Grimaldo Marco, Roosen-Runge Felix, Hennig Marcus, Zanini Fabio, Zhang Fajun, Jalarvo Niina, Zamponi Michaela, Schreiber Frank, Seydel Tilo
Institut Max von Laue - Paul Langevin (ILL), CS 20156, F-38042 Grenoble, France.
Phys Chem Chem Phys. 2015 Feb 14;17(6):4645-55. doi: 10.1039/c4cp04944f.
The dynamics of proteins in solution is a complex and hierarchical process, affected by the aqueous environment as well as temperature. We present a comprehensive study on nanosecond time and nanometer length scales below, at, and above the denaturation temperature Td. Our experimental data evidence dynamical processes in protein solutions on three distinct time scales. We suggest a consistent physical picture of hierarchical protein dynamics: (i) self-diffusion of the entire protein molecule is confirmed to agree with colloid theory for all temperatures where the protein is in its native conformational state. At higher temperatures T > Td, the self-diffusion is strongly obstructed by cross-linking or entanglement. (ii) The amplitude of backbone fluctuations grows with increasing T, and a transition in its dynamics is observed above Td. (iii) The number of mobile side-chains increases sharply at Td while their average dynamics exhibits only little variations. The combination of quasi-elastic neutron scattering and the presented analytical framework provides a detailed microscopic picture of the protein molecular dynamics in solution, thereby reflecting the changes of macroscopic properties such as cluster formation and gelation.
溶液中蛋白质的动力学是一个复杂的、具有层次结构的过程，受水环境以及温度的影响。我们在低于、等于和高于变性温度Td的纳秒时间尺度和纳米长度尺度上进行了一项全面研究。我们的实验数据证明了蛋白质溶液中在三个不同时间尺度上的动力学过程。我们提出了一个关于蛋白质层次动力学的一致物理图景：(i) 对于蛋白质处于其天然构象状态的所有温度，整个蛋白质分子的自扩散被证实与胶体理论相符。在较高温度T>Td时，自扩散会因交联或缠结而受到强烈阻碍。(ii) 主链波动的幅度随温度升高而增大，并且在Td以上观察到其动力学发生转变。(iii) 可移动侧链的数量在Td时急剧增加，而它们的平均动力学仅表现出很小的变化。准弹性中子散射与所提出的分析框架相结合，提供了溶液中蛋白质分子动力学的详细微观图景，从而反映了诸如聚集体形成和凝胶化等宏观性质的变化。
