Correlation of Car S(1) → Chl with Chl → Car S(1) energy transfer supports the excitonic model in quenched light harvesting complex II.
Recently, excitonic carotenoid-chlorophyll interactions have been proposed as a simple but effective model for the down-regulation of photosynthesis in plants. The model was proposed on the basis of quenching-correlated electronic carotenoid-chlorophyll interactions (Car S(1) → Chl) determined by Car S(1) two-photon excitation and red-shifted absorption bands. However, if excitonic interactions are indeed responsible for this effect, a simultaneous correlation of quenching with increased energy transfer in the opposite direction, Chl Q(y) → Car S(1), should be observed. Here we present a systematic study on the correlation of Car S(1) → Chl and Chl → Car S(1) energy transfer with the occurrence of red-shifted bands and quenching in isolated LHCII. We found a direct correlation between all four phenomena, supporting our conclusion that excitonic Car S(1)-Chl interactions provide low-lying states serving as energy traps and dissipative valves for excess excitation energy.
Technische Universität Braunschweig, Institute for Physical and Theoretical Chemistry, Department for Biophysical Chemistry, Hans-Sommer-Strasse 10, 38106 Braunschweig, Germany.
Pen-Nan
PN
Liao
Christoph-Peter
CP
Holleboom
Laura
L
Wilk
Werner
W
Kühlbrandt
Peter J
PJ
Walla
D002734:Chlorophyll / Q000737:chemistry; D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D008958:Models, Molecular; D013050:Spectrometry, Fluorescence
D045342:Light-Harvesting Protein Complexes; D002734:Chlorophyll