Sedimentation velocity analysis of heterogeneous protein-protein interactions:: Sedimentation coefficient distributions c(s) and asymptotic boundary profiles from Gilbert-Jenkins theory
Sedimentation velocity analysis of heterogeneous protein-protein interactions:: Sedimentation coefficient distributions c(s) and asymptotic boundary profiles from Gilbert-Jenkins theory
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DOI：
10.1529/biophysj.105.059584
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发表时间：
2005-07-01
影响因子：
3.4
通讯作者：
Schuck, P
中科院分区：
文献类型：
--
作者：
Dam, J;Schuck, P
在快速结合平衡中的相互作用蛋白在外力的影响下表现出耦合迁移。在沉积中，双组分系统可以表现出双峰边界，由一个组分的一小部分种群的未受干扰的沉积和反应边界中自由和复杂物质的混合物的耦合沉积组成。对于无限时间后无扩散沉降的理论极限，Gilbert和Jenkins已经预测了反应边界的形状和沉降速度梯度。我们将这些渐近梯度与沉降系数分布c(s)进行比较，c(s)是通过直接模拟Lamm方程解的叠加从实验沉降剖面中提取的。整体形状在质量上是一致的，不同边界分量的振幅和重量平均s值在数量上是一致的。我们提出c(s)峰的面积和重量平均s值的浓度依赖性可以用基于Gilbert-Jenkins理论的等温线来模拟，为利用反应边界的双峰结构分析实验数据提供了一个可靠的方法。这可以显著提高对配合物的结合常数和流体动力学参数的估计。
Interacting proteins in rapid association equilibrium exhibit coupled migration under the influence of an external force. In sedimentation, two-component systems can exhibit bimodal boundaries, consisting of the undisturbed sedimentation of a fraction of the population of one component, and the coupled sedimentation of a mixture of both free and complex species in the reaction boundary. For the theoretical limit of diffusion-free sedimentation after infinite time, the shapes of the reaction boundaries and the sedimentation velocity gradients have been predicted by Gilbert and Jenkins. We compare these asymptotic gradients with sedimentation coefficient distributions, c(s), extracted from experimental sedimentation profiles by direct modeling with superpositions of Lamm equation solutions. The overall shapes are qualitatively consistent and the amplitudes and weight-average s-values of the different boundary components are quantitatively in good agreement. We propose that the concentration dependence of the area and weight-average s-value of the c(s) peaks can be modeled by isotherms based on Gilbert-Jenkins theory, providing a robust approach to exploit the bimodal structure of the reaction boundary for the analysis of experimental data. This can significantly improve the estimates for the determination of binding constants and hydrodynamic parameters of the complexes.