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Efficiency of interacting molecular motors František Slanina slanina@fzu.cz fzu.cz/~slanina

Efficiency of interacting molecular motors František Slanina slanina@fzu.cz www.fzu.cz/~slanina. Brownian motion. Maxwell d e mon. Heats hot. Cools cold. Smoluchows ki r atchet. Granular r atchet. Feynman r atchet. On-off ratchet. Thermal ratchet. Pump: rocking ratchet.

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Efficiency of interacting molecular motors František Slanina slanina@fzu.cz fzu.cz/~slanina

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  1. Efficiency of interacting molecular motorsFrantišek Slanina slanina@fzu.cz www.fzu.cz/~slanina

  2. Brownian motion

  3. Maxwell demon Heats hot Cools cold

  4. Smoluchowski ratchet

  5. Granular ratchet

  6. Feynman ratchet

  7. On-off ratchet

  8. Thermal ratchet

  9. Pump: rocking ratchet

  10. Quantum ratchet

  11. Muscles

  12. cytoskeleton

  13. cytoskeletal traffic

  14. Cell division

  15. myosin dynein kinesin

  16. Hand-over-hand mechanism

  17. Neurons

  18. Ribosomes ASEP (B.Derrida)

  19. RNA polymerase „traffic jams“ „Christmass tree“

  20. Membrane tubes „traffic jam“

  21. “reversible” ratchet Spatial periodicity Temporal periodicity

  22. Potential Hopping probabilities Measured: expedited absorbed

  23. Without interaction

  24. (full) (empty)

  25. With interaction

  26. Gained efficiency

  27. At strong interaction

  28. Response

  29. Response

  30. Mean-field approximation Step I: “stroboscopic trick” Time within period which period Position within period Many hops per unit time Time-independent rates Time-independent master equation

  31. Mean-field Step II: effective potential MF1 MF2 or: effective hopping probability Poisson distribution parameter

  32. Mean-field or: effective hopping probability MF3

  33. Recursion: first step For calculation of On condition particle at x On condition two particles at x

  34. Recursion: second step For calculation of On condition particles at x and y Recursion: and so on…

  35. Mean-field MF1

  36. Comparison of MF schemes MF2 MF1 simulation MF3

  37. Phase diagram Non-optimizable phase MF1 MF1 simulation optimizable phase

  38. Work distribution g = 0.12 g = 0

  39. Energy balance current efficiency energy input

  40. Large deviations Fluctuation theorem? l.d.f.

  41. Conclusions • Efficiency increased by not too strong interaction • Current reversals when interaction and/or density increases • Energetic, rather than entropic effect • Complex behavior of response • Large deviations: non-Gaussian Outlook • Realistic model of myosin V • Clarify fluctuation symmetries Thanks: GAČR No. 202/07/0404

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