天然的低温脂肪酶往往结构热稳定性比较差，制约了其长时间有效地发挥催化作用及保存。该研究以来源于白色念珠菌（ Candida albicans ）的低温脂肪酶Lipase 5为对象，运用相关分子动力学方法进行研究，提出了提高其热稳定性的理论策略。首先运用同源建模方法构建目标蛋白的三维结构模型；然后通过18 ns分子动力学模拟，锚定目标蛋白不稳定区域中柔性氨基酸（甘氨酸）的位置，并将这些柔性氨基酸位点突变为刚性氨基酸（脯氨酸）；最后利用分子动力学模拟来验证这些突变对蛋白质热稳定性的影响。结果发现，将Lipase 5三维结构中的第279位甘氨酸突变为脯氨酸后，使得蛋白质热稳定性增强。这为类似低温脂肪酶的热稳定性改造的实验设计提供了理论支持。%The thermostability of naturally cold -adapted lipases is often relatively poor , limiting their long cata-lytic effect and long-term preservation.In the current study , one cold-adapted lipase Lipase 5 from Candida albicans was investigated by means of molecular dynamics method in order to improve its thermal stability.First the three-dimensional model of Lipase 5 was constructed by homology modeling.Then 18 ns molecular dynam-ics simulations were utilized to find the unstable region in Lipase 5 out of the protein active center with high con-formational fluctuations , and one possible mutant site 279-Gly was detected.It is finally proved that mutation of flexible 279-Gly to rigid Proline endows Lipase 5 enhances thermostability.Our studies may provide theoretical direction and support to design experiments of reforming thermal stability of cold active lipases.
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