脱氧肌红蛋白对高铁肌红蛋白的还原作用：一种不涉及电子传递蛋白的蛋白质-蛋白质氧化还原反应。

Reduction of methemerythrin by deoxymyoglobin: a protein-protein redox reaction not involving electron-transfer proteins.

作者信息

Bradić Z, Harrington P C, Wilkins R G

出版信息

Biochemistry. 1979 Mar 6;18(5):889-93. doi: 10.1021/bi00572a024.

Abstract

The stoichiometry and kinetics of reaction of methemerythrin with the deoxy forms of myoglobin and hemoglobin have been examined at I = 0.2 M and 25 degrees C. One mole of methemerythrin (on the basis of the monomer unit containing two irons) reacts with 2 mol of deoxymyoglobin and with 0.5 mol of deoxyhemoglobin. All reactions are second order. Rate constants for reaction with deoxymyoglobin are 0.25 M-1s-1 (Phascolopsis gouldii) and 5.6 M-1s-1 (Themiste pyroides) at pH 6.3. There is little effect of raising the ionic strength to 1.35 M and only a small decrease in rate when the pH is adjusted to 8.2. The rate constant for reaction of deoxyhemoglobin with P. gouldii methemerythrin is approximately 0.1 M-1s-1 at pH 6.3. Metmyohemerythrin from T. pyroides reacts slightly slower than the octamer form (k = 2.0 M-1s-1 at pH 6.3 and 7.0). Oxymyoglobin is converted to metmyoglobin by methemerythrin. The electron-transfer path is discussed and a self-exchange rate constant for hemerythrin assessed as 10(-3) M-1s-1 on the basis of Marcus's theory.

摘要

在离子强度I = 0.2 M及25摄氏度条件下，对高铁肌红蛋白与肌红蛋白和血红蛋白的脱氧形式的反应化学计量学和动力学进行了研究。1摩尔高铁肌红蛋白（基于含两个铁原子的单体单元）与2摩尔脱氧肌红蛋白以及与0.5摩尔脱氧血红蛋白发生反应。所有反应均为二级反应。在pH 6.3时，与脱氧肌红蛋白反应的速率常数，对于古氏柱体虫（Phascolopsis gouldii）为0.25 M⁻¹s⁻¹，对于热液管虫（Themiste pyroides）为5.6 M⁻¹s⁻¹。将离子强度提高到1.35 M时影响很小，而将pH值调至8.2时反应速率仅略有下降。在pH 6.3时，脱氧血红蛋白与古氏柱体虫高铁肌红蛋白反应的速率常数约为0.1 M⁻¹s⁻¹。来自热液管虫的高铁肌红蛋白原的反应速度略慢于八聚体形式（在pH 6.3和pH 7.0时k = 2.0 M⁻¹s⁻¹）。高铁肌红蛋白可将氧合肌红蛋白转化为高铁肌红蛋白。文中讨论了电子转移途径，并根据马库斯理论评估了血色素蛋白的自交换速率常数为10⁻³ M⁻¹s⁻¹。