Sutton H C
J Free Radic Biol Med. 1985;1(3):195-202. doi: 10.1016/0748-5514(85)90118-7.
The oxidation of formate to CO2 has been used to quantify . OH yields produced in oxygenated solutions by chelated iron salts reacting either directly with H2O2 in the Fenton reaction, or as catalysts in the Haber-Weiss reaction between H2O2 and radiolytically generated superoxide. This system involves a chain sequence since . OH regenerates O2- when producing CO2. Kinetic studies have been employed to show that catalysis by Fe-EDTA occurs by reduction of Fe3+-EDTA by O2- followed by its reoxidation by H2O2, and to show how O2- is ultimately consumed. At pH 7.3 more than 50 . OH radicals can be produced per molecule of Fe-EDTA and CO2 yields can exceed five per molecule of radiolytically generated O2-. Iron chelated with pyrophosphate, DTPA, citrate, ATP or ADP in phosphate or Tris buffer at pH 7.3 has less than 7% of the catalytic ability of Fe-EDTA (considerably less in most cases) even though all these ferrous chelates give appreciable yields of . OH in the Fenton reaction. Unchelated iron has no catalytic ability. Catalysis of the Haber-Weiss reaction in homogenous solution by iron salts, either free or chelated with nucleotides or citrate, is evidently a very inefficient process, and its possible role in superoxide toxicity must be viewed with these reservations.
甲酸氧化为二氧化碳已被用于量化在含氧溶液中由螯合铁盐产生的·OH产率，这些铁盐要么在芬顿反应中直接与过氧化氢反应，要么在过氧化氢与辐射产生的超氧化物之间的哈伯-维希反应中作为催化剂。由于·OH在产生二氧化碳时会再生O2-，所以该体系涉及一个链式反应序列。动力学研究已表明，Fe-EDTA的催化作用是通过O2-将Fe3+-EDTA还原，随后再被过氧化氢重新氧化来实现的，并且还展示了O2-最终是如何被消耗的。在pH 7.3时，每分子Fe-EDTA可产生超过50个·OH自由基，并且每分子辐射产生的O2-的二氧化碳产率可超过5个。在pH 7.3的磷酸盐或Tris缓冲液中，与焦磷酸盐、二乙三胺五乙酸（DTPA）、柠檬酸盐、三磷酸腺苷（ATP）或二磷酸腺苷（ADP）螯合的铁的催化能力不到Fe-EDTA的7%（在大多数情况下要低得多），尽管所有这些亚铁螯合物在芬顿反应中都能产生可观的·OH产率。未螯合的铁没有催化能力。铁盐（无论是游离的还是与核苷酸或柠檬酸盐螯合的）在均相溶液中对哈伯-维希反应的催化显然是一个非常低效的过程，其在超氧化物毒性中可能发挥的作用必须带着这些保留意见来看待。
