Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates.

摘要: Abstract We have examined the photophysics of energy migration and trapping in photosystem I by investigating spectral temporal properties fluorescence from core antenna chlorophylls as a function size. Time-correlated single photon counting was used to determine lifetimes isolated P700 chlorophyll a-protein complex mutant Chlamydomonas reinhardtii that lacks II reaction center complex. The decay both types sample is dominated fast (15-45 psec) component attributed lifetime excitations antenna. These primarily an efficient photochemical quenching on P700. measured show linear relationship A dependence excitation size predicted previously lattice model for arrays photosynthetic pigments [Pearlstein, R.M. (1982) Photochem. Photobiol. 35, 835-844]. Based this model, our data predict time constant charge separation 2.8 +/- 0.7 or 3.4 psec, assuming monomeric dimeric P700, respectively. average single-step transfer between 0.21 0.04 psec. Under these conditions, near diffusion limit, with each making 2.4 visits before photoconversion.