Effect of sodium chloride on solute-solvent interactions in aqueous polyethylene glycol-sodium sulfate two-phase systems


Partition behavior of eight small organic compounds and six proteins was examined in poly(ethylene glycol)-8000-sodium sulfate aqueous two-phase systems containing 0.215 M NaCl and 0.5 M osmolyte (sorbitol, sucrose, TMAO) and poly(ethylene glycol)-10000-sodium sulfate-0.215 M NaCl system, all in 0.01 M sodium phosphate buffer, pH 6.8. The differences between the solvent properties of the coexisting phases (solvent dipolarity/polarizability, hydrogen bond donor acidity, and hydrogen bond acceptor basicity) were characterized with solvatochromic dyes using the solvatochromic comparison method. Differences between the electrostatic properties of the phases were determined by analysis of partitioning of sodium salts of dinitrophenylated (DNP-) amino acids with aliphatic alkyl side-chain. The partition coefficients of all compounds examined (including proteins) were described in terms of solute-solvent interactions. The results obtained in the study show that solute-solvent interactions of nonionic organic compounds and proteins in polyethylene glycol-sodium sulfate aqueous two-phase system change in the presence of NaCl additive. (C) 2015 Elsevier B.V. All rights reserved.



subject category

Biochemistry & Molecular Biology; Chemistry


da Silva, NR; Ferreira, LA; Madeira, PP; Teixeira, JA; Uversky, VN; Zaslavsky, BY

our authors


Nuno da Silva acknowledges the financial support by Fundacao para a Ciencia e a Tecnologia (FCT) of the Portuguese's Ministry for Science, Technology and Higher Education, in the framework of the Operational Program COMPETE (PTDC/EQU-FTT/120332/2010) and Fundacao para a Ciencia e Tecnologia the strategic funding of UID/BIO/04469/2013.; Pedro P. Madeira acknowledges the financial support in part provided by (i) FCT/MEC, FEDER under Program PT2020 (Project UID/EQU/50020/2013) and (ii) QREN, ON2 and FEDER, under Program COMPETE (Project NORTE-07-0124-FEDER-0000011).

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