【摘要】 应用亚铁螯合剂研究了棕色固氮菌固氮酶铁蛋白中Fe₄S4_簇与Mg·ATP的关系。未变性铁蛋白与螯合剂无反应。Mg·ATP和PCMB促进铁蛋白中的铁与螯合剂的反应。Mg·ADP抑制Mg·ATP的作用。加入Mg·ATP或PCMB后1小时内有75％以上的铁被螯合,20小时内几乎全部被螯合（97％以上）。单独的ATP,ADP,Mg⁺⁺无作用。氧钝化铁蛋白中铁能直接与螯合剂反应,Mg·ATP或PCMB浓度与反应速度的关系符合S型动力学。用Hill作图法得到斜率的为2,说明在铁被螯合前Fe₄S₄簇上（或附近）的两个位置已参与反应。Brdicka反应和羟甲基化作用结果表明钼铁蛋白与铁蛋白巯基二者的相互作用。更多还原

【Abstract】 The reaction between the ferrous iron chelator, 2, 2’ -dipyridyl, and the iron-sulfur cluster in iron protrin of nitrogenase from Azotobacter vinelandii has beenstudied. This reaction was greatly accelerated in the presence of MgATP andPCMB. Native iron protein was resistant to ferrous iron chelator and little ironwas complexed even after 20 hours. When MgATP or PCMB was added, however,> 75% of the iron reacted in the first hour and > 97% within 20 hours. Noeffect was seen with ATP, ADP or Mg²⁺ alone. Oxygen-damaged iron proteinreacted immediately with the chelating agent. Analysis of relationship betweenreaction rate and concentration of MgATP and PCMB revealed the sigmoidalkinetics. MgADP inhibited the initial rate of iron removal from the iron proteinby the chelator when in the presence of MgATP. A Hill plot of log （v/Vmax.-v） as a function of the logarithm of the MgATP or PCMB concentration gavea straight line with a slope of about 2.0, suggesting that a minimum of two sitesat or near Fe-S cluster must have been influenced before the iron of the iron proteinbecame accessible to the chelator. The results of Brdicka reaction and alkylationhave shown that the presence of the MoFe-protein protected the iron of the ironprotein from chelation and the sulfhydryl groups from alkylation, suggesting thatthe binding of MoFe-protein to Fe-protein was at or near the iron-sulfur clusterof the Fe-protein probably via the sulfhydryl groups.更多还原