INRA, University of Avignon, UMR408, F-84000 Avignon, France.
Free Radic Biol Med. 2010 May 1;48(9):1162-72. doi: 10.1016/j.freeradbiomed.2010.01.037. Epub 2010 Feb 1.
Metmyoglobin (MbFe(III)), a major form of dietary iron, is an efficient inducer of lipid and protein oxidation. Indeed, MbFe(III) is able to cleave hydrogen peroxide and lipid hydroperoxides with subsequent formation of ferrylmyoglobin (MbFe(IV)=O) and lipid oxyl and peroxyl radicals. In the first part of this work, the mechanism of the reaction between MbFe(III) and H(2)O(2) is revisited with an emphasis on the influence of bovine serum albumin (BSA). BSA does not affect the rate of MbFe(IV)=O formation but inhibits the formation of a redox-inactive green pigment (heme-protein cross-link species). Although tightly bound to BSA, the flavonol quercetin is still able to reduce MbFe(IV)=O as a likely result of long-range electron transfers within a protein-protein complex. In the second part, BSA is shown to strongly slow down the metmyoglobin-catalyzed consumption of linoleic acid hydroperoxides with formation of ketones as the main products. In the process, only low concentrations of ferrylmyoglobin are slowly accumulated. A catalytic mechanism is proposed that involves a one-electron-oxidized metmyoglobin species distinct from ferrylmyoglobin.
高铁肌红蛋白（MbFe(III)）是膳食铁的主要形式，它是一种有效的脂质和蛋白质氧化诱导剂。事实上，MbFe(III)能够切割过氧化氢和脂质过氧化物，随后形成高铁肌红蛋白（MbFe(IV)=O）和脂质氧自由基和过氧自由基。在这项工作的第一部分中，我们重新研究了 MbFe(III)和 H(2)O(2)之间的反应机制，重点强调了牛血清白蛋白（BSA）的影响。BSA 不会影响 MbFe(IV)=O 形成的速率，但会抑制还原失活的绿色色素（血红素-蛋白质交联物质）的形成。尽管与 BSA 紧密结合，但类黄酮槲皮素仍然能够还原 MbFe(IV)=O，这可能是由于蛋白质-蛋白质复合物内的长程电子转移。在第二部分中，我们发现 BSA 强烈减缓了高铁肌红蛋白催化的亚油酸氢过氧化物的消耗，酮是主要产物。在这个过程中，只有低浓度的高铁肌红蛋白缓慢积累。我们提出了一种催化机制，其中涉及一种不同于高铁肌红蛋白的单电子氧化的高铁肌红蛋白物质。
