The speed of sound in DNA

Abstract

SynopsisWe have used Brillouin scattering to determine the speed of sound in (and hence longitudinal modulus of) A-and B-DNA fibers. The speed of sound is very sensitive to the degree of hydration of the fibers, and measurements have to be made at laser powers below 5 mW to avoid local heating and dehydration. Under those conditions, we obtain sound speeds perpendicular to the fiber axis of about 2.2 and 1.9 km/s in A-and B-DNA fibers, respectively. A-DNA fibers show a small anisotropy with sound speeds along the fiber axis higher by up to 10%. B-DNA fibers appear to be isotropic.

Base pair dynamic assisted charge transport in DNA

“…Such dynamical vibrations with periods as short as tens femtoseconds (i.e. phonons with ω ph ∼ 10 14 s −1 ) were reported in the literature [33][34][35]. Sincehω ph > T , occupation numbers of such phonons are small.…”

Electrical conductance in duplex DNA: Helical effects and low-frequency vibrational coupling

“…37,39 From basic physical principles one expects the acoustic modes will significantly affect the conductance at temperatures below the Debye temperature, which measures the temperature above which all modes begin to be excited, and below which modes begin to be progressively inactive. By assuming a speed of sound in B-DNA form of 1900 ms −1 , 40 and a lattice constant of approximately 0.34 nm, the Debye temperature was estimated as ⌰ D Ӎ 166 K for longitudinal compression modes. 37 On the other hand, specific heat measurements of biological DNA samples over the temperature range 0.5-5 K suggest significant smaller values ͑⌰ D Ӎ 20− 40 K͒ for torsional modes.…”

Nonlinear dynamics of topological solitons in DNA

“…The dependence of the sound velocity v 0 in the homogeneous molecule αβ =AT (GC) on the energy of rotation ǫ is presented in the Table II. According to different estimations [38,39,40] Table II it is clear, that among three typical values ǫ = 60, 600, 6000 kJ/mol the value ǫ = 6000 kJ/mol is the best one. Just this value will be used in the numerical investigations of the dynamics of topological solitons.…”