Chapter 7: Iron and Damage to Biomolecules

The most stable oxidation number of iron is ferric. Superoxide attack enzymes containing an iron-sulfur cluster, such as bacterial dihydroxyacid dehydratase, aconitase, or 6-phosphogluconate dehydrogenase. The search for cheap orally active alternatives to desferriox-amine has led to the development of a range of hydroxypyridone iron chelators. Hydroxypyridones can apparently remove iron ions from transferrin and lactoferrin, which are "safe" forms of iron unable to catalyze free-radical reactions. The importance of iron ions in mediating oxidative damage naturally leads to the question as to what forms of iron might be available to catalyze radical reactions in vivo. Bleomycin-detectable iron has also been measured in human sweat, in some cerebrospinal fluid samples, in synovial fluid from human knee joints, and in extracts of several bacterial strains. The ability of lactoferrin to resist damage by oxidants generated at sites of inflammation is consistent with such a role.