Rocking motion in solid proteins as studied by solid-state NMR techniques

该项目的目的是比较研究固体蛋白质样品中特定类型的分子动力学，总体上限制蛋白质运动作为一个整体，即摇摆运动。这种类型的蛋白质迁移是最近才发现的，其性质仍不完全清楚。摆动运动的参数，即振幅，相关时间，相关时间分布的宽度和活化能，将通过15N和13C弛豫（T1rho）和交换（偶极和CSA CODEX）固态核磁共振技术实验确定，涵盖微秒到毫秒范围的分子运动。实验将对两种分子量非常不同的蛋白质GB1和嗜热蛋白酶体进行。这两种蛋白质将在不同水合水平下以微晶体和无定形粉末的形式进行研究。嗜热蛋白酶体也将以一种沉积形式在魔角旋转转子中进行研究。最终，我们希望找到以下问题的答案：a)不同大小和结构特征的蛋白质之间的摇摆运动有何不同？b)相同蛋白质在结晶和无定形状态下的摇摆运动与在mas沉积物中的摇摆运动有什么不同？c)蛋白质之间的水合层如何影响摇摆运动的参数？d)摇摆运动的相关时间分布有多宽？

The aim of the project is a comparative study of a specific type of molecular dynamics in solid protein samples, overall restricted protein motion as a whole, that is rocking motion. This type of protein mobility was discovered only recently and its nature is still not fully clear. The parameters of the rocking motion, that is the amplitude, the correlation time, the width of the correlation time distribution and the activation energy, will be experimentally determined using the 15N and 13C relaxation (T1rho) and exchange (dipolar and CSA CODEX) solid-state NMR techniques that cover microsecond to millisecond ranges of molecular motions. The experiments will be conducted on two proteins, GB1 and thermophilic proteasome, having very different molecular weight. Both proteins will be studied in a form of microcrystals and amorphous powders at different hydration levels. Thermophilic proteasome will also be investigated in a form of sediment in a magic-angle-spinning rotor. Ultimately, we hope to find answers on the following questions: a) How different is the rocking motion between proteins of different size and structural features? b) What is the difference between the rocking motion of the same protein in crystalline and amorphous states and in MAS-sediments? c) How the hydration layer between proteins affects the parameters of the rocking motion? d) How wide is the correlation times distribution of the rocking motion?