Transcript of Carotenoids in Photosynthesis quenching triplet (B)Chl excited states direct role in scavenging of...
- Slide 1
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- Carotenoids in Photosynthesis quenching triplet (B)Chl excited
states direct role in scavenging of singlet oxygen deactivation of
Chl excited states (NPQ) redox activity in PSII reaction centers
antenna chromophores for the mid- visible part of the solar
spectrum LHCII trimer (2BHW.pdb) Standfuss et al. EMBO J. 2005, 24,
919. -carotene Frank, H. A.; Brudvig, G. W. Biochemistry 2004, 43,
8607-8615.
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- Excitation Energy Transfer from Carotenoids to Chlorophylls
Optical transitions between the carotenoid S and S states are
forbidden by symmetry (C 2h point group). Birge, R. R. Acc. Chem.
Res. 1986, 19, 138-146. Carotenoids(B)Chls S2S2 S1S1 S0S0
11Bu+11Bu+ 21Ag21Ag 11Ag11Ag A F T1T1 QxQx QyQy S0S0 T1T1 F A
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- Peridinin PeridininChlorophyll a Protein (1PPR) Hofmann et al.
Science 1996, 272, 1788.
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- Intramolecular Charge Transfer in Peridinin Hypothesis: The S
state of peridinin enhances energy transfer to the Q y state of
chlorophyll a by obtaining an intramolecular charge-transfer (ICT)
character. Ilagan et al. Biochemistry 2006, 45, 14052.
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- Third-Order Nonlinear Spectroscopy Stimulated photon-echo and
transient-grating spectroscopy with optical heterodyne detection.
DO Sample ND WP () 1 and 2 3 and LO signal Miller and coworkers,
Proc. Natl. Acad. Sci. U.S.A. 2001, 98, 6110. Fleming and
coworkers, J. Chem. Phys. 2004, 121, 4221. Scherer and coworkers,
J. Chem. Phys. 2006, 124, 194904. -carotene
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- Fourier Transform Spectral Interferometry Isolation of the
third-order nonlinear signal as the interference term at t LO
Phasing Signal (Real) Window at t LO FT -1 Complex FT Complex Real
component = Absorption Imaginary component = Dispersion
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- -carotene Heterodyne transient-grating signal in benzonitrile
S2S2 IS1S1 S0S0 16 fs142 fs9 ps / 12 ps
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- -carotene Heterodyne transient-grating signal in benzonitrile
An intermediate state is formed from the initially formed S state
in 16 fs. S2S2 IS1S1 S0S0 16 fs142 fs9 ps / 12 ps
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- -carotene Heterodyne transient-grating signal in benzonitrile
An intermediate state is formed from the initially formed S state
in 16 fs. The intermediate decays to the S state in 142 fs, which
is comparable to the fluorescence lifetime detected in upconversion
experiments. S2S2 IS1S1 S0S0 16 fs142 fs9 ps / 12 ps
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- -carotene Heterodyne transient-grating signal in benzonitrile
The dispersion and absorption recovery time constants show that a
"hot" or conformationally displaced ground-state ensemble is
produced by nonradiative decay of the S state. Xu et al. J. Chem.
Phys. 2002, 116, 9333. S2S2 IS1S1 S0S0 16 fs142 fs9 ps / 12 ps
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- Peridinin Heterodyne transient-grating signal in methanol S2S2
IS1S1 S0S0 31 fs615 fs7 ps / 11 ps
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- Peridinin Heterodyne transient-grating signal in methanol The
decay of the intermediate is strongly dependent on the polar
solvation timescale. Solvent polar SIS ethyl acetate2.5 ps23 fs160
fs85 ps / 150 ps methanol6.2 ps31 fs615 fs7 ps / 11 ps
2-propanol220 ps35 fs1600 fs29 ps / 49 ps S2S2 IS1S1 S0S0 31 fs615
fs7 ps / 11 ps
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- Peridinin Heterodyne transient-grating signal in methanol The
decay of the intermediate is strongly dependent on the polar
solvation timescale. But the S state lifetime is dramatically
lengthened as the polarity of the solvent decreases. Bautista et
al. J. Phys. Chem. B 1999, 103, 8751. SolventPolaritySIS ethyl
acetate0.62623 fs160 fs85 ps / 150 ps methanol0.91331 fs615 fs7 ps
/ 11 ps 2-propanol0.85235 fs1600 fs29 ps / 49 ps S2S2 IS1S1 S0S0 31
fs615 fs7 ps / 11 ps
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- PeridininChlorophyll a Protein Heterodyne transient-grating
signal The intermediate state is the energy-transfer donor to the Q
x state of Chl a. 31 fs500 fs16 ps / 16 ps S2S2 IS1S1 S0S0 QxQx
QyQy 200 fs 3 ps
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- PeridininChlorophyll a Protein Heterodyne transient-grating
signal The intermediate state is the energy-transfer donor to the Q
x state of Chl a. The absorption and dispersion components for the
decay of S have the same time constant, so conformational
relaxation does not make a strong contribution to the recovery to
the photoselected ground state. 31 fs500 fs16 ps / 16 ps S2S2 IS1S1
S0S0 QxQx QyQy 200 fs 3 ps
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- -carotene Time-resolved transient grating spectra in
benzonitrile The S state decays as the stimulated emission
contribution to the signal shifts irreversibly to the red. S2S2
IS1S1 S0S0 16 fs142 fs9 ps / 12 ps
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- -carotene Time-resolved transient grating spectra in
benzonitrile The S state decays as the stimulated emission
contribution to the signal shifts irreversibly to the red. The ESA
spectrum shifts to the red as the intermediate forms, and then it
shifts back to the blue as the S state forms. S2S2 IS1S1 S0S0 16
fs142 fs9 ps / 12 ps
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- -carotene Time-resolved transient grating spectra in
benzonitrile The S state decays as the stimulated emission
contribution to the signal shifts irreversibly to the red. The ESA
spectrum shifts to the red as the intermediate forms, and then it
shifts back to the blue as the S state forms. Similar ESA dynamics
(and the same time constants) are observed in the ESA in the red
and near-IR part of the spectrum. Cerullo et al. Science 2002, 298,
2395. S2S2 IS1S1 S0S0 16 fs142 fs9 ps / 12 ps
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- Four-Mode Dynamics Four coordinates control the nonradiative
decay of -carotene and peridinin in solution. Sanchez-Galvez, A.;
Hunt, P.; Robb, M. A.; Olivucci, M.; Vreven, T.; Schlegel, H. B. J.
Am. Chem. Soc. 2000, 122, 2911-2924.
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- Four-Mode Dynamics Four coordinates control the nonradiative
decay of -carotene and peridinin in solution. 1.Bond-alternation
(CC, C=C) coordinates in the FranckCondon region Sanchez-Galvez,
A.; Hunt, P.; Robb, M. A.; Olivucci, M.; Vreven, T.; Schlegel, H.
B. J. Am. Chem. Soc. 2000, 122, 2911-2924.
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- Four-Mode Dynamics Four coordinates control the nonradiative
decay of -carotene and peridinin in solution. 1.Bond-alternation
(CC, C=C) coordinates in the FranckCondon region 2.Torsional
coordinates () over the S-state barrier and to a twisted minimum
Sanchez-Galvez, A.; Hunt, P.; Robb, M. A.; Olivucci, M.; Vreven,
T.; Schlegel, H. B. J. Am. Chem. Soc. 2000, 122, 2911-2924.
- Slide 23
- Four-Mode Dynamics Four coordinates control the nonradiative
decay of -carotene and peridinin in solution. 1.Bond-alternation
(CC, C=C) coordinates in the FranckCondon region 2.Torsional
coordinates () over the S-state barrier and to a twisted minimum
3.Out-of-plane motions () that produce a pyramidal structure in the
S state with enhanced ICT character. Sanchez-Galvez, A.; Hunt, P.;
Robb, M. A.; Olivucci, M.; Vreven, T.; Schlegel, H. B. J. Am. Chem.
Soc. 2000, 122, 2911-2924. Levine, B.; Martnez, T. J. Annu. Rev.
Phys. Chem. 2007, 58, 613.
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- Four-Mode Dynamics Four coordinates control the nonradiative
decay of -carotene and peridinin in solution. 1.Bond-alternation
(CC, C=C) coordinates in the FranckCondon region 2.Torsional
coordinates () over the S-state barrier and to a twisted minimum
3.Out-of-plane motions () that produce a pyramidal structure in the
S state with enhanced ICT character. 4.Solvent motions that are
coupled to formation of intramolecular charge- transfer character
near the the twisted minimum. Sanchez-Galvez, A.; Hunt, P.; Robb,
M. A.; Olivucci, M.; Vreven, T.; Schlegel, H. B. J. Am. Chem. Soc.
2000, 122, 2911-2924. Levine, B.; Martnez, T. J. Annu. Rev. Phys.
Chem. 2007, 58, 613. Malhado, J. P.; Spezia, R.; Hynes, J. T. J.
Phys. Chem. A 2011, 115, 3720-3735.
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- PeridininChlorophyll a Protein Time-resolved transient grating
spectra The earliest PCP spectra are comparable in shape to the 50
fs peridinin/methanol spectrum. The structure of peridinin in PCP
is like that for the twisted S state in solution. S2S2 IS1S1 S0S0
31 fs500 fs16 ps / 16 ps
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- Binding-Site Control of Dynamics in PCP The X-ray crystal
structure suggests that a twisted and kinked structure is favored
by the peridinin binding site in PCP. Hofmann et al. Science 1996,
272, 1788. Shima et al., J. Phys. Chem. A 107, 8052 (2003).
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- Conclusions and Next Steps
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- 1.In PCP, the twisted S state intermediate serves as the
energy-transfer donor to the Chl a Q x state.
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- Conclusions and Next Steps 1.In PCP, the twisted S state
intermediate serves as the energy-transfer donor to the Chl a Q x
state. 2.The S state of peridinin may obtain an enhanced ICT
character by forming a kinked (pyramidal) conformation.
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- Conclusions and Next Steps 1.In PCP, the twisted S state
intermediate serves as the energy-transfer donor to the Chl a Q x
state. 2.The S state of peridinin may obtain an enhanced ICT
character by forming a kinked (pyramidal) conformation. 3.The
structure of the peridinin-binding pocket favors a twisted and
kinked ground-state conformer.
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- Conclusions and Next Steps 1.In PCP, the twisted S state
intermediate serves as the energy-transfer donor to the Chl a Q x
state. 2.The S state of peridinin may obtain an enhanced ICT
character by forming a kinked (pyramidal) conformation. 3.The
structure of the peridinin-binding pocket favors a twisted and
kinked ground-state conformer. Broadband 2D spectra to characterize
the energy correlation of the twisted/pyramidal intermediates with
the S state and with the Chl a acceptors in PCP.
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- Acknowledgment Amy LaFountain (Uconn) Professor Andrew Moran
(UNC Chapel Hill) Professor Ben Levine (MSU) NSF MCB-0920101 DOE
BES DE-SC0010847