[Additional possibilities of the formation of incorrect nucleotide pairs]

Calculations of intermolecular interaction energies for the systems consisting of two nitrogen bases and one or two molecules of water have been performed by the atom--atom potential function method. In some energy minima corresponding to the arrangement of the bases with one of the bases being in the syn-orientation with respect to the sugar two bases are linked through one H-bond and one or two water bridges. Such pairs provide an additional possible pathway for the appearance of errors during template biosynthesis.