Measurement of work in single-molecule pulling experiments

A main goal of single-molecule experiments is to evaluate equilibrium free energy differences by applying fluctuation relations to repeated work measurements along irreversible processes. We quantify the error that is made in a free energy estimate by means of the Jarzynski equality when the accumul...

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Bibliographic Details
Published in:The Journal of chemical physics 2009-06, Vol.130 (23), p.234116-234116-10
Main Authors: Mossa, Alessandro, de Lorenzo, Sara, Huguet, Josep Maria, Ritort, Felix
Format: Article
Language:English
Subjects:
Computer Simulation
Models, Chemical
Thermodynamics
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Summary:A main goal of single-molecule experiments is to evaluate equilibrium free energy differences by applying fluctuation relations to repeated work measurements along irreversible processes. We quantify the error that is made in a free energy estimate by means of the Jarzynski equality when the accumulated work expended on the whole system (including the instrument) is erroneously replaced by the work transferred to the subsystem consisting of the sole molecular construct. We find that the error may be as large as 100%, depending on the number of experiments and on the bandwidth of the data acquisition apparatus. Our theoretical estimate is validated by numerical simulations and pulling experiments on DNA hairpins using optical tweezers.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.3155084