Influence of DNA-binding on the photochromic equilibrium of a chromene derivative

Abstract

The photochromic properties of a chromene derivative, which contains a positively charged substituent, were investigated in the presence of ct DNA. Upon irradiation in the absence of DNA the colored quinoid open form is highly unstable and rapidly reverts back to the initial closed form (bleaching). In the presence of DNA the open form is significantly stabilized, presumably because of the association with the macromolecule. The kinetics of the bleaching reaction of the bound ligand were determined and employed to estimate the binding constant.