Do Ternary DNA-Cr(III)-Small Molecule Adducts Form?

The carcinogenic and mutagenic properties of chromium(VI) complexes have been ascribed to the formation of ternary DNA-Cr(III)-small molecule adducts. However, in no case has a ternary adduct been directly characterized using spectroscopic techniques. As part of these laboratories' efforts to establish the structures and properties of discrete binary and ternary adducts of Cr(III) and DNA at a molecular level, an array of methods has been attempted unsuccessfully to generate ternary DNA-Cr(III)-small molecule adducts with ascorbate, cysteine, glutathione, dithiothreitol, and NADH. These studies along with an analysis of the strength of the interaction between Cr(III) and guanine and the importance of hydrogen bonding in the formation of binary DNA-Cr(III) adducts suggest that ternary DNA-Cr(III)-small molecule adducts may not form under biologically relevant conditions and that the adducts of small molecules and DNA may be solely organic in nature.