Influence of Replacing Bacterial Pheophytin with Pheophytin on the Picosecond Fluorescence from Reaction Centers of Purple Bacteria

Results showed that pheophytin substituion influences the composition of fluorescence spectra. Therefore, four, three and two components were obtained from fluorescence spectra of native RC, Bphe_(B)-replaced RC and Bphe_(A,B)-replaced RC, respectively. Fluorescence components are well correlated to the binding of plant pheophytin. The decay of excited state of primary electron donor P in different RCs was also studied by measuring the fluorescence decay at 686.4, 674.1 and 681.1 nm, respectively. The decaying kinetics changed in different RCs, indicating that theophytin replacement influenced the energy transduction and primary photochemical reaction in purple bacterial reaction centers.