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Stepping statistics in molecular motors - lessons from simple models
  KTH/Nordita/SU seminar in Theoretical Physics [before December 2013]

Wednesday 11 April 2007
from 13:00 to 14:00
at FB55
Speaker : Martin Lindén (KTH)
Abstract : Motor proteins are molecular motors that convert chemical energy, for example ATP or ions flow through a membrane potential, into mechanical work. Motor proteins play important roles in many cellular processes, such as intracellular transport, bacterial motility, or respiration. They are also interesting for future applications in nano technology, and from a physics point of view, as examples of non-equilibrium systems whose kinetics can be studies at the single molecule level. To understand in detail how different motor proteins work has proven a major challenge. Theoretical modelling of the statistical properties of single molecule data, for example from trapping experiments where single motors step along molecular tracks, is one possibility to gain further insight. We have studied the statistical properties of simple Markov models for stepping motor proteins, and come up with two interesting results. First, we have shown that steps and dwell times observed in stepping experiments can be correlated, even in very simple models. Second, we have derived a symmetry property for the waiting time distributions in reversible motors, that can be used to extract the free energy per cycle directly from stepping trajectories. To illustrate our results, we analyze recent stepping data from the bacterial flagellar motor, and discuss the implications for efficiency and reversibility for the force generating subunits.

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