Physikalische Chemie I, University of Bayreuth, D-95440 Bayreuth, Germany.
J Am Chem Soc. 2010 Mar 10;132(9):3159-63. doi: 10.1021/ja909938c.
The thermodynamics and the driving forces of the adsorption of beta-lactoglobulin on spherical polyelectrolyte brushes (SPB) are investigated by isothermal titration calorimetry (ITC). The SPB consist of a polystyrene core onto which long chains of poly(styrene sulfonate) are grafted. Adsorption isotherms are obtained from measurements by ITC. The analysis by ITC shows clearly that the adsorption process is solely driven by entropy while DeltaH > 0. This finding is in accordance with the proposed mechanism of counterion release: Patches of positive charges on the surface of the proteins become multivalent counterions of the polyelectrolyte chains, thereby releasing the counterions of the protein and the polyelectrolyte. A simple statistical-mechanical model fully corroborates the proposed mechanism. The present analysis shows clearly the fundamental importance of counterion release for protein adsorption on charged interfaces and charged polymeric layers.
通过等温滴定微量热法（ITC）研究了β-乳球蛋白在球形聚电解质刷（SPB）上吸附的热力学和驱动力。SPB 由聚苯乙烯核组成，其上接枝了长链聚苯乙烯磺酸盐。通过 ITC 测量得到吸附等温线。ITC 分析清楚地表明，吸附过程仅由熵驱动，而 DeltaH > 0。这一发现与提出的抗衡离子释放机制一致：蛋白质表面的正电荷斑成为聚电解质链的多价抗衡离子，从而释放蛋白质和聚电解质的抗衡离子。一个简单的统计力学模型充分证实了所提出的机制。本分析清楚地表明，抗衡离子释放对于蛋白质在带电界面和带电聚合物层上的吸附具有重要意义。
