A Postulated Primitive Photosystem That Generates Atp in Fluctuating Light
نویسنده
چکیده
2 I. INTRODUCTION II. PHOTOSYSTEM 0: THE MECHANISM 1. Fluctuating Light 2. Formation of Metastable Dipoles (a) Light-induced RC Dipoles and their Metastability (b) Distance Traversed within the RC by the Excited or Separated Electron (c) Number of Separated Electrons per RC (d) Contrast 3. The Photosynthetic Dipole Potential (a) The Dipole Potential (b) Surface Area per RC (c) Relative Dielectric Constant of the Membrane and the RC (d) Estimated Values 4. ATPsynthase (a) Single Mode and Conduction (b) Two Different Modes (c) Flexible Coupling (d) Local Coupling 5. The Photosystem 0 Cycle III. EVOLUTION MODEL FOR PHOTOSYNTHESIS 1. The Evolution of ATPsynthase 2. The Thermosystem (a) The Thermosystem and the Reaction Center (b) Power (c) Chlorophylls 3. From Thermosystem to Photosystem 0 (a) Intramolecular Charge Separation (b) Intermolecular Charge Separation (c) PS0 Diversification (d) Power 4. From Photosystem 0 to Standard Photosynthesis (a) Quinone Diffusion (b) Photosystem Combination; Addition of the bc 1 Complex (c) Power IV. PHOTOSYSTEM 0 AND THE CHLOROPLAST 1. The Relations between Light Intensity, Membrane Potential, Redox State of ATPsynthase and the Q-cycle (a) Mode changes (b) The Q-cycle 2. Combined PS0/PS Activity 3. Combined MTS/PS0/PS Activity (a) Dipole Potentials (b) Effects of Different Constant Temperatures (c) Effects of a Cyclically Varying Temperature 4. Possible Relics of MTS/PS0 Activity (a) Special Reactions (b) Etiolation (c) Stacking and Swelling (d) Induction (e) Chloroplast Oscillations (f) State 1-State 2 Transitions V. DISCUSSION VI. CONCLUSION ACKNOWLEDGMENTS REFERENCES
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Photosystem 0 , a proposed ancestral photosystem without reducing power that synthesized ATP during light - dark cycling
Photosystem 0 concerns a primitive mechanism for free energy gain as ATP from fluctuating light during early evolution. The PS0 reaction centers had no reducing power: charge transport was only temporary. Light induced within the reaction centers metastable dipoles that generated a membrane potential. This in turn drove ATP synthesis by protons moving through the ATP synthase enzyme. After the ...
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