Measuring internal friction of an ultrafast-folding protein
Measuring internal friction of an ultrafast-folding protein
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DOI：
10.1073/pnas.0806154105
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发表时间：
2008-11-25
影响因子：
11.1
通讯作者：
Eaton, William A.
中科院分区：
文献类型：
--
作者：
Cellmer, Troy;Henry, Eric R.;Eaton, William A.
纳秒激光T-跳跃被用来测量粘度依赖性的绒毛子域的折叠动力学的条件下，粘度没有影响其平衡性能。的展开/重折叠弛豫时间对溶剂粘度的依赖性表示从内部摩擦的动力学的主要贡献。内摩擦随温度的升高而增加，表明过渡态沿着反应坐标向具有更紧凑结构的原生态移动，因此，由于景观粗糙度增加，扩散系数较小。拟合的数据与伊辛样模型产生一个相对较小的位置依赖的扩散系数。这一发现与实验和计算的折叠速率之间的良好相关性是一致的，该相关性基于对每种蛋白质使用相同的扩散系数的自由能垒高度。
Nanosecond laser T-jump was used to measure the viscosity dependence of the folding kinetics of the villin subdomain under conditions where the viscogen has no effect on its equilibrium properties. The dependence of the unfolding/refolding relaxation time on solvent viscosity indicates a major contribution to the dynamics from internal friction. The internal friction increases with increasing temperature, suggesting a shift in the transition state along the reaction coordinate toward the native state with more compact structures, and therefore, a smaller diffusion coefficient due to increased landscape roughness. Fitting the data with an Ising-like model yields a relatively small position dependence for the diffusion coefficient. This finding is consistent with the excellent correlation found between experimental and calculated folding rates based on free energy barrier heights using the same diffusion coefficient for every protein.