Sutton H C, Winterbourn C C
Arch Biochem Biophys. 1984 Nov 15;235(1):106-15. doi: 10.1016/0003-9861(84)90259-5.
Traces of iron, when complexed with either EDTA or diethylenetriaminepentaacetic acid (DTPA), catalyze an OH.-producing reaction between H2O2 and paraquat radical (PQ+.): H2O2 + PQ+.----PQ++ + OH. + OH-.[1]. Kinetic studies show that oxidation of formate induced by this reaction occurs by a Fenton-type mechanism, analagous to that assumed in the metal-catalyzed Haber-Weiss reaction, in which the rate determining step is H2O2 + Fe2+ (chelator)----Fe3+(chelator) + OH. + OH-,[7]; with k7 = 7 X 10(3) M-1 s-1 for EDTA and 8 X 10(2) M-1 s-1 for DTPA at pH 7.4. PQ+. rapidly reduces both Fe3+ (EDTA) and Fe3+ (DTPA), and hence allows both agents to catalyze [1] with comparable efficiency, in contrast to the much lower efficiency reported for the latter as a catalyst for the Haber-Weiss reaction. The catalytic properties of these chelating agents is attributed to their lowering of E0 (Fe3+/Fe2+) by 0.65 V, thus making [7] thermodynamically possible at pH 7. Approximately 2.5% of the OH. produced is consumed by internal or "cage" reactions, which decompose the chelator and produce CO2; however, the majority (97%) diffuses into the bulk solution and participates in competitive reactions with OH. scavengers.
铁的痕迹与乙二胺四乙酸（EDTA）或二乙烯三胺五乙酸（DTPA）络合时，会催化过氧化氢与百草枯自由基（PQ +.）之间产生羟基自由基（OH - ）的反应：H2O2 + PQ +.→PQ ++ + OH. + OH - [1]。动力学研究表明，该反应诱导的甲酸氧化通过芬顿型机制发生，类似于金属催化的哈伯 - 韦斯反应中假设的机制，其中速率决定步骤是H2O2 + Fe2 +（螯合剂）→Fe3 +（螯合剂）+ OH. + OH - [7]；在pH 7.4时，EDTA的k7 = 7×10³ M⁻¹ s⁻¹，DTPA的k7 = 8×10² M⁻¹ s⁻¹。与报道的后者作为哈伯 - 韦斯反应催化剂的效率低得多相反，PQ +.能迅速还原Fe3 +（EDTA）和Fe3 +（DTPA），因此使这两种试剂以相当的效率催化反应[1]。这些螯合剂的催化特性归因于它们将E0（Fe3 + / Fe2 +）降低了0.65 V，从而使反应[7]在pH 7时在热力学上成为可能。产生的OH - 中约2.5%被内部或“笼”反应消耗，这些反应会分解螯合剂并产生CO2；然而，大多数（97%）扩散到本体溶液中，并与OH - 清除剂参与竞争反应。
