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Theory for rates, equilibrium constants, and Brønsted slopes in F_1-ATPase single molecule imaging experiments

Volkán-Kacsó, Sándor and Marcus, Rudolph A. (2015) Theory for rates, equilibrium constants, and Brønsted slopes in F_1-ATPase single molecule imaging experiments. Proceedings of the National Academy of Sciences of the United States of America, 112 (46). pp. 14230-14235. ISSN 0027-8424. PMCID PMC4655567.

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A theoretical model of elastically coupled reactions is proposed for single molecule imaging and rotor manipulation experiments on F_1-ATPase. Stalling experiments are considered in which rates of individual ligand binding, ligand release, and chemical reaction steps have an exponential dependence on rotor angle. These data are treated in terms of the effect of thermodynamic driving forces on reaction rates, and lead to equations relating rate constants and free energies to the stalling angle. These relations, in turn, are modeled using a formalism originally developed to treat electron and other transfer reactions. During stalling the free energy profile of the enzymatic steps is altered by a work term due to elastic structural twisting. Using biochemical and single molecule data, the dependence of the rate constant and equilibrium constant on the stall angle, as well as the Brønsted slope are predicted and compared with experiment. Reasonable agreement is found with stalling experiments for ATP and GTP binding. The model can be applied to other torque-generating steps of reversible ligand binding, such as ADP and Pi release, when sufficient data become available.

Item Type:Article
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URLURL TypeDescription CentralArticle
Marcus, Rudolph A.0000-0001-6547-1469
Additional Information:© 2015 National Academy of Sciences. Contributed by Rudolph A. Marcus, September 17, 2015 (sent for review August 25, 2015; reviewed by Attila Szabo and Arieh Warshel). Published online before print October 19, 2015. We thank Drs. Long Cai, Attila Szabo, David Thirumulai, and Arieh Warshel for their helpful comments. The authors would like to acknowledge support from the Office of the Naval Research, the Army Research Office, and the James W. Glanville Foundation.
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
Army Research Office (ARO)UNSPECIFIED
James W. Glanville FoundationUNSPECIFIED
Subject Keywords:biomolecular motors; free energy relations; ATPase; single molecule imaging; Brønsted slope
Issue or Number:46
PubMed Central ID:PMC4655567
Record Number:CaltechAUTHORS:20151021-130628918
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Official Citation:Sándor Volkán-Kacsó and Rudolph A. Marcus Theory for rates, equilibrium constants, and Brønsted slopes in F1-ATPase single molecule imaging experiments PNAS 2015 112 (46) 14230-14235; published ahead of print October 19, 2015, doi:10.1073/pnas.1518489112
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61385
Deposited By: Tony Diaz
Deposited On:21 Oct 2015 20:47
Last Modified:23 Apr 2020 23:53

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