Copper-ligand interactions and physiological free radical processes. pH-dependent influence of Cu2+ ions on Fe2(+)-driven OH. generation.
Prior to comparative studies on the reactivity of various copper complexes with respect to OH. radicals, the influence of free Cu2+ ions on the superoxide-independent generation of OH. radicals through Fenton assays and water gamma radiolysis has been tested in the present work. Cu2+ ions have been shown to behave in a distinct manner towards each of these two production systems. As was logically expected from the noninvolvement of copper in OH. radical production through gamma radiolysis, no influence of Cu2+ ions has been observed on the amount of radicals detected in that case. In contrast, Cu2+ ions do influence OH. radical generation through iron-driven Fenton reactions, but differently depending on copper concentration. When present in high concentrations, Cu2+ ions significantly contribute to OH. radical production, which confirms previous observations on the reactivity of these in the presence of hydrogen peroxide. At lower levels corresponding to copper/iron ratios below unity on the contrary, Cu2+ ions behave as inhibitors of the OH. production in a pH-dependent manner over the 1-6 range investigated: the lower the pH, the greater the inhibition. The possible origin of this previously unreported inhibitory effect is discussed.
Maestre
P
P
Laboratoire de Biochimie, Hôpital Purpan, Toulouse, France.
Lambs
L
L
Thouvenot
J P
JP
Berthon
G
G
D002851:Chromatography, High Pressure Liquid; D003300:Copper; D003497:Cyclic N-Oxides; D003855:Deoxyribose; D005609:Free Radicals; D005720:Gamma Rays; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides; D017665:Hydroxyl Radical; D006900:Hydroxylation; D007501:Iron; D008024:Ligands; D012459:Salicylates; D020156:Salicylic Acid; D013113:Spin Labels; D013481:Superoxides
D003497:Cyclic N-Oxides; D005609:Free Radicals; D006878:Hydroxides; D008024:Ligands; D012459:Salicylates; D013113:Spin Labels; D013481:Superoxides; D017665:Hydroxyl Radical; D003855:Deoxyribose; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D003300:Copper; D007501:Iron; D020156:Salicylic Acid