IR-SPECTROSCOPIC STUDIES OF DIVALENT METAL-ION EFFECTS ON DNA HYDRATION

The metal (Mn2+, Ca2+, Cu2+) ion effect on the DNA structure in films is studied at different relative humidities (5-98%) by IR-spectroscopy . The results obtained suggest the interaction of the ions both with t he DNA phosphate groups and with the nucleic bases. The formation of t he secondary structure of DNA complexed with metal ions is shown to ta ke place at a greater number of water molecules bound to the polymer t han it is the case of DNA without ions. The interaction of DNA with me tal ions inhibits its transition into the A form and induces essential changes in the hydration energy. (C) 1997 Elsevier Science B.V.