Light-dependent reduction of copper(II) and its effect on cell-mediated, thiol-dependent superoxide production.

The thiol-dependent reduction of copper(II) and associated superoxide radical production in copper(II)-treated cultures of the unicellular alga Dunaliella tertiolecta is induced by light of wavelength greater than 425 nm. We propose that the effect of light on these reactions is mediated at the copper(II) reduction step through a light-stimulated ligand to metal charge transfer reaction between sulphur and copper(II). These results suggest that light may be an important controlling factor in metal-induced lipid peroxidation reactions.