Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center, Russian Academy of Sciences, Lobachevsky Str., 2/31, Kazan, 420111, Russian Federation.
A. Butlerov Chemical Institute, Kazan Federal University, Kremlevskaya 18, Kazan, 420008, Russian Federation.
Eur Biophys J. 2022 Jul;51(4-5):375-383. doi: 10.1007/s00249-022-01605-0. Epub 2022 Jun 10.
Diffusive behavior of human serum albumin (HSA) in the presence of Mg and Cu ions was studied by pulsed field gradient nuclear magnetic resonance (PFG NMR) and dynamic light scattering (DLS). According to NMR data yielding measurements of HSA self-diffusion coefficient, a weighted average of the protein monomers and oligomers diffusion mobility in the presence of metal ions was observed. While the short-time collective diffusion measured by DLS showed one type of diffusing species in ion-free HSA solution and two molecular forms of HSA in the presence of metal ions. The light intensity correlation function analysis showed that HSA oligomers have a limited lifetime (lower limit is about 0.4 ms) intermediate between characteristic time scales of PFG NMR and DLS experiments. For a theoretical description of concentration dependence of HSA self- and collective diffusion coefficients, the phenomenological approach based on the frictional formalism of non-equilibrium thermodynamics was used (Vink theory), allowing analysis of the solvent-solute and solute-solute interactions in protein solutions. In the presence of metal ions, a significant increase of HSA protein-protein friction coefficient was shown. Based on theoretical analysis of collective diffusion data, the positive values of second virial coefficients A for HSA monomers were obtained. The A values were found to be higher for the HSA with metal ions compared with the ion-free HSA solution. This is due to the more pronounced contribution of repulsion in protein-protein interactions of HSA monomers in the presence of Mg and Cu ions.
采用脉冲梯度核磁共振（PFG NMR）和动态光散射（DLS）研究了人血清白蛋白（HSA）在 Mg 和 Cu 离子存在下的扩散行为。根据 NMR 数据得出的 HSA 自扩散系数测量结果，观察到蛋白质单体和低聚物在金属离子存在下的扩散迁移率的加权平均值。虽然 DLS 测量的短时间集体扩散在无离子 HSA 溶液中显示出一种扩散物种，而在金属离子存在下显示出 HSA 的两种分子形式。光强相关函数分析表明，HSA 低聚物具有有限的寿命（下限约为 0.4 ms），介于 PFG NMR 和 DLS 实验的特征时间尺度之间。为了对 HSA 自扩散和集体扩散系数的浓度依赖性进行理论描述，使用了基于非平衡热力学摩擦形式主义的唯象方法（Vink 理论），允许分析蛋白质溶液中的溶剂-溶质和溶质-溶质相互作用。在金属离子存在下，HSA 蛋白质-蛋白质摩擦系数显著增加。基于集体扩散数据的理论分析，获得了 HSA 单体的第二维里系数 A 的正值。与无离子 HSA 溶液相比，发现 HSA 与金属离子结合时的 A 值更高。这是由于在 Mg 和 Cu 离子存在下，HSA 单体的蛋白质-蛋白质相互作用中排斥作用的贡献更为明显。
