DNA-scission activities of ascorbate in the presence of metal chelates.

A systematic comparison of the DNA-scission activities of various transition metal ions and their metal chelates in the presence of reducing agents has been made. L-Ascorbate in combination with metal ions possesses a much higher scission activity as compared to sulfhydryl-containing reductants despite its low reduction potential. It is demonstrated that DNA-scission activities of metal complexes in the presence of various reducing agents is a general phenomenon for all transition metal ions albeit with different degrees of efficiency. The different reactivities of various metal complexes appear to be attributed, in part, to the differences in their redox electrochemical potentials of the reactions between metal chelates and the reducing agents. Agarose gel electrophoresis coupled with the determination of acid-soluble radioactivity from 3H-labeled DNA provides a rapid qualitative and quantitative assay for the comparison of the reactivities of different metal ions or metal chelates in combination with reductants on the DNA-scission reactions.