Martsinkiavichene I A, Chenas N K, Kulis Iu Iu, Usanov S A
Biokhimiia. 1990 Sep;55(9):1624-31.
The diaphorase activity of NADPH: adrenodoxin reductase (EC 1.18.1.2) is stimulated by adrenodoxin. The latter prevents the reductase inhibition by NADPH; the Line-weaver-Burk plots are characterized by a biphasic dependence of the reaction rate on the oxidizer concentration. At pH 7.0 the maximal rate of the first phase is 20s-1; that for the second phase at saturating concentrations of adrenodoxin is 5 s-1. Since the second phase rate is equal to that of the adrenodoxin-linked cytochrome c reduction by reductase it is concluded that this phase reflects the reduction of the oxidizers via reduced adrenodoxin. Quinones are reduced by adrenodoxin in an one-electron way; the logarithms of their rate constants depend hyperbolically on their single-electron reduction potentials (E7(1]. The oxidizers interact with a negatively charged domain of adrenodoxin. The depth of the adrenodoxin active center calculated from the Fe(EDTA)- reduction data is 5.9 A.
肾上腺皮质铁氧化还原蛋白还原酶（EC 1.18.1.2）的黄递酶活性受肾上腺皮质铁氧化还原蛋白的刺激。后者可防止还原酶被NADPH抑制；Line - weaver - Burk图的特征是反应速率对氧化剂浓度呈双相依赖性。在pH 7.0时，第一相的最大速率为20s⁻¹；在肾上腺皮质铁氧化还原蛋白饱和浓度下，第二相的最大速率为5s⁻¹。由于第二相速率与还原酶介导的肾上腺皮质铁氧化还原蛋白连接的细胞色素c还原速率相等，因此得出结论，该相反映了通过还原型肾上腺皮质铁氧化还原蛋白对氧化剂的还原作用。醌类通过肾上腺皮质铁氧化还原蛋白以单电子方式被还原；它们速率常数的对数与其单电子还原电位（E7(1]）呈双曲线关系。氧化剂与肾上腺皮质铁氧化还原蛋白的一个带负电荷的结构域相互作用。根据Fe(EDTA)还原数据计算出的肾上腺皮质铁氧化还原蛋白活性中心深度为5.9埃。
