The Rules are Changing: Force Measurements on Single Molecules and How They Relate to Bulk Reaction Kinetics and Energies

Authors: Guthold, M.¹; Superfine, R.²; Taylor, R.M.³

Source: Biomedical Microdevices, Volume 3, Number 1, 1 March 2001 , pp. 9-18(10)

Publisher: Springer

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Abstract:

This paper addresses the question how to relate force measurements taken on individual molecules (force spectroscopy) to quantities that have been traditionally measured in bulk, such as the energies and rates of a reaction. For this purpose, two fundamentally different reactions need to be distinguished: Reactions that proceed at equilibrium and those that don't. In equilibrium reactions, an applied force induces a thermodynamic- ally reversible transformation and the free energy of the reaction can be extracted from single molecule force measurements. In non-equilibrium reactions, an applied force induces a thermodynamic- ally irreversible change and the dissociation rate can be extracted from single molecule force measurements. Thus, it is possible to extract thermodynamically relevant parameters from single molecule force measurements.

Keywords: force spectroscopy; atomic force microscopy (AFM); rupture force; dissociation rate; affinity; free enthalpy; single molecule

Document Type: Regular paper

Affiliations: 1: Department of Computer Science and Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 guthold@cs.unc.edu 2: Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 3: Department of Computer Science, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599

Publication date: 2001-03-01