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Transition paths in single-molecule force spectroscopy

Acceso Abierto
ID Minciencias: ART-0000681440-55
Ranking: ART-ART_A1

Abstract:

In a typical single-molecule force spectroscopy experiment, the ends of the molecule of interest are connected by long polymer linkers to a pair of mesoscopic beads trapped in the focus of two laser beams. At constant force load, the total extension, i.e., the end-to-end distance of the molecule plus linkers, is measured as a function of time. In the simplest systems, the measured extension fluctuates about two values characteristic of folded and unfolded states, with occasional transitions between them. We have recently shown that molecular (un)folding rates can be recovered from such trajectories, with a small linker correction, as long as the characteristic time of the bead fluctuations is shorter than the residence time in the unfolded (folded) state. Here, we show that accurate measurements of the molecular transition path times require an even faster apparatus response. Transition paths, the trajectory segments in which the molecule (un)folds, are properly resolved only if the beads fluctuate more rapidly than the end-to-end distance of the molecule. Therefore, over a wide regime, the measured rates may be meaningful but not the transition path times. Analytic expressions for the measured mean transition path times are obtained for systems diffusing anisotropically on a two-dimensional free energy surface. The transition path times depend on the properties both of the molecule and of the pulling device.

Tópico:

Force Microscopy Techniques and Applications

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Citations: 51
51

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Información de la Fuente:

SCImago Journal & Country Rank
FuenteThe Journal of Chemical Physics
Cuartil año de publicaciónNo disponible
Volumen148
Issue12
Páginas123309 - N/A
pISSNNo disponible
ISSN0021-9606

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