蛋白质在材料表面吸附的分子动力学模拟
发布时间：2018-09-02 08:40
【摘要】：蛋白质与材料间相互作用并会自发吸附到材料表面是自然界中广泛存在的一种现象。在许多情况下,蛋白质吸附是有利的,但在更多时候,蛋白质吸附到材料表面会带来不希望的结果。特别是在海洋环境中发生的生物污损,因海洋生物附着引起的污损会加速在海中作业的金属设备腐蚀,影响设施的正常使用,增加船舶的航行阻力并会使海中仪表或转动机失灵等。而海洋生物污染的初期主要是海洋生物分泌的蛋白质粘液在表面的吸附,因此研究蛋白质与材料间相互作用过程中蛋白质的构型变化、作用机理及不同材料对吸附的影响等,有助于我们理解材料吸附蛋白质作用机理,以求找到具有更好防污效果的防污材料。本论文主要运用分子动力学模拟方法研究了蛋白质与不同固体材料表面间的相互作用。分子动力学模拟可以大大降低实验的盲目性和重复实验的耗材与耗时性,同时还可以直观地从分子水平上观察到体系中蛋白质三维结构的变化,加深对蛋白质在不同材料表面吸附机理的认识,以求找到更好的防污材料。具体研究内容包括以下几个方面：(1)采用分子动力学模拟方法研究了溶菌酶蛋白在两种典型聚合物防污材料聚乙二醇(PEG)和聚二甲基硅氧烷(PDMS)表面的吸附行为,在微观上探讨了聚合物膜表面性质对溶菌酶蛋白吸附的影响。对蛋白质在聚合物膜表面的吸附现象,能量变化和表面水化层分子的动力学行为进行分析,发现：相比PEG膜,蛋白质与PDMS膜表面的结合能量较高,使其结合更加紧密稳定；蛋白质要吸附到材料表面需克服表面水化层分子引起的能障,PEG表面与水分子之间结合紧密,造成蛋白质在其表面吸附需要克服更高的能量,不利于蛋白质的吸附,合理地解释了PEG防污膜相对于PDMS膜具有更佳防污效果的原因。(2)运用分子动力学手段分析了蛋白质与不同末端官能团终止的自组装单分子层膜(SAMs)间的相互作用。SAMs表面结构和化学性质可以通过改变表面组成和末端官能团来调节,能在分子尺度上进行很好的表征,是研究蛋白质界面行为的理想平台。通过分析溶菌酶蛋白与疏水性的CH3-SAM及两种亲水性的CH2OH-SAM和COOH-SAM间的相互作用,对比蛋白质在膜表面的参数变化和膜表面水分子的动力学行为,得到结论：溶菌酶蛋白与疏水性的CH3-SAMs膜间的相互作用能最大,在其上发生的形变较大,利于蛋白质吸附并在吸附后难以自行脱附；亲水性SAMs膜表面与水化层分子的结合更加紧密,蛋白质要吸附到膜表面需要克服更高的能量,吸附更加困难,对比COOH-SAMs, CH2OH-SAMs阻抗蛋白质吸附的能力较强,防污效果最好。(3)采用分子动力学模拟方法研究疏水蛋白在二氧化硅表面的动力学行为。疏水蛋白是目前已知的具有最强表面活性的蛋白质,其在材料表面能够降低材料表面水的表面张力,率先吸附到材料表面形成一层真菌保护膜并产生孢子,对于海洋生物污染初期形成的生物条件膜有重要贡献作用。为揭示海洋环境中岩石表面蛋白质吸附现象机理,我们研究了疏水蛋白从4个不同方向(每个方向旋转90°)放置在二氧化硅表面的吸附状况及蛋白质的构型变化,结果表明：蛋白质不同方向的放置会影响其与基底间的相互作用,甚至发生不吸附的现象,并且蛋白质在整个动力学过程中的翻转变化和最终吸附构型是不同的,统计吸附的氨基酸类型,发现疏水性氨基酸所占比例较大；分析4个体系的蛋白质构型参数变化,回转半径和均方根偏差相差不大,蛋白质不同方向的放置对构型变化的影响不大,且在模拟时间内没有发生变性行为；对比4个体系的能量变化,发现能量大小与蛋白质吸附在表面的氨基酸类型有关,且吸附越紧密的体系能量越高。
[Abstract]:It is a widespread phenomenon in nature that proteins interact with materials and spontaneously adsorb onto their surfaces. In many cases, protein adsorption is beneficial, but in more cases, protein adsorption on the surface of materials can lead to undesirable results. Especially in marine environments, biofouling occurs because of marine organisms. The fouling caused by attachment will accelerate the corrosion of metal equipment in marine operation, affect the normal use of facilities, increase the navigation resistance of ships and cause the failure of instruments or rotating machines in the sea. The structural changes of proteins, the mechanism of action and the effect of different materials on adsorption are helpful for us to understand the mechanism of protein adsorption and find better antifouling materials. Interaction. Molecular dynamics simulation can greatly reduce the blindness of the experiment and the consumptivity and time-consuming of repeated experiments. At the same time, the changes of three-dimensional structure of proteins in the system can be observed intuitively at the molecular level. The understanding of the adsorption mechanism of proteins on different materials can be deepened to find better antifouling materials. The research contents include the following aspects: (1) The adsorption behavior of lysozyme on the surface of two typical polymer antifouling materials, polyethylene glycol (PEG) and polydimethylsiloxane (PDMS), was studied by molecular dynamics simulation. The effect of the surface properties of polymer membrane on the adsorption of lysozyme was discussed microscopically. Adsorption phenomena, energy changes and kinetic behavior of surface hydration layer molecules were analyzed. It was found that the binding energy between protein and PDMS membrane was higher than that of PEG membrane, and the binding energy between protein and PDMS membrane was tighter and more stable. The tight binding between the molecules makes it necessary to overcome higher energy for protein adsorption on its surface, which is not conducive to protein adsorption. The reason why PEG antifouling membrane has better antifouling effect than PDMS membrane is reasonably explained. (2) The self-assembled monolayer membrane (SA) terminated by different end functional groups was analyzed by molecular dynamics. The surface structure and chemical properties of SAMs can be well characterized at the molecular scale by changing the surface composition and terminal functional groups. It is an ideal platform for studying the interfacial behavior of proteins. The interaction between Lysozyme protein and hydrophobic CH3-SAMs membrane was studied. The results showed that the interaction energy between Lysozyme protein and hydrophobic CH3-SAMs membrane was the greatest, and the deformation on it was larger, which was beneficial to protein adsorption and difficult to desorb after adsorption. Compared with COOH-SAMs, CH2OH-SAMs have stronger ability of impedance protein adsorption and the best antifouling effect. (3) The kinetic behavior of hydrophobic protein on the surface of silica was studied by molecular dynamics simulation. Proteins with the strongest surface activity are known to reduce the surface tension of water on the surface of materials. They take the lead in adsorbing to the surface of materials to form a protective film of fungi and produce spores. The adsorption of hydrophobic proteins on silica surface from four different directions (rotating 90 degrees in each direction) and the structural changes of the proteins were studied. The results showed that the different orientations of the proteins would affect the interaction between the proteins and the substrate, and even lead to non-adsorption. The inversion and final adsorption configurations were different in the whole kinetic process, and the hydrophobic amino acids accounted for a large proportion according to the type of adsorption amino acids. Compared with the energy changes of the four systems, it was found that the energy was related to the type of amino acids adsorbed on the surface of the protein, and the energy of the system with the tighter adsorption was higher.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O647.31;X55
本文编号：2218836
[Abstract]:It is a widespread phenomenon in nature that proteins interact with materials and spontaneously adsorb onto their surfaces. In many cases, protein adsorption is beneficial, but in more cases, protein adsorption on the surface of materials can lead to undesirable results. Especially in marine environments, biofouling occurs because of marine organisms. The fouling caused by attachment will accelerate the corrosion of metal equipment in marine operation, affect the normal use of facilities, increase the navigation resistance of ships and cause the failure of instruments or rotating machines in the sea. The structural changes of proteins, the mechanism of action and the effect of different materials on adsorption are helpful for us to understand the mechanism of protein adsorption and find better antifouling materials. Interaction. Molecular dynamics simulation can greatly reduce the blindness of the experiment and the consumptivity and time-consuming of repeated experiments. At the same time, the changes of three-dimensional structure of proteins in the system can be observed intuitively at the molecular level. The understanding of the adsorption mechanism of proteins on different materials can be deepened to find better antifouling materials. The research contents include the following aspects: (1) The adsorption behavior of lysozyme on the surface of two typical polymer antifouling materials, polyethylene glycol (PEG) and polydimethylsiloxane (PDMS), was studied by molecular dynamics simulation. The effect of the surface properties of polymer membrane on the adsorption of lysozyme was discussed microscopically. Adsorption phenomena, energy changes and kinetic behavior of surface hydration layer molecules were analyzed. It was found that the binding energy between protein and PDMS membrane was higher than that of PEG membrane, and the binding energy between protein and PDMS membrane was tighter and more stable. The tight binding between the molecules makes it necessary to overcome higher energy for protein adsorption on its surface, which is not conducive to protein adsorption. The reason why PEG antifouling membrane has better antifouling effect than PDMS membrane is reasonably explained. (2) The self-assembled monolayer membrane (SA) terminated by different end functional groups was analyzed by molecular dynamics. The surface structure and chemical properties of SAMs can be well characterized at the molecular scale by changing the surface composition and terminal functional groups. It is an ideal platform for studying the interfacial behavior of proteins. The interaction between Lysozyme protein and hydrophobic CH3-SAMs membrane was studied. The results showed that the interaction energy between Lysozyme protein and hydrophobic CH3-SAMs membrane was the greatest, and the deformation on it was larger, which was beneficial to protein adsorption and difficult to desorb after adsorption. Compared with COOH-SAMs, CH2OH-SAMs have stronger ability of impedance protein adsorption and the best antifouling effect. (3) The kinetic behavior of hydrophobic protein on the surface of silica was studied by molecular dynamics simulation. Proteins with the strongest surface activity are known to reduce the surface tension of water on the surface of materials. They take the lead in adsorbing to the surface of materials to form a protective film of fungi and produce spores. The adsorption of hydrophobic proteins on silica surface from four different directions (rotating 90 degrees in each direction) and the structural changes of the proteins were studied. The results showed that the different orientations of the proteins would affect the interaction between the proteins and the substrate, and even lead to non-adsorption. The inversion and final adsorption configurations were different in the whole kinetic process, and the hydrophobic amino acids accounted for a large proportion according to the type of adsorption amino acids. Compared with the energy changes of the four systems, it was found that the energy was related to the type of amino acids adsorbed on the surface of the protein, and the energy of the system with the tighter adsorption was higher.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O647.31;X55
【参考文献】
相关期刊论文 前1条
1 赵晓燕;海洋天然产物防污研究进展[J];材料开发与应用;2001年04期
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