What is it about?
For over 4 decades hemoglobin was believed to be a biological Fenton reagent, behaving in an identical manner to simple iron chelators such as EDTA. This was a consequence of observed oxidations believed to be produced by hydroxyl radicals. These hydroxyl radicals were thought to be generated from the reaction of hemoglobin with hydrogen peroxide. However, the oxidations that were observed were in fact due to the generation of a strongly oxidizing iron (IV) ferryl species, and not due to hydroxyl radicals. There is some overlap in the oxidations that these two species can produce. However, there are a number of oxidations that are unique to the iron (IV) ferryl species.
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Why is it important?
The identification of the correct oxidizing species generated by heme or hemoglobin and hydrogen peroxide couples, more accurately accounts for the oxidations observed, and toxicity produce by these oxidizing couples. In addition, it points out the potential for the misinterpretation of the action of thiourea as a hydroxyl radical moper in systems that contain hydrogen peroxide and/or superoxide.
Perspectives
Since a number of manuscripts have based their conclusions on the erroneous belief that heme or hemoglobin and hydrogen peroxide generate hydroxyl radicals as a consequence of the initial paper devoted to this topic. Sadrzadeh SM, Graf E, Panter SS, Hallaway PE, Eaton JW. Hemoglobin: a biologic Fenton reagent. J Biol Chem 1984; 259(23):14354–6. The conclusions drawn in these manuscripts will need to be revised.
Dr Philip Gerard Penketh
Yale University
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This page is a summary of: Hemoglobin Is Not a Biological Fenton Reagent, Reactive Oxygen Species, March 2022, American Innovative Medical Sciences and Technologies (AIMSCI) Inc.,
DOI: 10.20455/ros.2022.c.801.
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