Photosynthesis 2: Energy conversion and electron conduction in soft matter Electron flow in photosynthesis of cyanobacteria H+ ADP ATP cytoplasm Q/QH2/Q hn ATPase bc1 RC LH-II LH-I periplasm e- H+ cytochrome c2 Electron flow in photosynthesis of purple bacteria

Electron flow in photosynthesis of cyanobacteria and Plants backward direction: respiration = food consumption in mammals From Nature 411, (2001) 897, W. Kuhlbrandt.

Photosynthesis 2: Energy conversion and electron conduction in soft matter Electron flow in photosynthesis of cyanobacteria H+ ADP ATP cytoplasm Q/QH2/Q hn ATPase bc1 RC LH-II LH-I periplasm e- H+ cytochrome c2 Electron flow in photosynthesis of purple bacteria

Role of Thermal Disorder on Electron Transfer in the Photosynthetic Reaction Center is coupled to the thermal motion of the surrounding protein.

Particle – Hole Separation in the Reaction Center and Solar Cells protein protein rotated – 900 and stretched

Cytochrome c2 docking hn H+ ADP ATP cytoplasm Q/QH2/Q ATPase bc1 RC LH-II LH-I periplasm e- H+ cytochrome c2

Photosynthetic Apparatus of Purple Bacteria Very Large Conformational Changes Qo 2Fe2S e- cyt c1 two path- ways for oxidation of Qo site Iron Sulfur Protein head rotation can redirect 2nd electron Sergei Izrailev

Photosynthetic Apparatus of Purple Bacteria Very Large Conformational Changes F1 rotatory catalysis (twist conformational change ATP synthesis ) F1 s t a l k (from Wang & Oster) elastomechanical coupling F0 ATP synthase energy transformation (proton motive force rotation) (Walker, Whilce, Fillingame) www.ks.uiuc.edu

Photosynthetic Pathway in Cyanobacteria and Plants

Electron Carrying Molecules bacterio- chlorophyll chain chain bacterio- pheophytin ubiquinone chain

Particle – Hole Separation in the Reaction Center and Solar Cells protein protein rotated – 900 and stretched

The energy gap is Gaussian distributed

Two State QM System Coupled to Protein Matrix First case: Coupling to a single oscillator Hamiltonian Protein matrix is a bath of oscillators linearly coupled to the electron transfer according to only a single oscillator considered at present!

Two State QM System Coupled to Protein Matrix Second case: Coupling to an ensemble of oscillators Hamiltonian Protein matrix is a bath of oscillators linearly coupled to the electron transfer according to

Electron Transfer Process Coupled to the Protein Matrix Rate for an ensemble of oscillators Relaxation rate But we don’t know all the coupling constants cj ? All we need to know is

Solution of Rate Equation

Electron Transfer Process Coupled to the Protein Matrix Rate for an ensemble of oscillators Relaxation rate But we don’t know all the coupling constants cj ? All we need to know is

Electron Transfer Process Coupled to the Protein Matrix Relaxation rate 1994 energy gap energy gap correlation function rms deviation of energy gap

Temperature Dependence of Electron Transfer Rate