Lu D R, Lee S J, Park K
Purdue University, School of Pharmacy, West Lafayette, IN 47907.
J Biomater Sci Polym Ed. 1991;3(2):127-47. doi: 10.1163/156856291x00232.
Of the interactions that govern protein adsorption on polymer surfaces, solvation interactions (repulsive hydration and attractive hydrophobic interactions) are thought to be among the most important. The solvation interactions in protein adsorption, however, have not been dealt with in theoretical calculation of the adsorption energy owing to the difficulties in modelling such interactions. We have evaluated the solvation interaction energies using the fragment constant method of calculating the partition coefficients of amino acids. The fundamental assumption of this approach is that the partition coefficients of amino acids between water and organic solvent phases are related to the free energies of transfer from bulk water to the polymer surface. The X-ray crystallographic protein structures of lysozyme, trypsin, immunoglobulin Fab, and hemoglobin from the Brookhaven Protein Data Bank were used. The model polymer surfaces were polystyrene, polypropylene, polyethylene, poly(hydroxyethyl methacrylate) [poly(HEMA)], and poly(vinyl alcohol). All possible adsorption orientations of the proteins were simulated to study the effect of protein orientation on the solvation interactions. Protein adsorption on either hydrophobic or hydrophilic polymer surfaces was examined by considering the sum of solvation and other interaction energies. The results showed that the contribution of the solvation interaction to the total protein adsorption energy was significant. The average solvation interaction energy ranged from -259.1 to -74.1 kJ/mol for the four proteins on the hydrophobic polymer surfaces, such as polystyrene, polypropylene, and polyethylene. On the other hand, the average solvation interaction energies on hydrophilic surfaces such as poly(HEMA) and poly(vinyl alcohol) were larger than zero. This indicates that repulsive hydration interactions are in effect for protein adsorption on hydrophilic polymer surfaces. The total interaction energies of the proteins with hydrophobic surfaces were always lower than those with more hydrophilic surfaces. This trend is in agreement with the experimental observations in the literature. This study suggests that consideration of the solvation interaction energies is necessary for accurate calculation of the protein adsorption energies.
在决定蛋白质在聚合物表面吸附的相互作用中，溶剂化相互作用（排斥性水合作用和吸引性疏水相互作用）被认为是最重要的相互作用之一。然而，由于对这类相互作用进行建模存在困难，蛋白质吸附中的溶剂化相互作用在吸附能的理论计算中尚未得到处理。我们使用计算氨基酸分配系数的片段常数法评估了溶剂化相互作用能。该方法的基本假设是氨基酸在水相和有机溶剂相之间的分配系数与从本体水转移到聚合物表面的自由能相关。使用了布鲁克海文蛋白质数据库中溶菌酶、胰蛋白酶、免疫球蛋白Fab和血红蛋白的X射线晶体学蛋白质结构。模型聚合物表面为聚苯乙烯、聚丙烯、聚乙烯、聚（甲基丙烯酸羟乙酯）[聚（HEMA）]和聚乙烯醇。模拟了蛋白质所有可能的吸附取向，以研究蛋白质取向对溶剂化相互作用的影响。通过考虑溶剂化和其他相互作用能的总和，研究了蛋白质在疏水或亲水聚合物表面的吸附情况。结果表明，溶剂化相互作用对总蛋白质吸附能的贡献显著。对于聚苯乙烯、聚丙烯和聚乙烯等疏水聚合物表面上的四种蛋白质，平均溶剂化相互作用能范围为-259.1至-74.1 kJ/mol。另一方面，聚（HEMA）和聚乙烯醇等亲水表面上的平均溶剂化相互作用能大于零。这表明排斥性水合作用对蛋白质在亲水聚合物表面的吸附起作用。蛋白质与疏水表面的总相互作用能总是低于与亲水性更强表面的总相互作用能。这一趋势与文献中的实验观察结果一致。本研究表明，准确计算蛋白质吸附能需要考虑溶剂化相互作用能。
