[Interaction of caffeine with basic nucleic acids my a molecular mechanic method]

To understand some aspects of the biological action of caffeine (CAF), the interaction energies for various mutual positions of CAF and DNA bases or basepairs were calculated. Three types of mutual CAF-base (CAF-basepair) arrangements corresponding to the minima of interaction energy were revealed. One type of minima correspond to the stacking arrangement of molecules. This type is important for interactions of CAF with DNA monomers and single-stranded fragments. The other two types of minima correspond to the formation of intermolecular hydrogen bonds. Some of these minima may occur during the interaction of CAF with the double helix. One of these types corresponds to the nearly in-plane position of molecules. The other type of minima correspond to the nearly perpendicular arrangement of molecule planes. The minima of the last type are supposed to be the most important for the interaction of CAF with the DNA duplex, and interaction energies for this type of minima have the most negative values.