SPECIFIC CATIONS (К+, Na+) EFFECT ON THE THERMODYNAMIC BINDING PARAMETERS OF ACTINOCINE DERIVATIVES WITH DNA MOLECULE

E.B. Moroshkina, T.A. Urusova

St Petersburg State University, Russia, 198504, St Petersburg, Ul’aynovskaya, 1. evmorosh@mail.ru

Failures in Na-K-exchange in cells accompany a number of diseases including some oncology diseases. In this connection, one of the ways to produce anti-tumor drugs is a synthesis of compounds of which binding features with DNA depend on counter-ion origin in solution. At the St Petersburg Technology University (Institute of Technology), the derivatives of different heterocyclic compounds with crown-groups, which associate К+ and Na+ ions [1], were synthesized. Heterocyclic chromophore of such compounds is able to intercalate into DNA double helix, and the crown-groups interact electrostatically with phosphate groups of polynucleotide chain [2].
 Involving the methods of spectrophotometric and polarimetric titration, this work treats the thermodynamic binding parameters of actinocine derivatives containing radicals –benzo(15-crown-5),   –benzo(18-crown-6), or alkyl-amino-alkil groups in amid groups. Measurements are carried out in water-salt solutions of different ionic strength, containing К+ or Na+ ions.
These studies results in finding the higher values of binding constants and number of binding sites per pair of nucleotides of all the actinocine derivatives under investigation, the К+ ions being presented instead of Na+ ions, under condition of equal ionic strength of a medium with no influence of positively charged group origin in amid groups. This result can testify on better ability of Na+ ions to screen the DNA phosphate groups in solution as compared with К+ ions.
In the case of compounds including radicals –benzo(15-crown-5), the differences in values of binding parameters are more pronounced and involved by a change in their binding mode with DNA molecule under changing in counter-ion origin in solution. The work discusses an eventual dependence of binding mode of these compounds on their confirmation in solutions containing К+ or Na+ ions.
The results obtained give a possibility to treat the actinocine derivatives containing radicals –benzo(15-crown-5) as the potential specific anti-tumor preparations.

REFERENCES

[1] E.N. Glibin, D.V. Ovchinnikov, N.G. Plechanova. Russ. J. Org. Chem. 33 (1997) 1494.
[2]  E.B. Moroshkina. Vestnik SPbGU, Ser. 4 (2007) Issue 2, 17.