Phase stability of aqueous mixtures of bovine serum albumin with low molecular mass salts in presence of polyethylene glycol

Džudžević Čančar, Hurija (author), Belak Vivod, Matic (author), Vlachy, Vojko (author), Lukšič, Miha (author)

The stability of bovine serum albumin (BSA) solutions against phase separation caused by cooling the system is studied under the combined influence of added poly(ethylene glycol) (PEG) and alkali halide salts in water as solvent. The phase stability of the system depends on the concentration of the added PEG and its molecular mass, the concentration of the low molecular mass electrolyte and its nature, as also on the pH of the solution. More specifically, the addition of NaCl to the BSA-PEG mixture promotes phase separation at pH = 4.0, where BSA carries the net positive charge in aqueous solution, and it increases the stability of the solution at pH = 4.6, i.e., near the isoionic point of the protein. Moreover, at pH = 4.6, the cloud-point temperature decreases in the order from NaF to NaI and from LiCl to CsCl. The order of the salts at pH = 4.0 is exactly reversed: LiCl and NaF show the weakest effect on the cloud-point temperature and the strongest decrease in stability is caused by RbCl and NaNO$_3$. An attempt is made to correlate these observations with the free energies of hydration of the added salt ions and with the effect of adsorption of salt ions on the protein surface on the protein–protein interactions. Kosmotropic salt ions decrease the phase stability of BSA-PEG-salt solutions at pH < pI, while exactly the opposite is true at pH = pI.

• Language: English
• Keywords: bovine serum albumin solution, polyethylene glycol, cloud–point temperature, solubility, salt specific effects
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 8 str.
• Numbering: Vol. 349, art. 118477
• PID: 20.500.12556/RUL-137624
• UDC: 577.322
• ISSN on article: 0167-7322
• DOI: 10.1016/j.molliq.2022.118477
• COBISS.SI-ID: 93209859
• Publication date in RUL: 23.06.2022

Record is a part of a journal

• Title: Journal of molecular liquids
• Shortened title: J. mol. liq.
• Publisher: Elsevier
• ISSN: 0167-7322
• COBISS.SI-ID: 15382277

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: goveji serumski albumin, vodne raztopine, fazna stabilnost, polietilen glikol, topnost