Interaction of DNA with Benzocrown Derivatives of Actinocin.

Complexes of DNA with actinocin derivatives containing benzocrown groups at positions 1 and/or 9 of the chromophore were studied by spectrophotometric titration and circular dichroism. The actinocin chromophore and the crown fragments are the DNA-binding sites of the ligands. The mode of ligand–DNA binding is shown to depend on the size of the crown group, its distance to the actinocin chromophore, and the ionic strength of the medium. Na⁺-selective benzocrown fragments combine with DNA phosphate groups. The simultaneous interaction of the actinocin chromophore with the DNA bases is possible only at an optimal distance between the two binding sites of ligand molecule. [ABSTRACT FROM AUTHOR]