Study of effect of water on the interaction of DNA and actinocin derivatives with various aminoalkyl chain length by infrared spectrophotometry and computer modeling

A comparative study of the effect of water on the interaction of DNA with actinocin derivatives having different numbers of methylene groups in side chains was performed by IR spectroscopy. It was found that, as relative humidity increases, water molecules simultaneously bind to hydrate-active sites of DNA and ligands. The absorption band at v = 1137 cm-1, caused by oscillations of the C-O and P-O groups of atoms in the DNA-ligand complex having two methylene groups, is due to the interactions between the cationic groups of the ligand and the sugar-phosphate backbone of DNA, which may be one of the reasons for the high stability of this complex. Using computer simulation of interaction of DNA fragments and actinocin derivatives in water environment, molecular models of the formation of their complexes for two ways of binding were constructed.