Yang L, Valdeavella C V, Blatt H D, Pettitt B M
Department of Chemistry, University of Houston, Texas 77204-5641, USA.
Biophys J. 1996 Dec;71(6):3022-9. doi: 10.1016/S0006-3495(96)79495-X.
Four 1-ns molecular dynamics computer simulations of tuftsin, Thr-Lys-Pro-Arg, are analyzed: (1) cis tuftsin in water, (2) trans tuftsin in water, (3) cis tuftsin in 1 M NaCl, and (4) trans tuftsin in 1 M NaCl. Independently of the salt concentration, the trans conformer has a higher dielectric constant than the cis conformer because the former exhibits a more widely distributed charge distribution in space. Independently of the peptide conformation, the presence of salt reduces the dielectric constants of both the peptide and the solvating water molecules because ions, on binding, restrict the motion of other atoms. In contrast to the dielectric constants, neither the peptide conformation nor the salt concentration shows a significant influence on the dielectric relaxation time of water molecules.
对促吞噬素（苏氨酸-赖氨酸-脯氨酸-精氨酸，即Thr-Lys-Pro-Arg）进行了四次1纳秒的分子动力学计算机模拟分析：（1）水中的顺式促吞噬素，（2）水中的反式促吞噬素，（3）1M氯化钠溶液中的顺式促吞噬素，以及（4）1M氯化钠溶液中的反式促吞噬素。与盐浓度无关，反式构象体的介电常数高于顺式构象体，因为前者在空间中表现出更广泛分布的电荷分布。与肽构象无关，盐的存在会降低肽和溶剂化水分子的介电常数，因为离子在结合时会限制其他原子的运动。与介电常数相反，肽构象和盐浓度对水分子的介电弛豫时间均无显著影响。
