1
|
Gu R, Guo J, Zhang S, Zhou J, Wang J, Cohen Stuart MA, Wang M. Effects of catechol grafting on chitosan-based coacervation and adhesion. Int J Biol Macromol 2024; 267:131662. [PMID: 38636754 DOI: 10.1016/j.ijbiomac.2024.131662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/01/2024] [Accepted: 04/15/2024] [Indexed: 04/20/2024]
Abstract
In this study, we investigated detailedly the contribution of catechol in tuning the formation and adhesive properties of coacervates. We have constructed a series of catechol-grafted Chitosan (Chitosan-C), and investigated their coacervation with gum arabic (GA) and the corresponding adhesion. We demonstrate that, increasing catechol grafting ratio from 0 %-44 % impacted the coacervation moderately, while enhanced the adhesion of the coacervate up to 438 % when the catechol faction was 37 %. Further increasing the grafting ratio to 55 % led to precipitated coacervates associated with a declined adhesion. Our findings identify the optimal grafting threshold for coacervation and adhesion, providing insights into the underlying mechanism of coacervate binding. Moreover, the catechol enhancement on adhesion of coacervates tolerates different substrates and diverse polyelectrolyte pairs. The revealed principles shall be helpful for designing adhesive coacervates and boosting their applications in various industrial and biomedical areas.
Collapse
Affiliation(s)
- Runkang Gu
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
| | - Jiangtao Guo
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
| | - Shiting Zhang
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
| | - Jin Zhou
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
| | - Junyou Wang
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
| | - Martien A Cohen Stuart
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
| | - Mingwei Wang
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China.
| |
Collapse
|
2
|
Torres PB, Baldor S, Quiroga E, Ramirez-Pastor AJ, Spelzini D, Boeris V, Narambuena CF. Modulation of the electrostatic potential around α-lactalbumin using oligoelectrolyte chains, pH and salt concentration. SOFT MATTER 2024; 20:2100-2112. [PMID: 38348915 DOI: 10.1039/d3sm01414b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
In this study, we conducted a comprehensive computational investigation of the interaction between α-lactalbumin, a small globular protein, and strong anionic oligoelectrolyte chains with a polymerization degree from 2 to 9. Both the protein and oligoelectrolyte chains are represented using coarse-grained models, and their properties were calculated by the Monte Carlo method under constant pH conditions. We were able to estimate the effects of this interaction on the electrostatic potential around the protein. At acidic pH, the protein had a net positive charge; therefore, the electrostatic potential around it was also positive. To neutralize or reverse this electrostatic potential, oligoelectrolyte chains with a minimum size of six monomers were necessary. Simultaneously, low salt concentrations were required as elevated salt levels led to a significant attenuation of the electrostatic interactions and the corresponding electrostatic potential.
Collapse
Affiliation(s)
- Paola B Torres
- Grupo de Bionanotecnologia y Sistemas Complejos. Infap-CONICET & Facultad Regional San Rafael, Universidad Tecnológica Nacional, Av. General Urquiza 314 C.P, M5600, San Rafael, Argentina.
| | - Sofia Baldor
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Área Fisicoquímica, Universidad Nacional de Rosario - CONICET, Rosario 2000, Argentina
| | - Evelina Quiroga
- Instituto de Física Aplicada (INFAP), Universidad Nacional de San Luis-CONICET, San Luis D5700BWS, Argentina
| | - Antonio Jose Ramirez-Pastor
- Instituto de Física Aplicada (INFAP), Universidad Nacional de San Luis-CONICET, San Luis D5700BWS, Argentina
| | - Dario Spelzini
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Área Fisicoquímica, Universidad Nacional de Rosario - CONICET, Rosario 2000, Argentina
| | - Valeria Boeris
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Área Fisicoquímica, Universidad Nacional de Rosario - CONICET, Rosario 2000, Argentina
| | - Claudio F Narambuena
- Grupo de Bionanotecnologia y Sistemas Complejos. Infap-CONICET & Facultad Regional San Rafael, Universidad Tecnológica Nacional, Av. General Urquiza 314 C.P, M5600, San Rafael, Argentina.
| |
Collapse
|
3
|
Staňo R, van Lente J, Lindhoud S, Košovan P. Sequestration of Small Ions and Weak Acids and Bases by a Polyelectrolyte Complex Studied by Simulation and Experiment. Macromolecules 2024; 57:1383-1398. [PMID: 38370910 PMCID: PMC10867894 DOI: 10.1021/acs.macromol.3c01209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 02/20/2024]
Abstract
Mixing of oppositely charged polyelectrolytes can result in phase separation into a polymer-poor supernatant and a polymer-rich polyelectrolyte complex (PEC). We present a new coarse-grained model for the Grand-reaction method that enables us to determine the composition of the coexisting phases in a broad range of pH and salt concentrations. We validate the model by comparing it to recent simulations and experimental studies, as well as our own experiments on poly(acrylic acid)/poly(allylamine hydrochloride) complexes. The simulations using our model predict that monovalent ions partition approximately equally between both phases, whereas divalent ones accumulate in the PEC phase. On a semiquantitative level, these results agree with our own experiments, as well as with other experiments and simulations in the literature. In the sequel, we use the model to study the partitioning of a weak diprotic acid at various pH values of the supernatant. Our results show that the ionization of the acid is enhanced in the PEC phase, resulting in its preferential accumulation in this phase, which monotonically increases with the pH. Currently, this effect is still waiting to be confirmed experimentally. We explore how the model parameters (particle size, charge density, permittivity, and solvent quality) affect the measured partition coefficients, showing that fine-tuning of these parameters can make the agreement with the experiments almost quantitative. Nevertheless, our results show that charge regulation in multivalent solutes can potentially be exploited in engineering the partitioning of charged molecules in PEC-based systems at various pH values.
Collapse
Affiliation(s)
- Roman Staňo
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Vienna
Doctoral School in Physics, University of
Vienna, Boltzmanngasse
5, 1090 Vienna, Austria
| | - Jéré
J. van Lente
- Department
of Molecules & Materials, University
of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Saskia Lindhoud
- Department
of Molecules & Materials, University
of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Peter Košovan
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 40 Prague 2, Czech Republic
| |
Collapse
|
4
|
Popova TO, Zhulina EB, Borisov OV. Interaction of Polyanionic and Polycationic Brushes with Globular Proteins and Protein-like Nanocolloids. Biomimetics (Basel) 2023; 8:597. [PMID: 38132536 PMCID: PMC10741738 DOI: 10.3390/biomimetics8080597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 11/25/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
A large number of experimental studies have demonstrated that globular proteins can be absorbed from the solution by both polycationic and polyanionic brushes when the net charge of protein globules is of the same or of the opposite sign with respect to that of brush-forming polyelectrolyte chains. Here, we overview the results of experimental studies on interactions between globular proteins and polycationic or polyanionic brushes, and present a self-consistent field theoretical model that allows us to account for the asymmetry of interactions of protein-like nanocolloid particles comprising weak (pH-sensitive) cationic and anionic groups with a positively or negatively charged polyelectrolyte brush. The position-dependent insertion free energy and the net charge of the particle are calculated. The theoretical model predicts that if the numbers of cationic and anionic ionizable groups of the protein are approximately equal, then the interaction patterns for both cationic and anionic brushes at equal offset on the "wrong side" from the isoelectric point (IEP), i.e., when the particle and the brush charge are of the same sign, are similar. An essential asymmetry in interactions of particles with polycationic and polyanionic brushes is predicted when fractions of cationic and anionic groups differ significantly. That is, at a pH above IEP, the anionic brush better absorbs negatively charged particles with a larger fraction of ionizable cationic groups and vice versa.
Collapse
Affiliation(s)
- Tatiana O. Popova
- Chemical Engineering Center, National Research University ITMO, 199004 St. Petersburg, Russia;
- Institute of Macromolecular Compoundsof the Russian Academy of Sciences, 199004 St. Petersburg, Russia;
| | - Ekaterina B. Zhulina
- Institute of Macromolecular Compoundsof the Russian Academy of Sciences, 199004 St. Petersburg, Russia;
| | - Oleg V. Borisov
- Chemical Engineering Center, National Research University ITMO, 199004 St. Petersburg, Russia;
- Institute of Macromolecular Compoundsof the Russian Academy of Sciences, 199004 St. Petersburg, Russia;
- CNRS, Université de Pau et des Pays de l’Adour UMR 5254, Institut des Sciences Analytiques et de Physico-Chimie Pour l’Environnement et les Matériaux, 64053 Pau, France
| |
Collapse
|
5
|
Merzougui CE, Aimar P, Bacchin P, Causserand C. pH-Dependent Adsorption of Human Serum Albumin Protein on a Polystyrene-Block-Poly(acrylic acid)-Coated PVDF Membrane. MEMBRANES 2023; 13:886. [PMID: 38132890 PMCID: PMC10744623 DOI: 10.3390/membranes13120886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 12/23/2023]
Abstract
This study reports the investigation of human serum albumin (HSA) adsorption on a poy-styrene-block-poly(acrylic acid) (PS-b-PAA)-coated PVDF membrane, which is a potential smart material for biomedical applications. First, copolymer coating on the membrane surface was successfully performed, due to the hydrophobic interaction of the PS anchoring group with the PVDF membrane. This was confirmed by Fourier transform infrared spectroscopy (FTIR) characterization of the membrane. Then, HSA adsorption onto the coated membrane was assessed and was proved to be strongly dependent on the pH of the protein solution. Indeed, both FTIR mapping and mass balance calculation using UV-visible spectroscopy displayed a greater HSA adsorption on the membrane at pH 5, even though it still took place at higher pH, but to a lower extent. Afterwards, an ionic strength influence study evinced the role of electrostatic interactions between HSA and the PAA layer on HSA adsorption. Dead-end filtration of HSA through the coated membrane confirmed the pH dependence of HSA adsorption on the coated membrane.
Collapse
Affiliation(s)
- Charaf-Eddine Merzougui
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INP, UPS, 31062 Toulouse, France; (P.A.); (P.B.)
| | | | | | - Christel Causserand
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INP, UPS, 31062 Toulouse, France; (P.A.); (P.B.)
| |
Collapse
|
6
|
Zhou J, Cai Y, Wan Y, Wu B, Liu J, Zhang X, Hu W, Cohen Stuart MA, Wang J. Protein separation by sequential selective complex coacervation. J Colloid Interface Sci 2023; 650:2065-2074. [PMID: 37355354 DOI: 10.1016/j.jcis.2023.06.119] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/21/2023] [Accepted: 06/17/2023] [Indexed: 06/26/2023]
Abstract
In food manufacturing and particular biomedical products selected proteins are often required. Obtaining the desired proteins in a pure form from natural resources is therefore important, but often very challenging. Herein, we design a sequential coacervation process that allows to efficiently isolate and purify proteins with different isoelectric points (pIs) from a mixed solution, namely Bovine Serum Albumin (BSA, pI = 4.9) and Peroxidase from Horseradish (HRP, pI = 7.2). The key to separation is introducing a suitable polyelectrolyte that causes selective complex coacervation at appropriate pH and ionic strength. Specifically, polyethyleneimine (PEI), when added into the mixture at pH 6.0, produces a coacervation which exclusively contains BSA, leading to a supernatant solution containing 100 % HRP with a purity of 91 %. After separating the dilute and dense phases, BSA is recovered by adding poly(acrylic acid) (PAA) to the concentrated phase, which displaces BSA from the complex because it interacts more strongly with PEI. The supernatant phase after this step contains approximately 75 % of the initial amount of BSA with a purity of 99 %. Our results confirm that coacervation under well-defined conditions can be selective, enabling separation of proteins with adequate purity. Therefore, the established approach demonstrates a facile and sustainable strategy with potential for protein separation at industrial scale.
Collapse
Affiliation(s)
- Jin Zhou
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Ying Cai
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Yuting Wan
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Bohang Wu
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Jinbo Liu
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Xinxin Zhang
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Weiwei Hu
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, People's Republic of China.
| | - Martien A Cohen Stuart
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China
| | - Junyou Wang
- State-Key Laboratory of Chemical Engineering, and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, People's Republic of China.
| |
Collapse
|
7
|
Simončič M, Hritz J, Lukšič M. Biomolecular Complexation on the "Wrong Side": A Case Study of the Influence of Salts and Sugars on the Interactions between Bovine Serum Albumin and Sodium Polystyrene Sulfonate. Biomacromolecules 2022; 23:4412-4426. [PMID: 36134887 PMCID: PMC9554918 DOI: 10.1021/acs.biomac.2c00933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/12/2022] [Indexed: 11/28/2022]
Abstract
In the protein purification, drug delivery, food industry, and biotechnological applications involving protein-polyelectrolyte complexation, proper selection of co-solutes and solution conditions plays a crucial role. The onset of (bio)macromolecular complexation occurs even on the so-called "wrong side" of the protein isoionic point where both the protein and the polyelectrolyte are net like-charged. To gain mechanistic insights into the modulatory role of salts (NaCl, NaBr, and NaI) and sugars (sucrose and sucralose) in protein-polyelectrolyte complexation under such conditions, interaction between bovine serum albumin (BSA) and sodium polystyrene sulfonate (NaPSS) at pH = 8.0 was studied by a combination of isothermal titration calorimetry, fluorescence spectroscopy, circular dichroism, and thermodynamic modeling. The BSA-NaPSS complexation proceeds by two binding processes (first, formation of intrapolymer complexes and then formation of interpolymer complexes), both driven by favorable electrostatic interactions between the negatively charged sulfonic groups (-SO3-) of NaPSS and positively charged patches on the BSA surface. Two such positive patches were identified, each responsible for one of the two binding processes. The presence of salts screened both short-range attractive and long-range repulsive electrostatic interactions between both macromolecules, resulting in a nonmonotonic dependence of the binding affinity on the total ionic strength for both binding processes. In addition, distinct anion-specific effects were observed (NaCl < NaBr < NaI). The effect of sugars was less pronounced: sucrose had no effect on the complexation, but its chlorinated analogue, sucralose, promoted it slightly due to the screening of long-range repulsive electrostatic interactions between BSA and NaPSS. Although short-range non-electrostatic interactions are frequently mentioned in the literature in relation to BSA or NaPSS, we found that the main driving force of complexation on the "wrong side" are electrostatic interactions.
Collapse
Affiliation(s)
- Matjaž Simončič
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia
| | - Jozef Hritz
- Central
European Institute of Technology, Masaryk
University, Kamenice
5, CZ-62500 Brno, Czechia
- Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice
5, CZ-62500 Brno, Czechia
| | - Miha Lukšič
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia
| |
Collapse
|
8
|
He X, Li M, Liu Y, Nian Y, Hu B. Purification of Egg White Lysozyme Determines the Downstream Fibrillation of Protein and Co-assembly with Phytochemicals to Form Edible Hydrogels Regulating the Lipid Metabolism. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:9432-9441. [PMID: 35876899 DOI: 10.1021/acs.jafc.2c03363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although the synthetic chemistry or synthetic biological systems have already shown the power of biomaterials engineering, natural bioresource matter is still a valuable library of raw ingredients for the production of biomaterials, in particular, the edible ones. However, the influence of upstream isolation and purification of the raw materials on their performance in the downstream processing procedures is still unexplored, which is essential for the engineering of biomaterials. Based on the comparison of conventional techniques, heating-induced precipitation combined with resin-blending ion exchange was developed as a simple and cheap method for the utilization of egg whites to produce the lysozyme that is found to be exclusively feasible for fibrillation. Even with similar purities, only the lysozyme prepared by this method could be utilized to form ordered linear aggregate fibrils. Fibrillation was recently pursued as a new approach to utilize bioresource mass for high-tech end-products. Phytochemicals, totally replacing salts, induced the lysozyme fibrils to form hydrogels spontaneously, which was further demonstrated in an in vivo study to prevent obesity induced by a high-fat diet (HFD) by reducing lipid absorption and lipogenesis, promoting energy expenditure, and inhibiting inflammation. The agri-food bioresource was successfully employed as a proof of concept in edible biomedical materials for the regulation of lipid metabolism.
Collapse
Affiliation(s)
- Xiaoqian He
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Min Li
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Yanhua Liu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Yingqun Nian
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Bing Hu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, P.R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510640, China
| |
Collapse
|
9
|
Simončič M, Lukšič M. Modulating Role of Co-Solutes in Complexation between Bovine Serum Albumin and Sodium Polystyrene Sulfonate. Polymers (Basel) 2022; 14:1245. [PMID: 35335575 PMCID: PMC8953846 DOI: 10.3390/polym14061245] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/12/2022] [Accepted: 03/18/2022] [Indexed: 11/28/2022] Open
Abstract
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: pHc corresponding to the formation of the soluble complexes, pHΦ corresponding to the formation of the insoluble complexes, and pHopt 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.
Collapse
Affiliation(s)
- Matjaž Simončič
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Miha Lukšič
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| |
Collapse
|