Blumenfeld L A, Burbaev D S, Davydov R M, Kubrina L N, Vanin A F, Vilu R O
Biochim Biophys Acta. 1975 Feb 27;379(2):512-6. doi: 10.1016/0005-2795(75)90158-0.
The reduction of adrenal ferredoxin (adrenodoxin) at low temperatures was investigated in order to separate local modifications of the active centre of the protein on its reduction, from the conformational transition which seems to accompany the change of the redox state of the irons; The ESR spectra of the states of the protein, where the reduced active centre is to be found by the "oxidized" conformation of the apoprotein, were obtained. The transition from the states of the protein to the state which occurs on its chemical reduction at room temperature was also investigated. The results of the work support the view that conformational changes in proteins (enzymes) which take place while they are functioning proceed after modifications of the active centres (change of the redox state, adsorption of a substrate, etc.), and are essentially caused by them. Adrenal ferredoxin was the third subject in our studies of the intermediate states of proteins which appear after reduction of their active centres by means of electrons trapped in water-ethylene glycol mixtures at the temperature of liquid nitrogen [1, 2]. In the reduced state, the active centre of the protein has an ESR signal with a g-factor of 1.94 [3, 4] which is convenient for our purposes.
为了将蛋白质活性中心在还原时的局部修饰与似乎伴随铁氧化还原状态变化的构象转变区分开来，研究了低温下肾上腺铁氧化还原蛋白（肾上腺皮质铁氧还蛋白）的还原过程；获得了蛋白质状态的电子自旋共振（ESR）光谱，在该状态下，通过脱辅基蛋白的“氧化”构象可以找到还原的活性中心。还研究了蛋白质状态向其在室温下化学还原时所发生状态的转变。这项工作的结果支持这样一种观点，即蛋白质（酶）在发挥功能时发生的构象变化是在活性中心修饰（氧化还原状态变化、底物吸附等）之后进行的，并且基本上是由这些修饰引起的。肾上腺铁氧化还原蛋白是我们对蛋白质中间状态研究的第三个对象，这些中间状态是在液氮温度下通过捕获在水 - 乙二醇混合物中的电子还原其活性中心后出现的[1,2]。在还原状态下，蛋白质的活性中心具有g因子为1.94的ESR信号[3,4]，这对我们的研究目的很方便。
