Numerous studies have suggested a significant role that protein dynamics play in optimizing enzyme catalysis, and changes in conformational sampling offer a window to explore this role. Thermolysin from Bacillus thermoproteolyticus rokko, which is a heat-stable zinc metalloproteinase, serves here as a model system to study changes of protein function and conformational sampling across a temperature range of 16-36 °C. The temperature dependence of kinetics of thermolysin showed a biphasic transition at 26 °C that points to potential conformational and dynamic differences across this temperature. The non-Arrhenius behavior observed resembled results from previous studies of a thermophilic alcohol dehydrogenase enzyme, which also indicated a biphasic transition at ambient temperatures. To explore the non-Arrhenius behavior of thermolysin, room temperature crystallography was applied to characterize structural changes in a temperature range across the biphasic transition temperature. The alternate conformation of side chain fitting to electron density of a group of residues showed a higher variability in the temperature range from 26 to 29 °C, which indicated a change in conformational sampling that correlated with the non-Arrhenius break point.

中文翻译：

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构象采样和动力学变化跨越热裂解酶中非阿累尼乌斯的断裂点。

大量研究表明，蛋白质动力学在优化酶催化过程中起着重要作用，构象采样的变化为探索这种作用提供了一个窗口。来自热稳定芽孢杆菌的热溶菌素是热稳定的锌金属蛋白酶，在这里用作模型系统，以研究蛋白质功能和构象采样在16-36°C的温度范围内的变化。嗜热菌蛋白酶动力学的温度依赖性在26°C时显示出双相转变，表明在该温度下可能存在构象和动态差异。观察到的非阿伦尼乌斯行为类似于先前对嗜热醇脱氢酶的研究结果，该研究还表明在环境温度下为双相转变。要探索嗜热菌素的非阿累尼乌斯行为，应用室温晶体学来表征跨双相转变温度的温度范围内的结构变化。侧链拟合对一组残基的电子密度的交替构象在26至29°C的温度范围内显示出较高的变异性，这表明构象采样的变化与非阿伦尼休斯断裂点相关。