Liochev S I, Fridovich I
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
IUBMB Life. 1999 Aug;48(2):157-61. doi: 10.1080/713803492.
Superoxide (O2-) poses multiple threats, which are diminished by a family of metalloenzymes, the superoxide dismutases. Among the damaging effects of O2- are direct oxidation of low-molecular-weight reductants; inactivation of a select group of enzymes; and reaction with NO to yield the strong oxidant, peroxynitrite. Of even greater import is the ability of O2- to univalently oxidize the [4 Fe-4 S] clusters of dehydratases, which causes release of iron. The "free" iron, which is kept reduced by cellular reductants, then reduces hydroperoxides to hydroxyl or alkoxyl radicals. Because the "free" iron will preferentially bind to anionic polymers, such as nucleic acids, or to anionic surfaces, such as cell membranes, these radicals will be generated adjacent to these vital targets and will preferentially attack them. O2- and iron can thus be viewed as partners in crime, and reciprocal regulatory effects between iron and O2- may be anticipated. These are discussed.
超氧阴离子（O2-）会造成多种威胁，而一类金属酶——超氧化物歧化酶可减轻这些威胁。O2-的破坏作用包括对低分子量还原剂的直接氧化；使一组特定的酶失活；以及与一氧化氮反应生成强氧化剂过氧亚硝酸盐。更重要的是，O2-能够单电子氧化脱水酶的[4Fe-4S]簇，导致铁释放。被细胞还原剂保持还原状态的“游离”铁，随后将氢过氧化物还原为羟基或烷氧基自由基。由于“游离”铁会优先结合到阴离子聚合物（如核酸）或阴离子表面（如细胞膜）上，这些自由基将在这些重要靶点附近产生，并优先攻击它们。因此，O2-和铁可被视为犯罪同伙，可以预期铁和O2-之间会产生相互调节作用。本文将对此进行讨论。
