Binding of carbon monoxide to isolated hemoglobin chains.
Binding of carbon monoxide to isolated hemoglobin chains.
复制标题
一氧化碳与分离的血红蛋白链的结合。
DOI：
10.1021/bi00594a007
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发表时间：
1978
期刊：
影响因子：
2.9
通讯作者：
L. Sorensen
中科院分区：
文献类型：
--
作者：
N. Alberding;S. S. Chan;L. Eisenstein;H. Frauenfelder;D. Good;I. C. Gunsalus;T. Nordlund;M. Perutz;A. H. Reynolds;L. Sorensen
结合一氧化碳的血红蛋白的分离的α和β链，有和没有结合的对-汞苯甲酸，已被测量在温度从5至340 K的时间2 μ s至1 ks使用闪光光解。所有四种蛋白质都表现出三种不同的再结合过程。的数据进行解释的模型中，一氧化碳，从溶剂中的亚铁血红素铁的结合位点，遇到三个障碍。这三个过程的温度依赖性产生的三个障碍的所有四种蛋白质的激活熵和熵。结合在温度低于约200 K是非指数的，这意味着最内层的障碍有一个分布的激活hysteries。四种蛋白质的分布已被确定。在低于30 K的温度下，CO的结合率接近有限的低温极限，从而通过量子力学隧道结合。通过建立一个简单的模型，从测量的隧穿率中提取了最内层势垒的宽度。实验参数与血红蛋白链的结构特征，并与以前发表的肌红蛋白和血红素的数据进行比较。最内层势垒的高度和平衡CO压力之间建立了相关性。
Binding of carbon monoxide to the separated alpha and beta chains of hemoglobin, with and without bound p-mercuribenzoate, has been measured at temperatures from 5 to 340 K for times 2 mus to 1 ks using flash photolysis. All four proteins exhibit three different rebinding processes. The data are interpreted by a model in which the carbon monoxide, moving from the solvent to the binding site at the ferrous heme iron, encounters three barriers. The temperature dependences of the three processes yield activation enthalpies and entropies for the three barriers for all four proteins. Binding at temperatures below about 200 K is nonexponential, implying that the innermost barrier has a distribution of activation enthalpies. The distributions for the four proteins have been determined. At temperatures below 30 K, the CO binding rates approach finite low-temperature limits; binding thus proceeds by quantum-mechanical tunneling. Invoking a simple model, the widths of the innermost barriers are extracted from the measured tunneling rates. The experimental parameters are correlated with structural features of the hemoglobin chains and compared with previously published data on myoglobin and protoheme. A correlation is established between the height of the innermost barrier and the equilibrium CO pressure.