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Photosynthesis 2: Energy conversion and electron conduction in soft matter
LH-II LH-I
cytochrome c2
ATPase
cytoplasm
periplasm
ADP ATP
hbc1
H+
H+
e-
Q/QH2/Q
RC
Electron flow in photosynthesis of cyanobacteria
Electron flow in photosynthesis of purple bacteria
From Nature 411, (2001) 897, W. Kuhlbrandt.
Electron flow in photosynthesis of cyanobacteriaand Plants
backward direction: respiration = food consumption in mammals
Photosynthesis 2: Energy conversion and electron conduction in soft matter
LH-II LH-I
cytochrome c2
ATPase
cytoplasm
periplasm
ADP ATP
hbc1
H+
H+
e-
Q/QH2/Q
RC
Electron flow in photosynthesis of cyanobacteria
Electron flow in photosynthesis of purple bacteria
Role of Thermal Disorder on Electron Transfer in the Photosynthetic Reaction Center
Electron transfer is coupled to the thermal motion of thesurrounding protein.
Particle – Hole Separation in the Reaction Center and Solar Cells
proteinprotein rotated – 900 and stretched
LH-II LH-I
cytochrome c2
ATPase
cytoplasm
periplasm
ADP ATP
hbc1
H+
H+
e-
Q/QH2/Q
RC
Cytochrome c2 docking
Photosynthetic Apparatus of Purple Bacteria
Very Large Conformational Changes
Qo
2Fe2Se-
Qo
cyt c12Fe2S cyt c1
two path-ways for oxidation of Qo site
Iron Sulfur Protein head rotationcan redirect2nd electron
Sergei Izrailev
Photosynthetic Apparatus of Purple Bacteria
Very Large Conformational Changes
ATP synthaseenergy transformation(proton motive force rotation)
elastomechanical coupling
rotatory catalysis(twist conformational change ATP synthesis )
F1
F1
F0
stalk
(from Wang & Oster)
(Walker, Whilce,Fillingame)www.ks.uiuc.edu
Photosynthetic Pathway inCyanobacteria and Plants
bacterio-chlorophyll
bacterio-pheophytin
ubiquinone
Electron Carrying Molecules
chain
chain
chain
Particle – Hole Separation in the Reaction Center and Solar Cells
proteinprotein rotated – 900 and stretched
energy gap
energy gap
The energy gap is Gaussian distributed
Two State QM System Coupled to Protein Matrix
Hamiltonian
Protein matrix is a bath of oscillators linearlycoupled to the electron transfer according to
only a single oscillator considered at present!
First case: Coupling to a single oscillator
Hamiltonian
Protein matrix is a bath of oscillators linearlycoupled to the electron transfer according to
Two State QM System Coupled to Protein Matrix
Second case: Coupling to an ensemble of oscillators
Electron Transfer Process Coupled to the Protein Matrix
Rate for an ensemble of oscillators
But we don’t know all the coupling constants cj ? All we need to know is
Relaxation rate
Solution of Rate Equation
Electron Transfer Process Coupled to the Protein Matrix
Rate for an ensemble of oscillators
But we don’t know all the coupling constants cj ? All we need to know is
Relaxation rate
Electron Transfer Process Coupled to the Protein Matrix
Relaxation rate
energy gap correlation functionenergy gap
rms deviation of energy gap
1994
Temperature Dependence of Electron Transfer Rate
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