Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, and Center for Complex Molecular Systems and Biomolecules, Flemingovo nam. 2, 16610 Prague 6, Czech Republic.
J Phys Chem A. 2009 Mar 12;113(10):1969-75. doi: 10.1021/jp807993f.
Ion specific behavior of halides at surfaces of aqueous basic amino acids is unraveled by means of molecular dynamics simulations employing both nonpolarizable and polarizable force fields. Analysis in terms of density plots, cumulative sums, and residence times provides a clear, robust, and quantitative picture of specific ion effects. Small anions like fluoride, but not heavier halides, exhibits strong affinity for positively charged groups in the order guanidinium > imidazolium > ammonium. In contrast, large soft anions such as iodide are weakly attracted to nonpolar regions of the amino acids. Because interactions of halides with positively charged groups exhibit a local character and are not overwhelmingly strong, similar behavior will be observed (in an additive sense) as well at surfaces of hydrated proteins.
通过使用非极化和极化力场的分子动力学模拟，揭示了卤化物在水合碱性氨基酸表面的离子特异性行为。通过密度图、累积和停留时间的分析，提供了一个清晰、稳健和定量的特定离子效应的图像。像氟化物这样的小阴离子，但不是更重的卤化物，对带正电荷的基团表现出强烈的亲和力，顺序为胍基>咪唑基>铵基。相比之下，大的软阴离子，如碘化物，对氨基酸的非极性区域的吸引力较弱。由于卤化物与带正电荷的基团的相互作用具有局部特征，而且不是压倒性的强，因此在水合蛋白质表面也会观察到类似的行为（在附加意义上）。
