[Theoretical investigation on the hypochromism of dinucleoside phosphates]

The hypochromism of stacked dimers of the nucleotide bases taken as models of the dinucleoside phosphates and dinucleotides was studied with the use of the configuration interaction and pertubation theory methods. General expression for the hypochromism of the polynucleotides is given in the first order perturbation theory with three different ways for approximation of the matrix elements of the perturbation operator. This expression was used for calculation of the dimer hypochromism in terms of theoretically calculated monomer characteristics. Dependence of the hypochromism on the dimer conformation was investigated. The results obtained so far demonstrate that it is important to take into account the electronic transitions in the vacuum UV region. This approach will enable one to elucidate the contribution of neighbouring bases into the DNA hypochromism.