Berlin 2005 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 100: Poster Session I
AKB 100.32: Poster
Samstag, 5. März 2005, 16:45–18:45, Poster TU D
Conformations of worm-like chains in nanotubes — •Frederik Wagner1, Gianluca Lattanzi2, and Erwin Frey1 — 1Abteilung Theorie, Hahn-Meitner-Institut Berlin — 2Physics Department, University of Bari
The conformations of polymers in a confining medium is not only a challenging problem in soft matter physics but also of great practical relevance. One ambitious goal is to localize transcription factors to a specific binding site on DNA which would require to confine DNA to structures smaller or at least comparable to its persistence length, ℓp≈50 nm. In recent experimental setups [1] DNA was successfully confined to channels down to 35 nm×35 nm size.
These recent developments ask for a theoretical investigation of the statistical conformations of stiff polymers (e.g. DNA or F-Actin) in confining environments like tubes and channels. We have developed an off-lattice Monte-Carlo simulation as well as analytical approximations in the weakly-bending rod limit to arrive at a scaling relation for the (apparent) mean-square end-to-end distance ⟨ R2⟩. All Monte-Carlo data are found to collapse on an universal scaling curve as a function of the ratio between persistence length ℓp and Odijk’s deflection length ℓd. For fixed geometry this scaling plot can serve as a gauge in translating the experimental measured values into the real contour length L.
Three different scaling regimes are identified: the free polymer regime, an intermediate regime following de Gennes’ ‘blob’ picture and — for strongly confined or stiff polymers — an Odijk scaling regime.
[1] Tegenfeldt, J. O. et al. Proc. Natl. Acad. Sci. 101, 10979 (2004)