Modulating role of co-solutes in complexation between bovine serum albumin and sodium polystyrene sulfonate

Simončič, Matjaž (author), Lukšič, Miha (author)

The action of three types of co-solutes: (i) salts (NaCl, NaBr, NaI), (ii) polymer (polyethylene glycol; PEG-400, PEG-3000, PEG-20000), and (iii) sugars (sucrose, sucralose) on the complexation between bovine serum albumin (BSA) and sodium polystyrene sulfonate (NaPSS) was studied. Three critical pH parameters were extracted from the pH dependence of the solution’s turbidity: pH$_c$ corresponding to the formation of the soluble complexes, pH$_Φ$ corresponding to the formation of the insoluble complexes, and pH$_{opt}$ corresponding to the charge neutralization of the complexes. In the presence of salts, the formation of soluble and insoluble complexes as well as the charge neutralization of complexes was hindered, which is a consequence of the electrostatic screening of attractive interactions between BSA and NaPSS. Distinct anion-specific trends were observed in which the stabilizing effect of the salt increased in the order: NaCl < NaBr < NaI. The presence of PEG, regardless of its molecular weight, showed no measurable effect on the formation of soluble complexes. PEG-400 and PEG-3000 showed no effect on the formation of insoluble complexes, but PEG-20000 in high concentrations promoted their formation due to the molecular crowding effect. The presence of sugar molecules had little effect on BSA-NaPSS complexation. Sucralose showed a minor stabilizing effect with respect to the onset of complex formation, which was due to its propensity to the protein surface. This was confirmed by the fluorescence quenching assay (Stern-Volmer relationship) and all-atom MD simulations. This study highlights that when evaluating the modulatory effect of co-solutes on protein-polyelectrolyte interactions, (co-solute)-protein interactions and their subsequent impact on protein aggregation must also be considered.

• Language: English
• Keywords: protein-polyelectrolyte complexation, solid-liquid phase separation, sucrose, sucralose, molecular crowding, electrostatic sreening, protein-PE complexation
• 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: 22 str.
• Numbering: Vol. 14, iss. 6, art. 1245
• PID: 20.500.12556/RUL-137517
• UDC: 577.322
• ISSN on article: 2073-4360
• DOI: 10.3390/polym14061245
• COBISS.SI-ID: 101645315
• Publication date in RUL: 20.06.2022

Record is a part of a journal

• Title: Polymers
• Shortened title: Polymers
• Publisher: MDPI
• ISSN: 2073-4360
• COBISS.SI-ID: 517951257

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 19.03.2022

Secondary language

• Language: Slovenian
• Keywords: kompleksacija protein-polielektrolit, fazna separacija trdno-tekoče, saharoza, sukraloza, molekulska gneča, elektrostatsko senčenje