This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.103044v1 92/11/3804    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lindén, M. Articles by Wallin, M. Search for Related Content PubMed PubMed Citation Articles by Lindén, M. Articles by Wallin, M.

Dwell Time Symmetry in Random Walks and Molecular Motors

Department of Theoretical Physics, Royal Institute of Technology (KTH), Stockholm, Sweden

Correspondence: Address reprint requests to M. Lindén, E-mail: linden{at}kth.se.

The statistics of steps and dwell times in reversible molecular motors differ from those of cycle completion in enzyme kinetics. The reason is that a step is only one of several transitions in the mechanochemical cycle. As a result, theoretical results for cycle completion in enzyme kinetics do not apply to stepping data. To allow correct parameter estimation, and to guide data analysis and experiment design, a theoretical treatment is needed that takes this observation into account. In this article, we model the distribution of dwell times and number of forward and backward steps using first passage processes, based on the assumption that forward and backward steps correspond to different directions of the same transition. We extend recent results for systems with a single cycle and consider the full dwell time distributions as well as models with multiple pathways, detectable substeps, and detachments. Our main results are a symmetry relation for the dwell time distributions in reversible motors, and a relation between certain relative step frequencies and the free energy per cycle. We demonstrate our results by analyzing recent stepping data for a bacterial flagellar motor, and discuss the implications for the efficiency and reversibility of the force-generating subunits.

This article has been cited by other articles:

				H. Qian Cooperativity and Specificity in Enzyme Kinetics: A Single-Molecule Time-Based Perspective Biophys. J., July 1, 2008; 95(1): 10 - 17. [Abstract] [Full Text] [PDF]