Trevitt Clare R, Yashwanth Kumar D R, Fowler Nicholas J, Williamson Mike P
School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK.
Certara UK Ltd, Level 2-Acero, 1 Concourse Way, Sheffield, S1 3BJ, UK.
Commun Chem. 2024 Feb 28;7(1):44. doi: 10.1038/s42004-024-01127-0.
Protein solubility and stability depend on the co-solutes present. There is little theoretical basis for selection of suitable co-solutes. Some guidance is provided by the Hofmeister series, an empirical ordering of anions according to their effect on solubility and stability; and by osmolytes, which are small organic molecules produced by cells to allow them to function in stressful environments. Here, NMR titrations of the protein barnase with Hofmeister anions and osmolytes are used to measure and locate binding, and thus to separate binding and bulk solvent effects. We describe a rationalisation of Hofmeister (and inverse Hofmeister) effects, which is similar to the traditional chaotrope/kosmotrope idea but based on solvent fluctuation rather than water withdrawal, and characterise how co-solutes affect protein stability and solubility, based on solvent fluctuations. This provides a coherent explanation for solute effects, and points towards a more rational basis for choice of excipients.
蛋白质的溶解度和稳定性取决于存在的共溶质。选择合适的共溶质几乎没有理论依据。霍夫迈斯特序列提供了一些指导，它是根据阴离子对溶解度和稳定性的影响进行的经验排序；渗透剂也提供了一些指导，渗透剂是细胞产生的小有机分子，使细胞能够在压力环境中发挥作用。在这里，用霍夫迈斯特阴离子和渗透剂对核糖核酸酶进行核磁共振滴定，以测量和定位结合，从而区分结合和本体溶剂效应。我们描述了对霍夫迈斯特（和反霍夫迈斯特）效应的一种合理化解释，它类似于传统的离液剂/促溶剂概念，但基于溶剂波动而非水的析出，并基于溶剂波动描述了共溶质如何影响蛋白质的稳定性和溶解度。这为溶质效应提供了一个连贯的解释，并为辅料的选择指明了一个更合理的基础。
