Biopolymers and cell. 1994. Volume 10. № 1. 82 - 89

V. A. Sorokin, V. A. Valeev, G. 0. Gladchenko, Yu. P. Blagoi, L. F. Sukhodub

INTERACTION BETWEEN ANTIMICROBIC ETHONIUM DRUG AND NATURAL DNA

Summary

    The interaction between the antimicrobic Ethonium drug and the natural DNA is revealed using the methods of differential UV spectroscopy and thermal denaturation. At low concentrations (~10~6—10~5 M) Ethonium increases thermal stability of DNA due to the interaction of bisquarternary nitrogens with the DNA phosphates. Besides, Ethonium is bound to the DNA bases, leading to the formation of single-chain disordered regions and their transition into a compact form consisting of particles with Ref ~ ~100 A. The nucleotide selectivity of Ethonium binding to the rc-DNA bases shows up as Ethonium-caused preferential destabilization of AT-pairs. At Ethonium concentrations (0,75—1)-10-4 M the differences in thermostabilities of AT- and GC-pairs are so large that the helix-coil transition in DNA becomes a two-phase one.