Binding of N-methyl isatin beta-thiosemicarbazone-copper complexes to proteins and nucleic acids.

N-Methyl isatin beta-thiosemicarbazone-copper complexes interact with nucleic acids and proteins as shown by ultraviolet (UV) and visible spectroscopy and Sephadex exclusion chromatography. The Cu++ ions are most effective; Co++ ions have less albeit significant activity. Chelating agents, such as Tris and histidine, high NaCl concentration, and dimethyl sulfoxide reduce the binding of the drug-metal complex. The binding constant of the drug-copper complex to calf-thymus DNA was calculated to range between 6.9 x 10(4) and 2.7 x 10(5) M-1.