Premium
Ultrafast chlorophyll b ‐chlorophyll a excitation energy transfer in the isolated light harvesting complex, LHC II, of green plants
Author(s) -
Pålsson Lars Olof,
Spangfort Michael D.,
Gulbinas Vidmantas,
Gillbro Tomas
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80400-1
Subject(s) - chlorophyll a , chlorophyll b , chlorophyll , chemistry , chromophore , ultrafast laser spectroscopy , absorption (acoustics) , absorption spectroscopy , analytical chemistry (journal) , spectroscopy , photochemistry , atomic physics , physics , optics , biochemistry , organic chemistry , chromatography , quantum mechanics
The excitation energy transfer between chlorophyll b (Chl b ) and chlorophyll a (Chl a ) in the isolated trimeric chlorophyll‐ a/b ‐binding protein complex of spinach photosystem 2 (LHC II) has been studied by femtosecond spectroscopy. In the main absorption band of Chl b the ground state recovery consists of two components of 0.5 ps and 2.0 ps, respectively. Also in the Chl a absorption band, at 665 nm, the ground state recovery is essentially bi‐exponential. In this case is, however, the fastest relaxation lifetime is a 2.0 ps component followed by a slower component with a lifetime in the order of 10–20 ps. In the Chl b absorption band a more or less constant anisotropy of r = 0.2 was observed during the 3 ps the system was monitored. In the Chl a absorption band there was, however, a relaxation of the anisiotropy from r = 0.3 to a quasi steady state level of r = 0.18 in about 1 ps. Since the 0.5 ps component is only seen upon selective excitation of Chl b we assign this component to the energy transfer between Chl b and Chl a . The other components most likely represents redistribution processes of energy among spectrally different forms of Chl a . The energy transfer process between Chl b and Chl a can well be explained by the Förster mechanism which also gives a calculated distance of 13 Å between interacting chromophores. The organisation of chlorophylls in LHC II is discussed in view of the recent crystal structure data (1991) Nature 350, 130].