马铃薯贮藏蛋白Patatin及其突变体分子动力学和分子对接的研究

Molecular Dynamics and Docking Studies on Potato Storage Protein Patatin and Tts Several Mutants

马铃薯贮藏蛋白Patatin具有水解脂肪的能力,且特定位点的突变能够影响Patatin的水解酶活性.Patatin的水解酶活性中心是由Ser77和Asp215组成,首先采用分子动力学方法研究Patatin及其突变体的稳定性和构象变化,通过结构比对没有发现构象规律性的变化,然后采用分子对接方法,发现了两个基团(Patatin及其突变体活性位点Ser77的羟基与底物p-硝基苯基癸酯的酯键)间的距离具有规律性:即H109A和D182A(活性减弱)两个基团之间的距离偏大,而R368A,E140A,H109N(活性增强)两个基团之间的距离偏小,符合之前的生化数据.这说明Ser77的羟基与底物PNPC10的酯键间的距离可能能够影响底物小分子与Patatin蛋白的结合,从而影响Patatin酯酶的活性.同时,根据细胞内溶质磷脂酶A2(cPLA2)反应过程,我们推测了Patatin与底物之间可能的催化机制.

Patatin from potato has the capacity of hydrolasing lipid with the catalytic dyad consisting of SerT？ and Asp215. According to an early study, certain mutations will affect the activity of hydrolase. In this study, we have performed molecular dynamics simulation （MD） to investigate the stabilities and conformational changes of Patatin mutations. MD results revealed that WT did not show distinct difference to its mutants in stability. The docking results revealed that the distance between the hydroxyl in Ser and the carbon of the ester bond （PNPC10） corresponded well with its activity. With the increase of the distance of the hydroxyl in Ser77 and the carbon of the ester bond, the activity of patatin decreased, vice versa. These results revealed that the distance between the hydroxyl of Ser77 and the carbon of the ester bond has an important role in its enzymatic activity. In addition, the catalytic mechanism of patatin was predicted according to the mechanism of cPLA2 .