Molecular dynamics simulations were performed to understand the adsorption of positive-charged lysozyme onto negative-charged polyvinylidene fluoride membrane at three pH and two ionic strengths. The lysozyme was initialized at six orientations at 10 Å from the membrane and adsorption was deemed to occur when the lysozyme is less than 4 Å from the membrane. Local interactions are clearly important: (i) despite opposite net charges, no adsorption occurs in some cases throughout; (ii) lysozyme-membrane separation distances differ among the initial orientations of lysozyme; and (iii) the correlation between lysozyme-membrane interaction energy and adsorption probability is poor. Correspondingly, seven key local adsorption sites on lysozyme were identified. Of the two most common sites, one anchors due to electrostatics, while the other is not electrostatics-based. Also, different sites are dominant in different feed conditions and have different interaction energies. These results reveal the importance of local interactions in membrane fouling by proteins in different feed conditions.

中文翻译：

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溶菌酶对膜的污染：局部相互作用的影响

进行分子动力学模拟以了解带正电荷的溶菌酶在三种 pH 值和两种离子强度下吸附到带负电荷的聚偏二氟乙烯膜上。溶菌酶在距膜 10 埃处的六个方向上初始化，当溶菌酶距膜小于 4 埃时，认为发生吸附。局部相互作用显然很重要：（i）尽管净电荷相反，但在某些情况下始终没有发生吸附；(ii) 溶菌酶-膜分离距离因溶菌酶的初始方向而异；(iii) 溶菌酶-膜相互作用能与吸附概率之间的相关性较差。相应地，鉴定了溶菌酶上的七个关键局部吸附位点。在两个最常见的位置中，一个由于静电而锚定，而另一个不是基于静电的。此外，不同的位点在不同的进料条件下占主导地位，并具有不同的相互作用能。这些结果揭示了不同进料条件下蛋白质在膜污染中局部相互作用的重要性。