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Proceedings Paper

Optical tweezers as a tool of precision: single-molecule mobility as case study
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Paper Abstract

We present a procedure for a precise power spectral analysis of optical tweezers data. This procedure uses the entire frequency range of the experimental power spectrum. We apply this procedure to experimental data from a biological system, data for the motion of a microsphere attached with a biotin-streptavidin linker to a single protein, the λ-receptor of E. coli. As in [Oddershede et al, Biophys. J. 83, 3152 (2002)] and [Oddershede et al, J. Phys.: Condens. Mat. 15, S1737 (2003)], we find that the λ-receptor moves diffusively in the outer membrane, but is confined to a particular region by a harmonic potential. Here, we show that since the power spectrum is known with precision up to its Nyquist frequency of 8 kHz, one can resolve the relative motion of the λ-receptor and the microsphere attached to it. We find that the biotin-streptavidin link between them can be described as a Hookean spring. Since we can see only the microsphere, these results are based on an interpretation of the power spectrum of its motion. This interpretation is based on a model. We use the simplest model that is necessary and sufficient to interpret the power spectrum in its full range. This model fits the spectrum well and the fit yields the model's parameters with some precision. These results indicate that optical tweezers have the potential to become a tool of precision. We discuss improvements of experiments and analysis that are necessary in order to realize this potential.

Paper Details

Date Published: 1 July 2004
PDF: 11 pages
Proc. SPIE 5322, Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues II, (1 July 2004); doi: 10.1117/12.528813
Show Author Affiliations
Kirstine Berg-Sorensen, Niels Bohr Institute (Denmark)
Lene Oddershede, Niels Bohr Institute (Denmark)
Henrik K. Flyvbjerg, Riso National Lab. (Denmark)

Published in SPIE Proceedings Vol. 5322:
Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues II
Dan V. Nicolau; Joerg Enderlein; Robert C. Leif; Daniel L. Farkas, Editor(s)

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