The simultaneous measurement of the decrease of available Fe(II) ions and the increase of available Fe(III) ions allowed the analysis of the ferroxidase activity of two distinct apoferritins. Although recombinant human apoferritin (HuFtH) rapidly oxidizes Fe(II) to Fe(III) , this iron is not properly stored in the ferritin cavity, as otherwise occurs in horse-spleen H/L-apoferritin (HsFt; H=heavy subunit, L=light subunit). Iron storage in these apoferritins was also studied in the presence of two copper-loaded mammalian metallothioneins (MT2 and MT3), a scenario that occurs in different brain-cell types. For HuFtH, unstored Fe(III) ions trigger the oxidation of Cu-MT2 with concomitant Cu(I) release. In contrast, there is no reaction with Cu-MT2 in the case of HsFt. Similarly, Cu-MT3 does not react during either HuFtH or HsFt iron reconstitution. Significantly, the combination of ferritin and metallothionein isoforms reported in glia and neuronal cells are precisely those combinations that avoid a harmful release of Fe(II) and Cu(I) ions.
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机译：同时测量可用的Fe（II）离子的减少和可用的Fe（III）离子的增加，可以分析两种不同的载铁蛋白的铁氧化酶活性。尽管重组人载铁蛋白（HuFtH）迅速将Fe（II）氧化为Fe（III），但该铁并未正确存储在铁蛋白腔中，否则会在马脾H / L-铁蛋白（HsFt; H =重亚基， L ＝轻亚基）。还研究了在两种载铜的哺乳动物金属硫蛋白（MT2和MT3）的存在下在这些载铁蛋白中的铁存储，这种情况发生在不同的脑细胞类型中。对于HuFtH，未存储的Fe（III）离子会触发Cu-MT2的氧化，同时释放Cu（I）。相反，在HsFt的情况下，与Cu-MT2没有反应。同样，在HuFtH或HsFt铁重构过程中，Cu-MT3也不会发生反应。重要的是，神经胶质细胞和神经元细胞中报道的铁蛋白和金属硫蛋白同工型的组合正是避免有害释放Fe（II）和Cu（I）离子的那些组合。
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