27 research outputs found
Force and kinetic barriers in unzipping of DNA
A theory of the unzipping of double-stranded (ds) DNA is presented, and is
compared to recent micromanipulation experiments. It is shown that the
interactions which stabilize the double helix and the elastic rigidity of
single strands (ss) simply determine the sequence dependent =12 pN force
threshold for DNA strand separation. Using a semi-microscopic model of the
binding between nucleotide strands, we show that the greater rigidity of the
strands when formed into dsDNA, relative to that of isolated strands, gives
rise to a potential barrier to unzipping. The effects of this barrier are
derived analytically. The force to keep the extremities of the molecule at a
fixed distance, the kinetic rates for strand unpairing at fixed applied force,
and the rupture force as a function of loading rate are calculated. The
dependence of the kinetics and of the rupture force on molecule length is also
analyzed.Comment: Revtex file + 6 eps Figures; published in Proc. Natl. Acad. Sci. USA
98, 8608 (2001
Nanomechanical measurements of the sequence-dependent folding landscapes of single nucleic acid hairpins
[(C6H5)3P]2Ni(Me3Si?C?C?SiMe3). Darstellung, Eigenschaften und Struktur des ersten stabilen Nickel(0)-Komplexes von Bis-trimethylsilylacetylen
Molecular sorting by stochastic resonance
To sort a targeted species from a mixture, we introduce a procedure that relies on the enhancement of its effective diffusion coefficient. We use the formation of a host–guest complex between α-cyclodextrin and a dye to evidence the dye dispersion when the medium is submitted to an oscillating field. In particular, we demonstrate that the effective diffusion coefficient of the dye may be increased far beyond its intrinsic value by tuning the driving field frequency in the stochastic resonance regime. We use this effect to selectively sort from a mixture a dye that is addressed by its rate constants for association with α-cyclodextrin