Treffry A, Hirzmann J, Yewdall S J, Harrison P M
Krebs Institute for Biomolecular Research, Department of Molecular Biology, University of Sheffield, UK.
FEBS Lett. 1992 May 11;302(2):108-12. doi: 10.1016/0014-5793(92)80417-f.
Recombinant H chain ferritins bearing site-directed amino acid substitutions at their ferroxidase centres have been used to study the mechanism of catalysis of Fe(II) oxidation by this protein. UV-difference spectra have been obtained at various times after the aerobic addition of Fe(II) to the recombinants. These indicate that the first product of Fe(II) oxidation by wild type H chain apoferritin is an Fe(III) mu-oxo-bridged dimer. This suggests that fast oxidation is achieved by 2-electron transfer from two Fe(II) to dioxygen. Modelling of Fe(III) dimer binding to human H chain apoferritin shows a solvent-accessible site, which resembles that of ribonucleotide reductase in its ligands. Substitution of these ligands by other amino acids usually prevents dimer formation and leads to greatly reduced Fe(II) oxidation rates.
在其铁氧化酶中心带有定点氨基酸取代的重组H链铁蛋白已被用于研究该蛋白质催化Fe（II）氧化的机制。在向重组体有氧添加Fe（II）后的不同时间获得了紫外差光谱。这些结果表明，野生型H链脱铁铁蛋白氧化Fe（II）的第一个产物是Fe（III）μ-氧桥联二聚体。这表明通过从两个Fe（II）到双氧的双电子转移实现了快速氧化。Fe（III）二聚体与人H链脱铁铁蛋白结合的模型显示出一个溶剂可及的位点，其在配体方面类似于核糖核苷酸还原酶的位点。用其他氨基酸取代这些配体通常会阻止二聚体形成并导致Fe（II）氧化速率大大降低。
