分子动力学探究高压对β-乳球蛋白与多酚结合的影响

The effect of high pressure on the combination of β-lactoglobulin and polyphenols using molecular dynamic model

为探究不同压力下多酚与蛋白的结合规律,以表没食子儿茶素没食子酸酯(epigallocatechin gallate, EGCG)和β-乳球蛋白为研究对象,采用分子对接和分子模拟研究两者结合能和结合机制在0.1、200、500、800 MPa时的变化。结果表明,EGCG常压下主要结合在疏水腔(1号区域),蛋白经200和500 MPa处理后,EGCG主要结合在蛋白表面的2号区域,而800 MPa处理后至少有5个结合区域。以1号结合位点为对象进行150 ns的分子动力学模拟过程,发现200 MPa的压力处理能使蛋白结构更稳定,而500和800 MPa压力下蛋白稳定性略为降低。500 MPa及以上的压力能使蛋白的疏水表面积、α-螺旋和β-折叠减少。EGCG与β-乳球蛋白的结合自由能随压力的增加而降低,其中主要是由范德华力、氢键作用减弱所致。另外,高压下蛋白结构的变化,特别是结合位点处的变化也显著影响了EGCG与蛋白的结合。

To investigate the effects of high pressure on the combination of protein and polyphenols, the binding energy and binding mechanism between epigallocatechin gallate(EGCG) and β-lactoglobulin under the pressure of 0.1, 200, 500, and 800 MPa was studied using molecular docking and molecular dynamics model. The results showed that EGCG located mainly in the internal cavity of the β-barrel under 0.1 MPa(site Ⅰ), and the main binding site was in the surface of protein(site Ⅱ) after treatment of 200 or 500 MPa. However, there were at least five binding sites when protein was treated by 800 MPa. 150 ns molecular dynamics simulation was carried out for binding site Ⅰ. It was found that the protein structure was more stable under the pressure of 200 MPa, while its stability was slightly decreased under the pressure of 500 and 800 MPa. The hydrophobic surface area, α-helix, and β-sheet of the protein were decreased under the pressure of 500 or 800 MPa. The binding free energy of EGCG with β-lactoglobulin decreased with the increase of pressure, which mainly due to the weakening of van der Waals force and hydrogen bond. In addition, the change of protein structure under high pressure, especially in binding site, also significantly affected the binding of EGCG to protein.