Kinetics of excitation trapping in intact Photosystem I of Chlamydomonas reinhardtii and Arabidopsis thaliana

We measured picosecond time-resolved fluorescence of intact Photosystem I complexes from Chlamydomonas reinhardtii and Arabidopsis thaliana. The antenna system of C reinhardtii contains about 30-60 chlorophylls more than that of A. thaliana, but lacks the so-called red chlorophylls, chlorophylls that absorb at longer wavelength than the primary electron donor. In C reinhardtii, the main lifetimes of excitation trapping are about 27 and 68 ps. The overall lifetime of C reinhardtii is considerably shorter than in A. thaliana. We conclude that the amount and energies of the red chlorophylls have a larger effect on excitation trapping time in Photosystem I than the antenna size. (C) 2004 Elsevier B.V. All rights reserved.