Koutsopoulos Sotirios, van der Oost John, Norde Willem
Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Wageningen, The Netherlands.
Proteins. 2005 Nov 1;61(2):377-84. doi: 10.1002/prot.20606.
The dynamic behavior of an endoglucanase from the hyperthermophilic microorganism Pyrococcus furiosus was investigated using elastic neutron scattering. The temperature dependence of the atomic motions was correlated with conformational and functional characteristics of the enzyme. The onset of biological function at temperatures higher than approximately 25 degrees C (the hyperthermostable enzyme is essentially inactive at room temperature) was associated with a dynamical transition in the anharmonic motions domain. This transition from the nonactive to the enzymatically active conformation involved structurally similar conformational substates in the energy landscape. From the mean-square displacement of the protein atoms, the molecular flexibility and the effective force constants were calculated at different temperature zones. The results showed that the activity increases at higher temperatures where the intramolecular bonds are weakened and the overall rigidity of the protein is decreased. Further temperature increase resulted in significantly increased atomic fluctuations featuring heat denaturation of the protein.
利用弹性中子散射研究了嗜热微生物激烈热球菌来源的一种内切葡聚糖酶的动力学行为。原子运动的温度依赖性与该酶的构象和功能特性相关。在高于约25摄氏度的温度下生物功能的起始（这种超嗜热酶在室温下基本无活性）与非谐运动域中的动力学转变有关。从无活性构象到酶促活性构象的这种转变涉及能量景观中结构相似的构象亚态。根据蛋白质原子的均方位移，计算了不同温度区域的分子柔韧性和有效力常数。结果表明，在较高温度下活性增加，此时分子内键减弱，蛋白质的整体刚性降低。进一步升高温度导致原子波动显著增加，其特征是蛋白质发生热变性。
