Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei 230026, P. R. China.
J Phys Chem B. 2017 Aug 3;121(30):7366-7372. doi: 10.1021/acs.jpcb.7b04314. Epub 2017 Jul 24.
Macromolecular crowding could influence the binding affinity of the polyzwitterion-conjugated proteins. Herein, the hydrolysis of N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide by the poly(carboxybetaine) conjugated α-chymotrypsin (PCT) was employed as a model system to investigate the modulation of the binding affinity of the polyzwitterion-conjugated proteins by the ion-specific effects in the crowded environments. In comparison with the bare α-chymotrypsin (BCT), the binding affinity of the PCT to the peptide is stronger in the dilute solutions but becomes weaker in the crowded environments. Our study demonstrates that the kosmotropic Ac anion is incapable of achieving a stronger enzymatic binding affinity of the PCT than the BCT in the highly crowded environments. By contrast, the binding affinity of the PCT can be enhanced to be stronger than that of the BCT by the chaotropic SCN anion in the crowded environments.
大分子拥挤可能会影响聚两性离子缀合蛋白的结合亲和力。在此，通过聚（羧基甜菜碱）缀合的α-糜蛋白酶（PCT）水解 N-琥珀酰基-丙氨酸-丙氨酸-脯氨酸对硝基苯胺作为模型体系，研究了在拥挤环境中离子特异性效应对聚两性离子缀合蛋白结合亲和力的调节。与裸α-糜蛋白酶（BCT）相比，PCT 与肽的结合亲和力在稀溶液中较强，但在拥挤环境中较弱。我们的研究表明，在高拥挤环境中，亲水分子 Ac 阴离子不能使 PCT 比 BCT 具有更强的酶结合亲和力。相比之下，在拥挤环境中，离于 SCN 阴离子可以增强 PCT 的结合亲和力，使其强于 BCT。
