Stretching a macromolecule in an atomic force microscope: Statistical mechanical analysis

Citation
Hj. Kreuzer et al., Stretching a macromolecule in an atomic force microscope: Statistical mechanical analysis, BIOPHYS J, 80(6), 2001, pp. 2505-2514
Citations number
14
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOPHYSICAL JOURNAL
ISSN journal
00063495 → ACNP
Volume
80
Issue
6
Year of publication
2001
Pages
2505 - 2514
Database
ISI
SICI code
0006-3495(200106)80:6<2505:SAMIAA>2.0.ZU;2-B
Abstract
We formulate the proper statistical mechanics to describe the stretching of a macromolecule under a force provided by the cantilever of an Atomic Forc e Microscope. In the limit of a soft cantilever, the generalized ensemble o f the coupled molecule-cantilever system reduces to the Gibbs ensemble for an isolated molecule subject to a constant force in which the extension is fluctuating. For a stiff cantilever, one obtains the Helmholtz ensemble for an isolated molecule held at a fixed extension with the force fluctuating. Numerical examples and predictions for experiments with cantilevers of dif fering stiffness are given for short and long chains of poly (ethylene glyc ol), based on parameter-free ab initio calculations.