DNA bifunctional intercalators. 1. Synthesis and conformational properties of an ethidium homodimer and of an acridine ethidium heterodimer

Abstract

An ethidium homodimer and an acridine ethidium heterodimer were synthesized. The ethidium and the acridine chromophore were introduced in such bifunctional intercalators in order to allow the fluorometric study of the interaction of such molecules with DNA, which is reported in the companion paper (Gaugain, et al. (1978)). In the preparation of the acridine-ethidium dimer, acetyl groups are used as new protecting agents in the phenanthridine series. Conformational studies of the dimers by visible absorption and NMR spectroscopy indicate that they exist in equilibrium between folded and unfolded conformations; this equilibrium is pH and temperature dependent. Models for the geometry of the folded forms are proposed.