Transfer of copper between bis(thiosemicarbazone) ligands and intracellular copper-binding proteins. Insights into mechanisms of copper uptake and hypoxia selectivity

Abstract

Bis(thiosemicarbazonato) complexes CuII(Btsc) have attracted interest as promising metallodrugs and, in particular, as copper radiopharmaceuticals. Prototypes Cu(Atsm) and Cu(Gtsm) are membrane-permeable, but their metabolisms in cells are distinctly different: copper that is delivered by Cu(Gtsm) is trapped nonselectively in all cells, whereas copper that is delivered by Cu(Atsm) is retained selectively in hypoxic cells but is "washed out" readily in normal cells. We have studied copper-transfer reactions of these two complexes under various conditions, aiming to model their cellular chemistry. In Me2SO, both complexes exhibited reversible one-electron-reduction processes with Cu(Atsm) bein..