Abstract
Most Chl a in the PS1RC complexes was removed without any loss of P700 by ether treatment, yielding the antenna-depleted complexes that contain about 13 Chl a/P700. (1) On addition of Chl d with phospholipids (PG), about one-fourth of the added Chl d was bound to the complexes, of which ratio was smaller than that of the exogenously added Chl a, suggesting a low affinity of Chl d to the Chl a-binding sites. (2) The initial rate of the P700 photooxidation was increased by the binding of Chl d, but only with about a half efficiency of the bound Chl a. (3) The Chl d-bound PS1 complexes emitted the fluorescence both from Chl a and d. The excitation spectra showed the excitation energy equilibration between Chl a and d. These results suggest that the bound Chl d acts as an energy sink, transferring its excitation energy to P700.
