
itted by Trp ground-state conformers, unable to participate in such a
transfer. Under the influence of intense actinic light, photooxidizing
the reaction centers, the yield of stationary fluorescence diminished
by congruent-to 1.5 times, while the number of the kinetic components
and their life times remained practically unchanged. Possible implica
tions of the observed effects for the primary photosynthesis events ar
e considered.