International Laser Center, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia.
Department of Physics, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia.
Colloids Surf B Biointerfaces. 2016 Oct 1;146:507-13. doi: 10.1016/j.colsurfb.2016.06.049. Epub 2016 Jun 29.
We studied the interaction between bovine serum albumin (BSA) and lanthanide ions in aqueous solution in the 4.0÷9.5pH range. A strong increase of the solution turbidity was observed at pH values exceeding 6, which corresponds to the formation of Ln(OH)3 nanoparticles, while no changes were observed near the isoelectric point of BSA (pH 4.7). The results of the dynamic light scattering and protein adsorption measurements clearly demonstrated that the observed turbidity enhancement was caused by albumin sorption on the surface of Ln(OH)3 and colloid particles bridging via adsorbed protein molecules. Upon pH increase from 4.5 to 6.5, albumin adsorption on lanthanide colloids was observed, while the following increase of pH from 6.5 to 9.5 led to protein desorption. The predominant role of the electrostatic interactions in the adsorption and desorption processes were revealed in the zeta-potential measurements. No reversibility was observed upon decreasing pH from 9.5 to 4.5 that was suggested to be due to the other interaction mechanisms present in the system. It was shown that while for all lanthanide ions the interaction mechanism with BSA was similar, its manifestation in the optical properties of the system was significantly different. This was interpreted as a consequence of the differences in lanthanides hydrolysis constants.
我们研究了牛血清白蛋白（BSA）与水溶液中镧系离子在 4.0÷9.5pH 值范围内的相互作用。在 pH 值超过 6 时，观察到溶液浊度强烈增加，这对应于 Ln(OH)3 纳米颗粒的形成，而在 BSA 的等电点（pH 4.7）附近则没有观察到变化。动态光散射和蛋白质吸附测量的结果清楚地表明，观察到的浊度增强是由白蛋白吸附在 Ln(OH)3 表面和通过吸附蛋白质分子桥接的胶体颗粒上引起的。当 pH 值从 4.5 增加到 6.5 时，观察到白蛋白在镧系胶体上的吸附，而当 pH 值从 6.5 增加到 9.5 时，导致蛋白质解吸。在 zeta 电位测量中揭示了吸附和脱附过程中静电相互作用的主要作用。当 pH 值从 9.5 降低到 4.5 时，没有观察到可逆性，这被认为是由于系统中存在其他相互作用机制。结果表明，尽管所有镧系离子与 BSA 的相互作用机制相似，但在系统的光学性质中的表现却有很大差异。这被解释为镧系元素水解常数差异的结果。
