Ruban et al Figure 4

1
Ruban et al Figure 4
2
Carotenoid-Zn phthalocyanin dyads
9-double bond carotenoid
Pc
dyad 1
car
10-double bond carotenoid
Pc
dyad 2
car
Berera et al PNAS 2006
3
Phthalocyanin singlet quenching by
carotenoids Excitation, detection 680 nm
300 ps
3 ns
THF intermediate polarity
4
MODEL SYSTEM
Carotenoid ground state bleach
excited state abs. quenching state
In this simple system energy transfer from the
tetrapyrrole to the carotenoid has been
established
Berera, R., Herrero, C., van Stokkum, L. H. M.,
Vengris, M., Kodis, G., Palacios, R. E., van
Amerongen, H., van Grondelle, R., Gust, D.,
Moore, T. A., Moore, A. L. Kennis, J. T. M.
(2006) Proceedings of the National Academy of
Sciences of the United States of America 103,
5343-5348.
5
Tetrapyrrole singlet excited-state quenching by
carotenoid S1 mediated via carotenoid ICT
state switched on by addition of 1 double bond
6
Is LHCII a Switch?????? Single Molecule
Fluorescence
7
(No Transcript)
8
Variation in disorder results in spectral
fluctuations
9
four-state model (2)
10
(No Transcript)
11
(No Transcript)
12
Single LHCII Emission Spectra
13
Single LHCII Emission Spectra
Sometimes a broad emission band at 720-730 nm
appears!!!!!!
14
670-700 nm Spectral Fluctuations Are Explained by
Variations in Disorder in Normal LHCII.
15
But the appearance of the 720-730 nm
emission? Requires the mixing of a
charge-transfer state with one of the exciton
states of LHCII.
16
Low T Site-Selective Fluorescence (Croce et al,
Biophys. J. in press)
Plant Photosystem I
17
The switching of Lhc2 to Lhc1?
Lhc2
Lhc1
Emission at 730nm quenched
Emission at 680nm not quenched
18
Acknowledgement
Rudi Berera Biophysics VU Amsterdam Tjaart
Krueger Manolis Papagiannakis Danielis
Rutkauskas Natalia Pawlowicz Marloes Groot Ivo
van Stokkum John Kennis Rienk van
Grondelle Vladimir Novoderezhkin Moscow State
University Sasha Ruban, Queen Mary University
of London Peter Horton University of
Sheffield Cristian Ilioaia Bruno Robert CEA
Saclay Andy Pascal Jacques Breton CEA
Saclay Herbert van Amerongen Laboratory of
Biophysics, Wageningen Tom Moore Arizona State
University Ana Moore
19
Acknowledgements
Rudi Berera Biophysics VU Amsterdam Tjaart
Krueger Manolis Papagiannakis Danielis
Rutkauskas Natalia Pawlowicz Marloes Groot Ivo
van Stokkum John Kennis Rienk van
Grondelle Vladimir Novoderezhkin Moscow State
University Sasha Ruban, Queen Mary University
of London Peter Horton University of
Sheffield Cristian Ilioaia Bruno Robert CEA
Saclay Andy Pascal Jacques Breton CEA
Saclay Herbert van Amerongen Laboratory of
Biophysics, Wageningen Tom Moore Arizona State
University Ana Moore
20
Spectroscopy of LHC-II
ODLD
Low Temperature Fluorescence
calculated
21
(No Transcript)
22
Quenching solvent polarity dependence
traces at 680 nm, acetone
dyad 1
dyad 2
dyad 3
300 ps
THF
3 ns
60ps
acetone
600ps
60ps
16ps
DMSO
300ps
53ps
23ps
near-IR spectra for dyad 3 in DMSO
CP_ (9)
CS
Qy
CP_ (10)
CP_ (11)
?A (10-3)
fast
Wavelength (nm)
S0
no electron transfer!
23
(No Transcript)
24
The Photosynthetic Membrane
25
Sample 1
Sample 2
Sample 3
The effect is proportional to the degree of
quenching!!
26
Resonance Raman Conformation of neoxanthin
Neoxanthin in crystals is more twisted than in
isolated trimers.
27
Non-photochemical quenching in Photosystem
II xanthophyll cycle
High light nonphoto- chemical quenching
Low light full use of solar energy
NPQ ? decrease of Chl fluorescence in
chloroplasts ? shortening of Chl singlet
lifetime ? direct Chl quenching by zeaxanthin?
28
(No Transcript)
29
Three Pulse Photon Echo Measures Spectral
Diffusion
k1-k2k3
k2-k1k3
t
T
Coherence time
Population time
30
Three Pulse Echo Peak Shift
Maximum of echo not at ? 0 peak shift
frequency grating by pulses 12
frequency changes during T
grating disappears
gt Peak shift decay with T probes

• Vibrational relaxation
• Solvent/protein relaxation
• Underdamped vibrations
• Energy transfer among the same Chlorophylls

31
3PEPS B800 Rs. molischianum Rps. acidophila