Generation of *OH initiated by interaction of Fe2+ and Cu+ with dioxygen; comparison with the Fenton chemistry.
نویسندگان
چکیده
UNLABELLED Iron and copper toxicity has been presumed to involve the formation of hydroxyl radical (*OH) from H2O2 in the Fenton reaction. The aim of this study was to verify that Fe2+-O2 and Cu+-O2 chemistry is capable of generating *OH in the quasi physiological environment of Krebs-Henseleit buffer (KH), and to compare the ability of the Fe2+-O2 system and of the Fenton system (Fe2+ + H2O2) to produce *OH. The addition of Fe2+ and Cu+ (0-20 microM) to KH resulted in a concentration-dependent increase in *OH formation, as measured by the salicylate method. While Fe3+ and Cu2+ (0-20 microM) did not result in *OH formation, these ions mediated significant *OH production in the presence of a number of reducing agents. The *OH yield from the reaction mediated by Fe2+ was increased by exogenous Fe3+ and Cu2+ and was prevented by the deoxygenation of the buffer and reduced by superoxide dismutase, catalase, and desferrioxamine. Addition of 1 microM, 5 microM or 10 microM Fe2+ to a range of H2O2 concentrations (the Fenton system) resulted in a H2O2-concentration-dependent rise in *OH formation. For each Fe2+ concentration tested, the *OH yield doubled when the ratio [H2O2]:[Fe2+] was raised from zero to one. IN CONCLUSION (i) Fe2+-O2 and Cu+-O2 chemistry is capable of promoting *OH generation in the environment of oxygenated KH, in the absence of pre-existing superoxide and/or H2O2, and possibly through a mechanism initiated by the metal autoxidation; (ii) The process is enhanced by contaminating Fe3+ and Cu2+; (iii) In the presence of reducing agents also Fe3+ and Cu2+ promote the *OH formation; (iv) Depending on the actual [H2O2]:[Fe2+] ratio, the efficiency of the Fe2+-O2 chemistry to generate *OH is greater than or, at best, equal to that of the Fe2+-driven Fenton reaction.
منابع مشابه
Generation of OH initiated by interaction of Fe and Cu with dioxygen; comparison with the Fenton chemistry
Iron and copper toxicity has been presumed to involve the formation of hydroxyl radical ( . OH) from H2O2 in the Fenton reaction. The aim of this study was to verify that Fe 2+ -O2 and Cu + -O2 chemistry is capable of generating . OH in the quasi physiological environment of Krebs-Henseleit buffer (KH), and to compare the ability of the Fe 2+ -O2 system and of the Fenton system (Fe 2+ + H2O2) t...
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ورودعنوان ژورنال:
- Acta biochimica Polonica
دوره 47 4 شماره
صفحات -
تاریخ انتشار 2000