Ultrafast spectroscopy of trimeric light-harvesting complex II from higher plants
- Max-Planck-Institut fuer Strahlenchemie, Muelheim an der Ruhr (Germany)
- Univ. of Sheffield (United Kingdom)
Time-resolved femtosecond transient absorption measurements have been carried out at room temperature on light-harvesting chlorophyll a/b protein complex of photosystem II (LHC II) trimers prepared from spinach. Exciting in the chlorophyll (Chl) b region at 650 nm with very low intensity, virtually annihilation-free two-color transient absorption measurement of the kinetics over 100 ps, between 645 and 690 nm, yield global lifetimes of 175 fs, 625 fs, and 5 ps and a long component (>=790 ps) where the three fastest lifetimes reflect Chl b to Chl a energy transfer. On the basis of these results and recent electron diffraction structural data, a preliminary three-pool Ch a, three-pool Chl b kinetic model is proposed. The possible influence of variable xanthophyll composition on quenching in LHC II preparations isolated from light- and dark-adapted leaves has been investigated using time-resolved picosecond fluorescence at room temperature. Global lifetimes of 5 ps and 3.6 ns, the lifetimes of the terminal LHC II excited state, were obtained. No discernable quenching effect due to the presence of zeaxanthin was observed. 38 refs., 6 figs., 3 tabs.
- OSTI ID:
- 501896
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 101, Issue 10; Other Information: PBD: 6 Mar 1997
- Country of Publication:
- United States
- Language:
- English
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