dorsal/arxiv
View SchemaDwell time symmetry in random walks and molecular motors
| Authors | Martin Lindén, Mats Wallin |
|---|---|
| Categories | |
| ArXiv ID | q-bio/0612026 |
| URL | https://arxiv.org/abs/q-bio/0612026 |
| DOI | 10.1529/biophysj.106.103044 |
| Journal | Biophys. J. 92(11): 3804-3816 (2007) |
Abstract
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 paper, 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. Key words: motor proteins; single molecule kinetics; enzyme kinetics; flagellar motor; Markov process; non-equilibrium fluctuations.
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"abstract": "The statistics of steps and dwell times in reversible molecular motors differ\nfrom those of cycle completion in enzyme kinetics. The reason is that a step is\nonly one of several transitions in the mechanochemical cycle. As a result,\ntheoretical results for cycle completion in enzyme kinetics do not apply to\nstepping data. To allow correct parameter estimation, and to guide data\nanalysis and experiment design, a theoretical treatment is needed that takes\nthis observation into account. In this paper, we model the distribution of\ndwell times and number of forward and backward steps using first passage\nprocesses, based on the assumption that forward and backward steps correspond\nto different directions of the same transition. We extend recent results for\nsystems with a single cycle and consider the full dwell time distributions as\nwell as models with multiple pathways, detectable substeps, and detachments.\nOur main results are a symmetry relation for the dwell time distributions in\nreversible motors, and a relation between certain relative step frequencies and\nthe free energy per cycle. We demonstrate our results by analyzing recent\nstepping data for a bacterial flagellar motor, and discuss the implications for\nthe efficiency and reversibility of the force-generating subunits. Key words:\nmotor proteins; single molecule kinetics; enzyme kinetics; flagellar motor;\nMarkov process; non-equilibrium fluctuations.",
"arxiv_id": "q-bio/0612026",
"authors": [
"Martin Lind\u00e9n",
"Mats Wallin"
],
"categories": [
"q-bio.BM",
"cond-mat.stat-mech",
"physics.bio-ph"
],
"doi": "10.1529/biophysj.106.103044",
"journal_ref": "Biophys. J. 92(11): 3804-3816 (2007)",
"title": "Dwell time symmetry in random walks and molecular motors",
"url": "https://arxiv.org/abs/q-bio/0612026"
},
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