IR-SPECTROSCOPIC STUDY OF Cu2+ ION INTERACTION WITH DNA IN AQUEOUS SOLUTIONS CONTAINING ADDITIONS OF 1,2-PROPANEDIOL AND GLYCEROL

Abstract

The present work studied the Cu²⁺ ion interaction with DNA in aqueous solutions containing low (up to 20 v %) additions of glycerol or 1,2-propanediol at 29 and 45°C by IR-spectroscopy. Cu²⁺ ions were shown to induce the DNA transition into compact form in aqueous and water-glycerol (propanediol) solutions both at 29 and at 45°C. This process is of high positive cooperativity. 1,2-propanediol added to the DNA aqueous solution increases cooperativity of the DNA transition into compact state and decreases the Cu²⁺ ions concentration required to induce DNA compactisation. The 1,2-propanediol effect increases moriotonously with the rise of its volume concentration (in the concentration range 0-20 v %) at 29 and 45°C. In contrast to propanediol, the glycerol effect on DNA compactisation is of non-monotonous character: small (4 v %) glycerol additions to DNA aqueous solution decrease cooperativity of the DNA transition into compact state at 29°C. Comparison of effects of small additions of 1,2-propanediol and glycerol for which dielectric permeability of solution changes practically the same, on the Cu²⁺-induced DNA condensation, permits the conclusion that the DNA condensation induced by the Cu²⁺ ions depends not only on dielectric permeability but on the structure of the solution formed.