Faculté des Sciences de Tunis, LR99ES16 Laboratoire Physique de la Matière Molle et de la Modélisation Électromagnétique, Université de Tunis El Manar, 2092, Tunis, Tunisia.
Eur Biophys J. 2021 Sep;50(6):877-887. doi: 10.1007/s00249-021-01542-4. Epub 2021 May 28.
The mixture of poly-L-lysine (PLL) and long-chain PSSNa can lead to the formation of soluble complexes depending on pH, PLL concentration, ionic strength, and temperature. The influence of these stimuli was studied by zetametry, dynamic and ultra-small-angle light scattering, and turbidimetric measurements. First of all, we studied the stoichiometry of complexation, and then considered the influence of salt concentration and temperature on the behavior of the mixture at different pH values. These findings have allowed us to conclude that the polyelectrolyte-polypeptide stoichiometry is controlled by electrostatic interactions between opposite charges. At mass ratios between 1.8 and 2.3 and with net charges close to neutrality, unstable complexes were formed and flocculated due to the hydrophobic attraction leading to macroscopic phase separation. The linear charge density of the complex is also controlled by the ionic strength. Higher CaCl concentrations reduce the complex stability and decrease the charge density, which leads to surface patch binding (SPB) at higher pH. Finally, the electrostatic interactions and strength of hydrogen bonds increased the stabilization of the complexes formed at temperatures lower than 45 °C. At temperatures higher than 45 °C, hydrophobic interactions became more dominant, causing a destabilization of the complexes.
聚-L-赖氨酸（PLL）和长链 PSSNa 的混合物可以根据 pH 值、PLL 浓度、离子强度和温度形成可溶性复合物。通过静电势法、动态和超小角光散射以及浊度测量研究了这些刺激因素的影响。首先，我们研究了络合的化学计量比，然后考虑了盐浓度和温度对不同 pH 值下混合物行为的影响。这些发现使我们能够得出结论，聚电解质-多肽的化学计量比受相反电荷之间的静电相互作用控制。在质量比为 1.8 到 2.3 之间，净电荷接近中性时，由于疏水性吸引导致宏观相分离，形成了不稳定的复合物并絮凝。复合物的线性电荷密度也受到离子强度的控制。较高的 CaCl 浓度降低了复合物的稳定性并降低了电荷密度，这导致在较高 pH 值下发生表面斑块结合 (SPB)。最后，静电相互作用和氢键的强度增加了在低于 45°C 的温度下形成的复合物的稳定性。在高于 45°C 的温度下，疏水性相互作用变得更加占主导地位，导致复合物的不稳定性。
