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Toshiaki Miura, A mechanistic study of the formation of hydroxyl radicals induced by horseradish peroxidase with NADH, The Journal of Biochemistry, Volume 152, Issue 2, August 2012, Pages 199–206, https://doi.org/10.1093/jb/mvs068
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Abstract
During the oxidation of NADH by horseradish peroxidase (HRP-Fe3+), superoxide (O−2) is produced, and HRP-Fe3+ is converted to compound III. Superoxide dismutase inhibited both the generation of O−2 and the formation of compound III. In contrast, catalase inhibited only the generation of O−2. Under anaerobic conditions, the formation of compound III did not occur in the presence of NADH, thus indicating that compound III is produced via formation of a ternary complex consisting of HRP-Fe3+, NADH and oxygen. The generation of hydroxyl radicals was dependent upon O−2 and H2O2 produced by HRP-Fe3+-NADH. The reaction of compound III with H2O2 caused the formation of compound II without generation of hydroxyl radicals. Only HRP-Fe3+-NADH (but not K+O−2 and xanthine oxidase-hypoxanthine) was able to induce the conversion of metmyoglobin to oxymyoglobin, thus suggesting the participation of a ternary complex made up of HRP-Fe2+…O2…NAD. (but not free O−2 or H2O2) in the conversion of metmyoglobin to oxymyoglobin. It appears that a cyclic pathway is formed between HRP-Fe3+, compound III and compound II in the presence of NADH under aerobic conditions, and a ternary complex plays the central roles in the generation of O−2 and hydroxyl radicals.
