分子动力学模拟探索乳克鲁维酵母来源的β-半乳糖苷酶热变性条件

为了研究乳克鲁维酵母中β-半乳糖苷酶可能的熔解温度，采用分子动力学模拟的方法，分别对4种不同温度条件下(35、50、65、80 ℃)的β-半乳糖苷酶进行了50 ns的计算模拟，分析了酶的构象变化以及酶活性中心的差异。研究在原子水平揭示了β-半乳糖苷酶的温度耐受等关键信息:35 ℃为最适酶活温度，该温度下的β-半乳糖苷酶的整体构象最稳定；该酶在50 ℃时的原子波动性显著增加，表明此温度可能趋近熔解温度临界值；蛋白在大于65 ℃条件下丧失柔性，说明蛋白已经变性；进一步的构象分析发现80 ℃高温会破坏β-D-半乳吡喃糖(GAL)结合位点微环境。

The Thermal Denaturation Conditions of β-galactosidase in Kluyveromyces lactis under Molecular Dynamics Simulation

To study the possible melting temperature of β-galactosidase in Kluyveromyces lactis, molecular dynamics (MD) simulations at four different temperatures (35, 50, 65 and 80 ℃) were performed for 50 ns, respectively. Then the conformational change of the enzyme and the difference of the enzyme active center were analyzed. The crucial information of temperature tolerance of β-galactosidase at the atomic level was revealed as follows: the overall conformation of β-galactosidase was the most stable at 35 ℃, which was the optimal temperature for enzyme activity; the atomic fluctuation of the enzyme increased significantly at 50 ℃, indicating that this temperature may approach the critical value of melting temperature; when the temperature was higher than 65 ℃, the structure of the protein lost its flexibility, which indicated that the protein had reached the melting temperature. Further conformational analysis showed that the microenvironment of β-D-galactopyranose (GAL) binding sites was destroyed at 80 ℃.