Bucciarelli Saskia, Mahmoudi Najet, Casal-Dujat Lucía, Jéhannin Marie, Jud Corinne, Stradner Anna
Physical Chemistry, Department of Chemistry, Lund University , SE-22100 Lund, Sweden.
Adolphe Merkle Institute (AMI), University of Fribourg , CH-1700 Fribourg, Switzerland.
J Phys Chem Lett. 2016 May 5;7(9):1610-5. doi: 10.1021/acs.jpclett.6b00593. Epub 2016 Apr 18.
Investigating proteins with techniques such as NMR or neutron scattering frequently requires the partial or complete substitution of D2O for H2O as a solvent, often tacitly assuming that such a solvent substitution does not significantly alter the properties of the protein. Here, we report a systematic investigation of the solvent isotope effect on the phase diagram of the lens protein γB-crystallin in aqueous solution as a model system exhibiting liquid-liquid phase separation. We demonstrate that the observed strong variation of the critical temperature Tc can be described by the extended law of corresponding states for all H2O/D2O ratios, where scaling of the temperature by Tc or the reduced second virial coefficient accurately reproduces the binodal, spinodal, and osmotic compressibility. These findings highlight the impact of H2O/D2O substitution on γB-crystallin properties and warrant further investigations into the universality of this phenomenon and its underlying mechanisms.
使用核磁共振（NMR）或中子散射等技术研究蛋白质时，通常需要用重水（D2O）部分或完全替代水（H2O）作为溶剂，人们常常默认这种溶剂替代不会显著改变蛋白质的性质。在此，我们报告了一项关于溶剂同位素效应的系统研究，该效应作用于晶状体蛋白γB-晶状体蛋白在水溶液中的相图，这是一个表现出液-液相分离的模型系统。我们证明，对于所有H2O/D2O比例，观察到的临界温度Tc的强烈变化可以用对应态的扩展定律来描述，其中用Tc对温度进行标度或用约化第二维里系数进行标度能够准确再现双节线、旋节线和渗透压缩性。这些发现突出了H2O/D2O替代对γB-晶状体蛋白性质的影响，并值得进一步研究这一现象的普遍性及其潜在机制。
