Improving enzyme stability is very important for enzyme applications. Structural modification is a reliable and effective method to improve the characteristics of protein. By artificially extending the C-terminus, 6 domain modification variants of different sizes were constructed, and a new enzyme species with high stability was obtained. Experimental results affirmed that high stability can be achieved by decreasing the degree of domain freedom. The optimum temperatures of domain modification variants were improved by 10 °C compared with the original enzyme. Specifically, compared with the original enzyme, the half-life of the variant dexYG-fdx (D-F) was increased to 280% under 35 °C and 200% under 45 °C, and the pH tolerance range was wider. Further structural simulations and molecular docking studies provided a reasonable explanation (The increased domain reduced the degree of freedom of the enzyme terminal to some extent) for this variant to increase stability and produce dextran. This study can provide valuable information for increasing the characteristics of recombinant dextransucrase.

提高酶稳定性对于酶应用非常重要。结构修饰是改善蛋白质特性的一种可靠有效的方法。通过人工延伸C端，构建了6个不同大小的结构域修饰变体，获得了高稳定性的新酶种。实验结果证实，通过降低域自由度可以实现高稳定性。与原始酶相比，结构域修饰变体的最适温度提高了 10 °C。具体来说，与原酶相比，变体dexYG-fdx（DF）的半衰期在35℃下提高到280%，在45℃下提高到200%，pH耐受范围更广。进一步的结构模拟和分子对接研究为该变体增加稳定性和产生葡聚糖提供了合理的解释（增加的域在一定程度上降低了酶末端的自由度）。本研究可为提高重组葡聚糖蔗糖酶的特性提供有价值的信息。