MONTE-CARLO SIMULATIONS OF THE INTERACTION BETWEEN THE DODECANUCLEOTIDE D(CAATCCGGATTG)(2) AND TRIS(ETHYLENEDIAMINE)COBALT(III) CATIONS

The interaction between a synthetic DNA dodecanucleotide and tris(ethy lenediamine)cobalt(III) cations has been studied by Monte Carlo simula tions. A simple two-state model with a single adjustable parameter is used to model the H-1-NMR chemical shift movements obtained in a paral lel experimental study of the metal-ion complex-dodecamer interaction. The observed chemical shift movements, due to changes in the metal-io n complex and electrolyte concentrations, are quantitatively reproduce d by this model. The simulations indicate that the binding of the Delt a-enantiomer of tris(ethylenediamine)cobalt(III) cation can be mainly attributed to electrostatic forces. Furthermore, the results suggest t hat the enantiomeric selectivity observed in the experimental study ca n be explained in terms of a suitable complementarity of hydrogen-bond donors on the metal-ion complex with hydrogen-bond accepters on the d odecamer.