Watt G D, Burns A, Lough S, Tennent D L
Biochemistry. 1980 Oct 14;19(21):4926-32. doi: 10.1021/bi00562a035.
The MoFe protein from Azotobacter vinelandii undergoes a six-electron oxidation by various organic dye oxidants with full retention of initial activity. Reduction of the oxidized protein by S2O42- and by controlled potential electrolysis indicates the presence of two reduction regions at -290 and -480 mV, each requiring three electrons for complete reaction. Control of the oxidation conditions provides a means for preparing two distinct MoFe protein species selectively oxidized by three electrons. Selective reduction of the redox region at -290 mV causes development of the EPR signal associated with fully reduced MoFe protein while reduction at -480 mV produces a change in the visible spectrum but has no effect on the EPR signal intensity. Kinetic differences for reduction of the two redox regions indicate that the cofactor region undergoes a more rapid reaction with reductant than the other metal redox sites.
来自棕色固氮菌的钼铁蛋白可被各种有机染料氧化剂进行六电子氧化，且初始活性完全保留。用连二亚硫酸根（S2O42-）以及通过控制电位电解对氧化后的蛋白进行还原，结果表明在-290 mV和-480 mV处存在两个还原区域，每个区域完全反应都需要三个电子。对氧化条件的控制提供了一种制备两种不同的、被选择性氧化三电子的钼铁蛋白物种的方法。在-290 mV处对氧化还原区域进行选择性还原会导致与完全还原的钼铁蛋白相关的电子顺磁共振（EPR）信号出现，而在-480 mV处还原则会使可见光谱发生变化，但对EPR信号强度没有影响。两个氧化还原区域还原的动力学差异表明，辅因子区域与还原剂的反应比其他金属氧化还原位点更快。
