The CD of ligand-DNA systems. 2. Poly(dA-dT) B-DNA.
A systematic theoretical study of the CD of [poly(dA-dT)]2 and its complexes with achiral small molecules is presented. The CD spectra of [poly(dA-dT)]2 and of poly(dA):poly(dT) are calculated for various DNA structures using the matrix method. The calculated and experimental spectra agree reasonably well for [poly(dA-dT)]2 but less well for poly(dA):poly(dT). The calculated CD spectrum of [poly(dA-dT)]2 fails to reproduce the wavelength region of 205-245 nm of the experimental spectrum. This discrepancy can be explained by a magnetic dipole allowed transition contributing significantly to the CD spectrum in this region. The induced CD of a transition moment of a molecule bound to [poly(dA-dT)]2 is also calculated. As was the case for [poly(dG-dC)]2, the induced CD of a groove bound molecule is one order of magnitude stronger than that of an intercalated molecule. The calculations also show considerable differences between pyrimidine-purine sites and purine-pyrimidine sites. Both signs and magnitudes of the CD induced into ligands bound in the minor groove agree with experimental observations.
Lyng
R
R
Department of Physical Chemistry, Chalmers University of Technology, Gothenburg, Sweden.
Rodger
A
A
Nordén
B
B
D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D008024:Ligands; D011067:Poly dA-dT / Q000737:chemistry*
D008024:Ligands; D011067:Poly dA-dT; D004247:DNA