Superior hydrolytic DNA cleavage by a dinuclear copper(II) N4S4-donor complex compared with a mononuclear N2S2-donor close analogue

The cleavage of plasmid DNA by a dinuclear copper(II) complex of 1,2,4,5-tetrakis(1′-amino-3′-thiabutyl)benzene is promoted significantly (rate constant of 3.3×10−5 s−1 at pH 7.8 and 37°C) compared with the essentially inactive mononuclear copper(II) complex of the analogue 1,2-bis(1′-amino-3′-thiabutyl)benzene (rate constant <10−10 s−1). This implies that the two copper ions in close proximity and acting synergetically are important in accelerating cleavage, and separate roles for the two coppers in the dimer are proposed.