Dailey H A, Lascelles J
J Bacteriol. 1977 Feb;129(2):815-20. doi: 10.1128/jb.129.2.815-820.1977.
Membranes from Spirillum itersonii reduce ferric iron to ferrous iron with reduced nicotinamide adenine dinucleotide or succinate as a source of reductant. Iron reduction was measured spectrophotometrically at 562 nm using ferrozine, which chelates ferrous iron specifically. Reduced nicotinamide adenine dinucleotide or succinate was also effective as a source of iron. The effects of respiratory inhibitors suggested that reduction of iron occurs at one or more sites on the respiratory chain before cytochrome c. Reduction of iron and synthesis of protoheme with the physiological reductants were also observed with crude extracts of other bacteria, including Rhodopseudomonas spheroides, Rhodopseudomonas capsulata, Paracoccus denitrificans, and Escherichia coli. The effect of oxygen upon reduction of iron and formation of protoheme was examined with membranes from S. itersonii, using succinate as a source of reductant. Both systems were inhibited by oxygen, but this effect was completely reversed by addition of antimycin A. We conclude that reduced components of the respiratory chain serve as reductants for ferric iron, but with oxygen present they are oxidized preferentially by the successive members of the chain. This could be a mechanism for regulating synthesis of heme and cytochrome by oxygen.
来自迭代螺菌（Spirillum itersonii）的细胞膜能利用还原型烟酰胺腺嘌呤二核苷酸或琥珀酸作为还原剂将三价铁还原为二价铁。使用特异性螯合二价铁的亚铁嗪，在562nm波长处通过分光光度法测定铁的还原。还原型烟酰胺腺嘌呤二核苷酸或琥珀酸也可作为铁源发挥作用。呼吸抑制剂的作用表明，铁的还原发生在细胞色素c之前呼吸链的一个或多个位点。用包括球形红假单胞菌（Rhodopseudomonas spheroides）、荚膜红假单胞菌（Rhodopseudomonas capsulata）、反硝化副球菌（Paracoccus denitrificans）和大肠杆菌（Escherichia coli）在内的其他细菌的粗提物也观察到了用生理性还原剂进行的铁还原和原血红素的合成。以琥珀酸作为还原剂，用迭代螺菌的细胞膜研究了氧气对铁还原和原血红素形成的影响。两个系统均受氧气抑制，但加入抗霉素A后这种作用完全逆转。我们得出结论，呼吸链的还原成分作为三价铁的还原剂，但在有氧气存在时，它们会被呼吸链中的后续成员优先氧化。这可能是一种由氧气调节血红素和细胞色素合成的机制。
