Calculation of Far Infrared Absorption in B Poly(dA).poly)(dT)

摘要

We calculate the far infrared absorption of B conformation poly(dA) poly(dT), using eigenvectors from a lattice dynamical model refined with the latest inelastic neutron scattering data. Our various calculations include the isolated helix, the addition of counterions, and the addition of a 'spine of hydration' in the minor groove. We find agreement with experimental infrared data except for one mode. We then attempt to model a coupling between two helices and show some evidence that this mode is interhelical. Since our initial prediction of vibrational modes in deoxyribonucleic acid DNA in the 1-100 reciprocal centimeters frequency range, several experimental groups have used Brillouin, low frequency Raman, and infrared absorption measurements to study this region of the spectrum. Resonant rather than dissipative modes have been observed and in one case the lifetime of such a mode has been determined. In addition to this new Raman and infrared data, inelastic neutron scattering data is also now available. This neutron data is of particular interest to us as it has allowed refinement of our model of he long range nonbonded interactions in DNA.