Iron(II) Supramolecular Helicates Condense Plasmid DNA and Inhibit Vital DNA-Related Enzymatic Activities
The dinuclear iron(II) supramolecular helicates [Fe2L3]Cl-4 (L= C25H20N4) bind to DNA through noncovalent (i. e., hydrogen-bonding, electrostatic) interactions and exhibit antimicrobial and anticancer effects. In this study, we show that the helicates condense plasmid DNA with a much higher potency than conventional DNA-condensing agents. Notably, molecules of DNA in the presence of the M enantiomer of [Fe2L]Cl-4 do not form intermolecular aggregates typically formed by other condensing agents, such as spermidine or spermine. The helicates inhibit the activity of several DNA-processing enzymes, such as RNA polymerase, DNA topoisomerase I, deoxyribonuclease I, and site-specific restriction endonucleases. However, the results also indicate that the DNA condensation induced by the helicates does not play a crucial role in these inhibition reactions. The mechanisms for the inhibitory effects of [Fe2L3]Cl-4 helicates on DNA-related enzymatic activities have been proposed.