Gergerich J, Millett F
Hoppe Seylers Z Physiol Chem. 1981 Nov;362(11):1533-7. doi: 10.1515/bchm2.1981.362.2.1533.
The importance of electrostatic interactions to the reaction between cytochrome c and cytochrome c oxidase is indicated most directly by the rapid increase in Km as ionic strength is increased. However, Chessa et al. (1980, Hoppe-Seyler's Z. Physiol. Chem. 361, 1077--1091) have recently found that a cytochrome c derivative trifluoroacetylated at all 19 lysine amino groups decreased the reaction rate between ferrocytochrome c and cytochrome c oxidase nearly as much as native ferricytochrome c, a known inhibitor that binds cytochrome c oxidase. They suggested that this was due to the formation of an inhibitory complex between trifluoroacetyl-cytochrome c and cytochrome c oxidase, which would argue against the importance of electrostatic interactions to the native complex. We have demonstrated that this apparent inhibition is in fact caused by a rapid electron transfer between native ferrocytochrome c and trifluoroacetyl-ferricytochrome c which decreases the concentration of native ferrocytochrome c, thus decreasing the reaction rate.
随着离子强度增加，Km迅速上升，这最直接地表明了静电相互作用对细胞色素c与细胞色素c氧化酶之间反应的重要性。然而，切萨等人（1980年，《霍佩-赛勒生理化学杂志》361卷，1077 - 1091页）最近发现，一种在所有19个赖氨酸氨基上都被三氟乙酰化的细胞色素c衍生物，使亚铁细胞色素c与细胞色素c氧化酶之间的反应速率降低的程度，几乎与天然高铁细胞色素c（一种已知的能结合细胞色素c氧化酶的抑制剂）相同。他们认为这是由于三氟乙酰化细胞色素c与细胞色素c氧化酶之间形成了抑制性复合物，这似乎与静电相互作用对天然复合物的重要性相悖。我们已经证明，这种明显的抑制实际上是由天然亚铁细胞色素c与三氟乙酰化高铁细胞色素c之间的快速电子转移引起的，这种转移降低了天然亚铁细胞色素c的浓度，从而降低了反应速率。
