基于酶热稳定性系统计算的乳酸氧化酶热稳定性改造

Improving the Thermal Stability of Lactate Oxidase by ETSS

乳酸氧化酶能够催化乳酸氧化为丙酮酸,具有重要的工业应用价值,但已有研究表明,不同来源的乳酸氧化酶均存在热稳定性不好的问题,影响了其在工业当中的应用。目前对于乳酸氧化酶的研究报道较少,对其热稳定性的改造更未见报道,因此提高乳酸氧化酶的热稳定性具有重要意义。克隆表达了一个高比活乳酸氧化酶(Eg LOD),通过生物信息学辅助分析及表面电荷分析软件(ETSS)对乳酸氧化酶的蛋白结构进行理性分析,基于蛋白表面电荷分布优化设计了9个突变体尝试对其进行热稳定性改良。通过对突变体的筛选获得了两个有效提升热稳定性的突变体D250N,D281N,在60℃下处理30 min仍然能够保持50%以上的酶活,而野生型Eg LOD酶活仅剩20%左右。

Lactate oxidase can catalyze the oxidation of lactic acid to pyruvate, thus it has important industrial application value. However, lactate oxidases from different sources share the common problem of poor thermal stability, which impacts its application in industry. The researches on laclate oxidase are less reported, and there was no report on the improvement of its thermal stability, therefore improving the thermal stability of lactate oxidase is of great significance. In this study, we cloned and expressed highly specific lactate oxidase EgLOD, and used biointormatics and surface charge analysis software ETSS to analyze the protein structure of lactate oxidase. We designed 9 mutants for the experiment of improving their thermal stability based on the distribution and optimization of protein surface char, 2 mutants D250N and D281N presented efficient enhanced thermal stability after screening. After incubated under 60℃ for 30 rain, they remained more than 50% of the enzyme activity, while the wild type EgLOD remained only 20%.