Interactions of Ag~+ ions with DNA and its monomers

摘要

Different UV spectra of DNA and its monomers that were inducted by Ag~+ ions were measured, and the effect of ions on the parameters of the helix-coil transition was studied. The data obtained confirm the existence of strong and weak modes of binding of Ag~+ to DNA. The earlier proposed proton transfer from NIG to N3C, which is determined by the interaction of Ag~+ with N7G (a strong complex), follows immediately from the shape of the differential UV spectra. The positive cooperativity of the binding of Ag~+ to DNA upon the formation of a weak complex is due to the cooperativity of the transition of DNA to a new double-helical conformation. A model of this conformation is proposed which suggests the formation of Hougsteen GC and AT pairs.