PARENT SESSION

Symposium S4Aa Chlorophyll and bilin based antenna systems
Tuesday August 31st, 2004 2:40 PM-4:40 PM Room 511D
Chair: Roberto Bassi
Co-Chair: Herbert van Amerongen

Picosecond fluorescence kinetics in PSI-LHCI complexes from A. thaliana and C. reinhardtii. Janne Ihalainen^*,1, Ivo Stokkum¹, Jan Dekker¹, Rienk van Grondelle¹, ¹ Free University Amsterdam, Amsterdam, the Netherlands

ABSTRACT- We present picosecond fluorescence studies on various isolated PSI-LHCI complexes by means of Streak camera setup with about 4 ps time resolution. We show that the excitation decay by charge separation of PSI-LHCI complexes from the green alga Chlamydomonas reinhardtii has components of 30 and 70 ps. Despite of the larger number of bound Lhca proteins in C. reinhardtii, the kinetics is faster than that of green plant Arabidopsis thaliana, where the main trapping times are about 50 and 120 ps. We also show, by using PSI-LHCI particles obtained from plants with antisense constructs against one of the Lhca proteins, that when Lhca proteins with red pigments are lacking, the overall decay lifetime also decreases. Both observed differences are explained by a variable amount of red pigments in the peripheral antenna.

KEY WORDS: Excitation kinetics, PSI-LHCI particle, Time-resolved fluorescence