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Pineda S, Staňo R, Murmiliuk A, Blanco PM, Montes P, Tošner Z, Groborz O, Pánek J, Hrubý M, Štěpánek M, Košovan P. Charge Regulation Triggers Condensation of Short Oligopeptides to Polyelectrolytes. JACS AU 2024; 4:1775-1785. [PMID: 38818083 PMCID: PMC11134362 DOI: 10.1021/jacsau.3c00668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/24/2024] [Accepted: 02/26/2024] [Indexed: 06/01/2024]
Abstract
Electrostatic interactions between charged macromolecules are ubiquitous in biological systems, and they are important also in materials design. Attraction between oppositely charged molecules is often interpreted as if the molecules had a fixed charge, which is not affected by their interaction. Less commonly, charge regulation is invoked to interpret such interactions, i.e., a change of the charge state in response to a change of the local environment. Although some theoretical and simulation studies suggest that charge regulation plays an important role in intermolecular interactions, experimental evidence supporting such a view is very scarce. In the current study, we used a model system, composed of a long polyanion interacting with cationic oligolysines, containing up to 8 lysine residues. We showed using both simulations and experiments that while these lysines are only weakly charged in the absence of the polyanion, they charge up and condense on the polycations if the pH is close to the pKa of the lysine side chains. We show that the lysines coexist in two distinct populations within the same solution: (1) practically nonionized and free in solution; (2) highly ionized and condensed on the polyanion. Using this model system, we demonstrate under what conditions charge regulation plays a significant role in the interactions of oppositely charged macromolecules and generalize our findings beyond the specific system used here.
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Affiliation(s)
- Sebastian
P. Pineda
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 40, Czech Republic
| | - Roman Staňo
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, Vienna 1090, Austria
- Vienna
Doctoral School in Physics, University of
Vienna, Boltzmanngasse 5, Vienna 1090, Austria
| | - Anastasiia Murmiliuk
- Jülich
Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstraße 1, Garching 85748, Germany
| | - Pablo M. Blanco
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 40, Czech Republic
- Department
of Material Science and Physical Chemistry, Research Institute of
Theoretical and Computational Chemistry (IQTCUB), University of Barcelona, C/Martí i Franquès 1, Barcelona 08028, Spain
- Department of Physics, NTNU - Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Patricia Montes
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 40, Czech Republic
| | - Zdeněk Tošner
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 40, Czech Republic
| | - Ondřej Groborz
- Institute
of Macromolecular Chemistry AS CR, Heyrovský square 2, 162 06 Prague 6, Czech Republic
| | - Jiří Pánek
- Institute
of Macromolecular Chemistry AS CR, Heyrovský square 2, 162 06 Prague 6, Czech Republic
| | - Martin Hrubý
- Institute
of Macromolecular Chemistry AS CR, Heyrovský square 2, 162 06 Prague 6, Czech Republic
| | - Miroslav Štěpánek
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 40, Czech Republic
| | - Peter Košovan
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 40, Czech Republic
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Chen Q, Lai S, Dong L, Liu Y, Pan D, Wu Z, Wu Z, Zhou Y, Ren Y, Zhang J, Liu L, Liu L. Characterization and determination of casein glycomacropeptide in dairy products by UHPLC-MS/MS based on its characteristic peptide. Food Chem 2024; 430:137049. [PMID: 37544157 DOI: 10.1016/j.foodchem.2023.137049] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 07/25/2023] [Accepted: 07/27/2023] [Indexed: 08/08/2023]
Abstract
The ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS) method was built to quantify the casein glycomacropeptide (CGMP) in bovine dairy products accurately based on targeted proteomics. Qualitative analysis of theoretical peptides was carried out using high-resolution mass spectrometry (HRMS) and protein software. Isotope-labeled characteristic peptides were acquired via the labeled amino acid condensation method to correct the matrix effects. Peptide MAIPPK was the representative characteristic peptide for distinguishing the CGMP from κ-casein through trypsin digestion. After optimizing the pre-treatment conditions, the final 8% oxidant concentration was selected and the 10% formic acid concentration with 2.5 h oxidation time. Moreover, the results of methodological verification showed that the recovery rate was 103.7%, meanwhile the precision of inter-day and intra-day was less than 5%. In conclusion, the research demonstrated the characteristic peptide MAIPPK could quantitatively applied to detect CGMP in dairy products.
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Affiliation(s)
- Qin Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China
| | - Shiyun Lai
- Hangzhou Pupai Technology Co., Ltd, Hangzhou 310000, China
| | - Lezhen Dong
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China
| | - Yahui Liu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China
| | - Daodong Pan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China
| | - Zhen Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China
| | - Zufang Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China
| | - Ying Zhou
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Yiping Ren
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Jingshun Zhang
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China.
| | - Lingyi Liu
- Department of Food Science and Technology, University of Nebraska-Lincoln, 68588 NE, USA
| | - Lianliang Liu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Animal Protein Deep Processing Technology of Zhejiang, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, School of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang, PR China.
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Blanco PM, Narambuena CF, Madurga S, Mas F, Garcés JL. Unusual Aspects of Charge Regulation in Flexible Weak Polyelectrolytes. Polymers (Basel) 2023; 15:2680. [PMID: 37376324 DOI: 10.3390/polym15122680] [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: 05/22/2023] [Revised: 06/07/2023] [Accepted: 06/10/2023] [Indexed: 06/29/2023] Open
Abstract
This article reviews the state of the art of the studies on charge regulation (CR) effects in flexible weak polyelectrolytes (FWPE). The characteristic of FWPE is the strong coupling of ionization and conformational degrees of freedom. After introducing the necessary fundamental concepts, some unconventional aspects of the the physical chemistry of FWPE are discussed. These aspects are: (i) the extension of statistical mechanics techniques to include ionization equilibria and, in particular, the use of the recently proposed Site Binding-Rotational Isomeric State (SBRIS) model, which allows the calculation of ionization and conformational properties on the same foot; (ii) the recent progresses in the inclusion of proton equilibria in computer simulations; (iii) the possibility of mechanically induced CR in the stretching of FWPE; (iv) the non-trivial adsorption of FWPE on ionized surfaces with the same charge sign as the PE (the so-called "wrong side" of the isoelectric point); (v) the influence of macromolecular crowding on CR.
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Affiliation(s)
- Pablo M Blanco
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Claudio F Narambuena
- Grupo de Bionanotecnologia y Sistemas Complejos, Infap-CONICET & Facultad Regional San Rafael, Universidad Tecnológica Nacional, San Rafael 5600, Argentina
| | - Sergio Madurga
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Francesc Mas
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Josep L Garcés
- Chemistry Department, Technical School of Agricultural Engineering & AGROTECNIO, Lleida University (UdL), 25003 Lleida, Catalonia, Spain
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Kalipillai P, Raghuram E, Mani E. Effect of substrate charge density on the adsorption of intrinsically disordered protein amyloid β40: a molecular dynamics study. SOFT MATTER 2023; 19:1642-1652. [PMID: 36756755 DOI: 10.1039/d2sm01581a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The inhibitory effect of negatively charged gold nanoparticles (AuNPs) on amyloidogenic protein fibrillation has been established from experiments and computer simulations. Here, we investigate the effect of the charge density (σ) of gold (Au) surfaces on the adsorption of the intrinsically disordered amyloid β40 (Aβ40) monomer using molecular dynamics (MD) simulations. On the basis of the binding free energy, some key residues (ARG5, LYS16, LYS28, LEU17-ALA21, ILE31-VAL38) were found to be responsible for preventing the β-sheet formation, which is known to be a precursor for fibrillation. Until a critical charge density (σc) of -0.167 e nm-2, the key residues remained adsorbed on the Au slab. A saturation in the number of condensed counterions (Na+) on Aβ40 was also observed at σc. Beyond σc, the condensation of Na+ occurs only on the Au slab, leading to competition between positively charged key residues and condensed ions. This competition was found to be responsible for the lack of adsorption of the key residues, leading to β-sheet formation for σ > -0.167 e nm-2. This study suggests that if the key residues are not adsorbed, then β-sheet formation is observed, which can then lead to the development of proto-fibrils and subsequently fibrillation. Therefore the surface should have an optimal charge density to be an effective inhibitor of fibrillation.
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Affiliation(s)
- Pandurangan Kalipillai
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
- School of Chemical Engineering, Vellore Institute of Technology, Vellore, 632014, India
| | - E Raghuram
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
| | - Ethayaraja Mani
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
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Torres PB, Blanco PM, Garcés JL, Narambuena CF. The electrostatic potential inside and around α-lactalbumin: Fluctuations and mean-field models. J Chem Phys 2022; 157:205101. [DOI: 10.1063/5.0122275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The electrostatic potential (EP) generated by the protein α-lactoalbumin in the presence of added salt is computed as a thermal average at a given point in space. With this aim, constant pH Monte Carlo (MC) simulations are performed within the primitive model, namely, the solvent is treated as a continuum dielectric. The study of the thermal and spatial fluctuations of the EP reveals that they are remarkably high inside the protein. The calculations indicate that fluctuations inside the protein are mainly due to the asymmetric distribution of the charge groups, while the charge fluctuations of the titratable groups play a minor role. The computed EP matches very well with the one obtained from the Poisson equation for the average charge density in spherical symmetry. The Tanford–Kirkwood multipole expansion reproduces the simulated angular-averaged potential rather accurately. Surprisingly, two of the simplest mean-field models, the linear Poisson–Boltzmann (PB) equation and Donnan potential, provide good estimations of the average EP in the effective protein surface (surface EP). The linear PB equation predicts a linear relationship between charge and surface EP, which is numerically reproduced only if the small ions within the protein are taken into account. On the other hand, the partition coefficients of the small ions inside and outside the protein predicted by Donnan theory reproduce reasonably well the simulation results.
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Affiliation(s)
- Paola B. Torres
- Grupo Bionanotecnología y Sistemas Complejos. (UTN-CONICET), Facultad Regional San Rafael, Universidad Tecnológica Nacional, Av. General Urquiza 314 C.P, M5600 San Rafael, Mendoza, Argentina
| | - Pablo M. Blanco
- Materials Science and Physical Chemistry Department and Research Institute of Theoretical and Computational Chemistry (IQTCUB), University of Barcelona, 08028 Barcelona, Spain
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00 Prague 2, Czech Republic
| | - Josep L. Garcés
- Department of Chemistry, University of Lleida, Av. Alcalde Rovira Roure 191, E-25198 Lleida, Catalonia, Spain
| | - Claudio F. Narambuena
- Grupo Bionanotecnología y Sistemas Complejos. (UTN-CONICET), Facultad Regional San Rafael, Universidad Tecnológica Nacional, Av. General Urquiza 314 C.P, M5600 San Rafael, Mendoza, Argentina
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