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Thermodynamic Analysis of the Uptake of a Protein in a Spherical Polyelectrolyte Brush.
Macromolecular Rapid Communications ( IF 4.2 ) Pub Date : 2019-11-07 , DOI: 10.1002/marc.201900421
Jacek Walkowiak 1 , Yan Lu 2, 3 , Michael Gradzielski 4 , Stefan Zauscher 5 , Matthias Ballauff 2
Affiliation  

A thermodynamic study of the adsorption of Human Serum Albumin (HSA) onto spherical polyelectrolyte brushes (SPBs) by isothermal titration calorimetry (ITC) is presented. The SPBs are composed of a solid polystyrene core bearing long chains of poly(acrylic acid). ITC measurements done at different temperatures and ionic strengths lead to a full set of thermodynamicbinding constants together with the enthalpies and entropies of binding. The adsorption of HSA onto SPBs is described with a two-step model. The free energy of binding ΔGb depends only weakly on temperature because of a marked compensation of enthalpy by entropy. Studies of the adsorbed HSA by Fourier transform infrared spectroscopy (FT-IR) demonstrate no significant disturbance in the secondary structure of the protein. The quantitative analysis demonstrates that counterion release is the major driving force for adsorption in a process where proteins become multivalent counterions of the polyelectrolyte chains upon adsorption. A comparison with the analysis of other sets of data related to the binding of HSA to polyelectrolytes demonstrates that the cancellation of enthalpy and entropy is a general phenomenon that always accompanies the binding of proteins to polyelectrolytes dominated by counterion release.

中文翻译:

球形聚电解质刷中蛋白质吸收的热力学分析。

通过等温滴定热法(ITC)对人血清白蛋白(HSA)在球形聚电解质刷(SPB)上的吸附进行了热力学研究。SPB由带有聚丙烯酸长链的固态聚苯乙烯芯组成。在不同温度和离子强度下进行的ITC测量会产生全套的热力学结合常数,以及结合的焓和熵。用两步模型描述了HSA在SPB上的吸附。结合ΔGb的自由能仅弱地依赖于温度,这是因为熵显着地补偿了焓。通过傅立叶变换红外光谱(FT-IR)对吸附的HSA的研究表明,蛋白质的二级结构没有明显的干扰。定量分析表明,在蛋白质吸附后成为聚电解质链的多价抗衡离子的过程中,抗衡离子的释放是吸附的主要驱动力。与与HSA与聚电解质结合有关的其他数据集的分析比较表明,焓和熵的消除是一种普遍现象,始终伴随着蛋白质与反离子释放为主的聚电解质结合。
更新日期:2019-11-07
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