THE IRON-SELECTIVE CHELATOR DESFERAL CAN REDUCE CHELATED COPPER

It was shown that the iron-selective chelator desferal (desferrioxamin e mesylate: DFO) can reduce Cu(II) as judged by measuring the formatio n of the complex between Cu(I) and a specific chelator for this specie s, neocuproine (NC), in phosphate buffer. It was found that under opti mal conditions, 3 moles of Cu(II) could be reduced per mole of DFO. St udies of the kinetics of Cu(II) reduction by DFO revealed that the rat e of Cu(II) reduction by DFO was considerably slower than that by asco rbate. In the case of both reductants, even in the absence of NC, Cu(I ) complexes remained in aqueous solutions for at least 30 min. DFO cou ld also reduce Cu complexed to histidine. The results presented highli ght the interpretive dangers which can arise in studies involving mult iple transition metals, especially in the presence of multiple chelato rs. Specifically, when desferal is used, it is important to be aware t hat any copper present may become reduced, and that any Cu(I) formed m ight participate in ongoing redox reactions.