Change in the spatial packing of DNA molecules forming liquid crystalline microphases with change in the external conditions

Abstract

The authors have studied the circular dichroism spectra of LC microphases formed both from free DNA molecules and those which are complexed with anthracycline antibiotics in solutions of different acidity at different temperatures. The appearance of intense bands of circular dichroism in the region of absorption of the nitrogenous bases (chromophores) of DNA (λ≈270 nm) and the chromophores of the antibiotic (λ≈500 nm) and synchronous change in the amplitudes of both bands with change in the external conditions (pH, T) points to the presence of helical twisting of the LC microphases of DNA the direction of which is determined at the moment of formation of the microphases. The direction of helical twisting of the microphase changes with change in the energy of interaction between the DNA molecules as a result of the binding of the antibiotic or rise in the temperature of the solution.