MECHANISMS OF CHOSEN ENZYME REACTIONS - New Trends in Enzyme Catalysis and Biomimetic Chemical Reactions - page 121

Primary photochemical events in reaction centers from the Rb. sphaeroides wild type
and site directed mutant RCs, where the tyrosine at the M210 position was replaced by
phenylalanine and leucine, were investigated by femtosecond time-resolved absorbance
and ENDOR/TRIPLE spectroscopy techniques (Wachtveitl, et al., 1998). The results
allowed the authors to suggest that primary electron transfer follows a stepwise
mechanism and state is the first electron transfer intermediate in these mutants.
Independent evidence in favor of the anion radical as the first material (but not
“virtual”) intermediate, was obtained (Yakovlev et al., 2000). It was demonstrated that in
the porphyrin-modified RCs of Rb. spheroidas R-26, the femtosecond oscillations in the
excited primary donor emission occur (Vos et al., 1994).
Primary photochemical events in two site-directed mutants YF(M208) and
YL(M208) of RC from Blastochloris viridis, in which tyrosine at position M208 is
replaced by phenylalanine and leucine, respectively, were investigated with the use of
1H-ENDOR as well as optical absorption spectroscopy (Mue et al., 2000). The residue at
M208 is in close proximity to the primary electron donor, P, the (BChl), and the BPh.
Analysis of the experimental data revealed two torsional isomers of the 3-acetyl group of