Application of the continuous variation method to cooperative interactions: mechanism of Fe(II)-ferrozine chelation and conditions leading to anomalous binding ratios
Application of the continuous variation method to cooperative interactions: mechanism of Fe(II)-ferrozine chelation and conditions leading to anomalous binding ratios
复制标题
DOI：
10.1016/s0301-4622(02)00275-2
复制
发表时间：
2003-01-01
影响因子：
3.8
通讯作者：
Chock, PB
中科院分区：
文献类型：
--
作者：
Huang, CY;Zhou, RX;Chock, PB
连续变化法，通常被称为约伯图，长期以来一直用于确定两个相互作用组分的化学计量。当反应物C-o的总浓度远远大于所涉及的解离常数时，通常可以得到正确的结合比n。对于非合作结合体系，随着C-o的增加，化学计量在1和n之间变化；而对于正合作系统，在低C-o时可以观察到大于n的值。在本报告中，我们举了一些例子来说明作为C-o函数的表观化学计量的变化如何为区分各种结合机制提供线索。为了验证这些概念，我们研究了铁（II）与铁锌在C-o = 7至210 muM范围内的螯合作用，铁（II）以摩尔浓度或其结合当量（在本例中为3）表示。根据多个模型对结果进行了分析，发现最符合一步络合物形成或无限协同作用的机理，K-d为8 muM。@ 2002 Elsevier Science B.V.版权所有
The method of continuous variation, often known as the Job plot, has long been used for determining the stoichiometry of two interacting components. The correct binding ratio, n, is generally obtained when the total concentration of the reactants, C-o, is much greater than the dissociation constants involved. For non-cooperative binding systems, the stoichiometry varies between one and n as C-o increases; whereas for positive cooperative systems, values larger than n may be observed at low C-o. In this report, we present examples to illustrate how the changing apparent stoichiometries as a function of C-o can provide clues for differentiating various binding mechanisms. To test these concepts, we examined the chelation of Fe(II) with ferrozine in the range of C-o = 7 to 210 muM with Fe(II) expressed in molar concentration or in terms of its binding equivalents (three in this case). The results were analyzed according to several models and found to be most consistent with the mechanism of one-step complex formation or infinite cooperativity with a K-d of 8 muM. @ 2002 Elsevier Science B.V. All rights reserved.