Faraggi M, Klapper M H
Department of Chemistry, Nuclear Research Centre-Negev, Beer-Sheva, Israel.
Biochem Biophys Res Commun. 1990 Jan 30;166(2):867-72. doi: 10.1016/0006-291x(90)90890-y.
The single sulfhydryl group (Cys-50) of the methemerythrin from Phascolosoma gouldii reacts with 5,5'dithiobis(2-nitrobenzoic acid) to form a mixed disulfide. The pulse radiolytically generated formate radical reduces this mixed disulfide to its radical anion. In turn, the disulfide radical anion reduces the protein two-iron center over a nominal distance of 13 A. The rate constant for this intramolecular electron transfer is approximately 15 s-1 at room temperature, pH 7. Between the two redox centers there is an equilibrium driving force of 0.78 V, measured by differential pulsed polarography.
来自古氏星虫的高铁血红蛋白的单个巯基（Cys-50）与5,5'-二硫代双（2-硝基苯甲酸）反应形成混合二硫键。脉冲辐射产生的甲酸根自由基将这种混合二硫键还原为其自由基阴离子。反过来，二硫键自由基阴离子在约13埃的标称距离上还原蛋白质的双铁中心。在室温、pH 7条件下，这种分子内电子转移的速率常数约为15 s-1。通过差分脉冲极谱法测得，两个氧化还原中心之间的平衡驱动力为0.78 V。
