Department of NMR-based Structural Biology, Max-Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany.
Protein Sci. 2012 Apr;21(4):562-70. doi: 10.1002/pro.2045. Epub 2012 Mar 2.
Physiological processes such as protein folding and molecular recognition are intricately linked to their dynamic signature, which is reflected in their thermal coefficient. In addition, the local conformational entropy is directly related to the degrees of freedom, which each residue possesses within its conformational space. Therefore, the temperature dependence of the local conformational entropy may provide insight into understanding how local dynamics may affect the stability of proteins. Here, we analyze the temperature dependence of internal methyl group dynamics derived from the cross-correlated relaxation between dipolar couplings of two CH bonds within ubiquitin. Spanning a temperature range from 275 to 308 K, internal methyl group dynamics tend to increase with increasing temperature, which translates to a general increase in local conformational entropy. With this data measured over multiple temperatures, the thermal coefficient of the methyl group order parameter, the characteristic thermal coefficient, and the local heat capacity were obtained. By analyzing the distribution of methyl group thermal coefficients within ubiquitin, we found that the N-terminal region has relatively high thermostability. These results indicate that methyl groups contribute quite appreciably to the total heat capacity of ubiquitin through the regulation of local conformational entropy.
生理过程，如蛋白质折叠和分子识别，与其动态特征密切相关，这反映在它们的热系数中。此外，局部构象熵与自由度直接相关，每个残基在其构象空间中都具有自由度。因此，局部构象熵的温度依赖性可以提供深入了解局部动力学如何影响蛋白质稳定性的见解。在这里，我们分析了来自泛素中两个 CH 键偶极耦合之间交叉相关弛豫的内部甲基基团动力学的温度依赖性。温度范围从 275 到 308 K，内部甲基基团动力学随温度升高而增加，这意味着局部构象熵普遍增加。通过在多个温度下测量这些数据，我们获得了甲基组序参数的热系数、特征热系数和局部热容。通过分析泛素中甲基热系数的分布，我们发现 N 末端区域具有相对较高的热稳定性。这些结果表明，甲基基团通过调节局部构象熵，对泛素的总热容有相当大的贡献。
