1
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Lombardo Pontillo A, Ferrari M, Rospiccio M, Buffo A. Molecular Modeling of the Adsorption of an Egg Yolk Protein on a Water-Oil Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 38315870 DOI: 10.1021/acs.langmuir.3c03272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Egg yolk contains several molecular species with emulsifying properties, such as proteins and phospholipids. In particular, these molecules have both polar and nonpolar parts and thus can act as surfactants. One of the most surface-active proteins from egg yolk low-density lipoproteins is the so-called Apovitellenin-1. Experimental studies have been hindered by difficulties in isolating individual species from egg yolk lipoproteins. The purpose of this work was to assess the emulsifying properties of Apovitellenin-1 and any potential cooperative or competitive behavior in the presence of phospholipids. To do so, molecular simulations were carried out in a liquid-liquid interfacial system consisting of water and soybean oil, with varying concentrations of phospholipids and for different spatial configurations. To evaluate the conformational stability of the protein at the water-oil interface, the Gibbs free energy was computed from Metadynamics simulations as a function of the distance from the interface and of the radius of gyration. Moreover, a detailed analysis was also performed to determine which peptide residues were responsible for the protein adsorption at the oil-water interface as well as the lowering of the interfacial tension. Lastly, we combined the simulation results with a thermodynamic model to predict the interfacial tension behavior at increasing protein bulk concentration, which cannot be measured experimentally.
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Affiliation(s)
- Alessio Lombardo Pontillo
- Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
| | - Marco Ferrari
- Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
| | - Marcello Rospiccio
- Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
| | - Antonio Buffo
- Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
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2
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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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3
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Cathcarth M, Picco AS, Mondo GB, Cardoso MB, Longo GS. Competitive protein adsorption on charge regulating silica-like surfaces: the role of protonation equilibrium. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:364001. [PMID: 35366656 DOI: 10.1088/1361-648x/ac6388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 04/01/2022] [Indexed: 06/14/2023]
Abstract
We develop a molecular thermodynamic theory to study the interaction of some proteins with a charge regulating silica-like surface under a wide range of conditions, including pH, salt concentration and protein concentration. Proteins are modeled using their three dimensional structure from crystallographic data and the average experimental pKa of amino acid residues. As model systems, we study single-protein and binary solutions of cytochrome c, green fluorescent protein, lysozyme and myoglobin. Our results show that protonation equilibrium plays a critical role in the interactions of proteins with these type of surfaces. The terminal hydroxyl groups on the surface display considerable extent of charge regulation; protein residues with titratable side chains increase protonation according to changes in the local environment and the drop in pH near the surface. This behavior defines protein-surface interactions and leads to the emergence of several phenomena: (i) a complex non-ideal surface charge behavior; (ii) a non-monotonic adsorption of proteins as a function of pH; and (iii) the presence of two spatial regions, a protein-rich and a protein-depleted layer, that occur simultaneously at different distances from the surface when pH is slightly above the isoelectric point of the protein. In binary mixtures, protein adsorption and surface-protein interactions cannot be predicted from single-protein solution considerations.
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Affiliation(s)
- Marilina Cathcarth
- Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), UNLP-CONICET, La Plata, Argentina
| | - Agustin S Picco
- Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), UNLP-CONICET, La Plata, Argentina
| | - Gabriela B Mondo
- Brazilian Synchrotron (LNLS) and Brazilian Nanotechnology Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
- Institute of Chemistry (IQ), University of Campinas (UNICAMP), Campinas, Brazil
| | - Mateus B Cardoso
- Brazilian Synchrotron (LNLS) and Brazilian Nanotechnology Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
- Institute of Chemistry (IQ), University of Campinas (UNICAMP), Campinas, Brazil
| | - Gabriel S Longo
- Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), UNLP-CONICET, La Plata, Argentina
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4
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Caetano DLZ, Metzler R, Cherstvy AG, de Carvalho SJ. Adsorption of lysozyme into a charged confining pore. Phys Chem Chem Phys 2021; 23:27195-27206. [PMID: 34821240 DOI: 10.1039/d1cp03185f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Several applications arise from the confinement of proteins on surfaces because their stability and biological activity are enhanced. It is also known that the way in which a protein adsorbs on the surface is important for its biological function since its active sites should not be obstructed. In this study, the adsorption properties of hen egg-white lysozyme, HEWL, into a negatively charged silica pore is examined by employing a coarse-grained model and constant-pH Monte Carlo simulations. The role of electrostatic interactions is taken into account via including the Debye-Hückel potentials into the Cα structure-based model. We evaluate the effects of pH, salt concentration, and pore radius on the protein preferential orientation and spatial distribution of its residues regarding the pore surface. By mapping the residues that stay closer to the pore surface, we find that the increase of pH leads to orientational changes of the adsorbed protein when the solution pH gets closer to the HEWL isoelectric point. Under these conditions, the pKa shift of these important residues caused by the adsorption into the charged confining surface results in a HEWL charge distribution that stabilizes the adsorption in the observed protein orientation. We compare our observations to the results of the pKa shift for HEWL available in the literature and to some experimental data.
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Affiliation(s)
- Daniel L Z Caetano
- Institute of Chemistry, State University of Campinas (UNICAMP), Campinas, Brazil.,Center for Computational Engineering and Sciences, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Ralf Metzler
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Andrey G Cherstvy
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany.,Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Sidney J de Carvalho
- Department of Physics, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences, São José do Rio Preto, Brazil.
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5
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Kalipillai P, Mani E. Adsorption of the amyloid β40 monomer on charged gold nanoparticles and slabs: a molecular dynamics study. Phys Chem Chem Phys 2021; 23:18618-18627. [PMID: 34612399 DOI: 10.1039/d1cp01652k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Negatively charged nanoparticles are known to inhibit the fibrillation of amyloidogenic protein amyloid β (Aβ40), though the overall charge on the protein is negative. In this work a molecular dynamics study is reported to investigate the interaction of Aβ40 on negatively charged gold nanoparticles (3-5 nm) and charged (positive and negative) and neutral gold slabs. The equilibrium structures of Aβ40 on gold surfaces are characterized using residue-specific contacts on the gold surface, secondary structure analysis and binding free energy calculations. The simulation results reveal that the Aβ40 protein in water interconverts into β-sheets, which are building blocks of the mature fibrils, whereas on gold nanoparticles Aβ40 unfolds and adsorbs. Both the negatively charged gold nanoparticles and gold slabs arrest the formation of β-sheets in Aβ40, whereas the positively charged gold slab does not inhibit the formation of β-sheets. The residue-specific interactions between Aβ40 and the gold surfaces are important in governing the adsorption of Aβ40 on charged surfaces.
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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.
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6
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Watanabe G, Eimura H, Abbott NL, Kato T. Biomolecular Binding at Aqueous Interfaces of Langmuir Monolayers of Bioconjugated Amphiphilic Mesogenic Molecules: A Molecular Dynamics Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12281-12287. [PMID: 32970447 DOI: 10.1021/acs.langmuir.0c02191] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We report a molecular dynamics (MD) simulation study of protein binding at the aqueous-liquid crystal (LC) interfaces of bioconjugated mesogenic molecules. As a simple model of these interfaces, we use monolayers composed of biotin-conjugated or biotin-free amphiphilic mesogenic molecules and streptavidin in water. The all-atom MD simulations reveal that the binding of streptavidin to the biotin mesogenic monolayer is significantly stronger than that to biotin-free mesogenic monolayers. Although specific protein binding marginally increases the overall orientational order and the tilt of the biotin-conjugated mesogenic molecules of the monolayer, significant changes in tilt were observed near the bound protein (in contrast to the protein interaction with the monolayer without biotin). We also observe that specific protein binding changes the dynamic properties of the mesogens within the monolayer (e.g., lateral diffusion coefficients) and associated water. Overall, these MD simulations advance our understanding of the molecular-level phenomena involved in the binding of biomolecules and subsequent dynamic changes at the aqueous-LC interfaces. These results provide guidance to future molecular-level designs of biofunctional LC interfaces.
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Affiliation(s)
- Go Watanabe
- Department of Physics, School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0373, Japan
| | - Hiroki Eimura
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Nicholas L Abbott
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Takashi Kato
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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7
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Lecot S, Chevolot Y, Phaner-Goutorbe M, Yeromonahos C. Impact of Silane Monolayers on the Adsorption of Streptavidin on Silica and Its Subsequent Interactions with Biotin: Molecular Dynamics and Steered Molecular Dynamics Simulations. J Phys Chem B 2020; 124:6786-6796. [PMID: 32663028 DOI: 10.1021/acs.jpcb.0c04382] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein adsorption on surfaces is used in analytical tools as an immobilization mean to trap the analyte to be detected. However, protein adsorption can lead to a conformational change in the protein structure, resulting in a loss of bioactivity. Here, we study adsorption of a streptavidin-biotin complex on amorphous SiO2 surfaces functionalized with five different silane self-assembled monolayers by all-atom molecular dynamics simulations. We find that the streptavidin global conformational change, as well as the nature of residues with high mobility, depends on the alkyl chain length and head-group charge of silane molecules. Effects on interactions with biotin are further investigated by steered molecular dynamics (SMD) simulations, which mimics atomic force microscopy (AFM) with the biotin attached on the tip. We show the combined effects of adsorption-induced global conformational changes and of the position of residues with high mobility on the streptavidin-biotin rupture force. By comparing our results to experimental and SMD rupture forces obtained in water, without any surface, we conclude that silane with uncharged and short alkyl chains allows streptavidin immobilization, while keeping biotin interactions better than silanes with long alkyl chains or charged head groups.
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Affiliation(s)
- Solène Lecot
- Université de Lyon, Institut des Nanotechnologies de Lyon UMR 5270, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France
| | - Yann Chevolot
- Université de Lyon, Institut des Nanotechnologies de Lyon UMR 5270, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France
| | - Magali Phaner-Goutorbe
- Université de Lyon, Institut des Nanotechnologies de Lyon UMR 5270, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France
| | - Christelle Yeromonahos
- Université de Lyon, Institut des Nanotechnologies de Lyon UMR 5270, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France
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8
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Swiatek S, Komorek P, Jachimska B. Adsorption of β-lactoglobulin A on gold surface determined in situ by QCM-D measurements. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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9
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Protein-surface interactions at the nanoscale: Atomistic simulations with implicit solvent models. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2018.11.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Mathematical modeling approaches to describe the dynamics of protein adsorption at solid interfaces. Colloids Surf B Biointerfaces 2018; 162:370-379. [DOI: 10.1016/j.colsurfb.2017.12.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/21/2017] [Accepted: 12/06/2017] [Indexed: 11/22/2022]
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11
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Pérez-Fuentes L, Drummond C, Faraudo J, Bastos-González D. Adsorption of Milk Proteins (β-Casein and β-Lactoglobulin) and BSA onto Hydrophobic Surfaces. MATERIALS (BASEL, SWITZERLAND) 2017; 10:E893. [PMID: 28767100 PMCID: PMC5578259 DOI: 10.3390/ma10080893] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 06/30/2017] [Accepted: 07/24/2017] [Indexed: 12/22/2022]
Abstract
Here, we study films of proteins over planar surfaces and protein-coated microspheres obtained from the adsorption of three different proteins ( β -casein, β -lactoglobulin and bovine serum albumin (BSA)). The investigation of protein films in planar surfaces is performed by combining quartz crystal microbalance (QCM) and atomic force microscopy (AFM) measurements with all-atomic molecular dynamics (MD) simulations. We found that BSA and β -lactoglobulin form compact monolayers, almost without interstices between the proteins. However, β -casein adsorbs forming multilayers. The study of the electrokinetic mobility of protein-coated latex microspheres shows substantial condensation of ions from the buffer over the complexes, as predicted from ion condensation theories. The electrokinetic behavior of the latex-protein complexes is dominated by the charge of the proteins and the phenomenon of ion condensation, whereas the charge of the latex colloids plays only a minor role.
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Affiliation(s)
- Leonor Pérez-Fuentes
- Biocolloid and Fluid Physics Group, Department of Applied Physics, University of Granada, Av. Fuentenueva 2, E-18001 Granada, Spain.
| | - Carlos Drummond
- CNRS, Centre de Recherche Paul Pascal (CRPP), UPR 8641, F3300 Pessac, France.
- Université de Bordeaux, CRPP, UPR 8641, F-33600 Pessac, France.
| | - Jordi Faraudo
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, E-08193 Bellaterra, Barcelona, Spain.
| | - Delfi Bastos-González
- Biocolloid and Fluid Physics Group, Department of Applied Physics, University of Granada, Av. Fuentenueva 2, E-18001 Granada, Spain.
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12
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Abstract
Understanding protein-inorganic surface interactions is central to the rational design of new tools in biomaterial sciences, nanobiotechnology and nanomedicine. Although a significant amount of experimental research on protein adsorption onto solid substrates has been reported, many aspects of the recognition and interaction mechanisms of biomolecules and inorganic surfaces are still unclear. Theoretical modeling and simulations provide complementary approaches for experimental studies, and they have been applied for exploring protein-surface binding mechanisms, the determinants of binding specificity towards different surfaces, as well as the thermodynamics and kinetics of adsorption. Although the general computational approaches employed to study the dynamics of proteins and materials are similar, the models and force-fields (FFs) used for describing the physical properties and interactions of material surfaces and biological molecules differ. In particular, FF and water models designed for use in biomolecular simulations are often not directly transferable to surface simulations and vice versa. The adsorption events span a wide range of time- and length-scales that vary from nanoseconds to days, and from nanometers to micrometers, respectively, rendering the use of multi-scale approaches unavoidable. Further, changes in the atomic structure of material surfaces that can lead to surface reconstruction, and in the structure of proteins that can result in complete denaturation of the adsorbed molecules, can create many intermediate structural and energetic states that complicate sampling. In this review, we address the challenges posed to theoretical and computational methods in achieving accurate descriptions of the physical, chemical and mechanical properties of protein-surface systems. In this context, we discuss the applicability of different modeling and simulation techniques ranging from quantum mechanics through all-atom molecular mechanics to coarse-grained approaches. We examine uses of different sampling methods, as well as free energy calculations. Furthermore, we review computational studies of protein-surface interactions and discuss the successes and limitations of current approaches.
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13
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Ramakrishnan SK, Zhu J, Gergely C. Organic-inorganic interface simulation for new material discoveries. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2016. [DOI: 10.1002/wcms.1277] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sathish Kumar Ramakrishnan
- Nanobiology Institute; Yale University; West Haven CT USA
- Laboratoire Charles Coulomb (L2C); UMR 5221 CNRS-Université de Montpellier; Montpellier France
| | - Jie Zhu
- Nanobiology Institute; Yale University; West Haven CT USA
| | - Csilla Gergely
- Laboratoire Charles Coulomb (L2C); UMR 5221 CNRS-Université de Montpellier; Montpellier France
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14
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Zare D, Allison JR, McGrath KM. Molecular Dynamics Simulation of β-Lactoglobulin at Different Oil/Water Interfaces. Biomacromolecules 2016; 17:1572-81. [DOI: 10.1021/acs.biomac.5b01709] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Davoud Zare
- MacDiarmid
Institute for Advanced Materials and Nanotechnology, School of Chemical
and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
- Riddet
Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
| | - Jane R. Allison
- Centre
for Theoretical Chemistry and Physics, Institute of Natural and Mathematical
Sciences, Massey University Auckland (Oteha Rohe), Albany Highway, Albany 0632, New Zealand
- Biomolecular
Interaction Centre, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1023, New Zealand
| | - Kathryn M. McGrath
- MacDiarmid
Institute for Advanced Materials and Nanotechnology, School of Chemical
and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
- Riddet
Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
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15
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Zare D, McGrath KM, Allison JR. Deciphering β-Lactoglobulin Interactions at an Oil-Water Interface: A Molecular Dynamics Study. Biomacromolecules 2015; 16:1855-61. [PMID: 25989152 DOI: 10.1021/acs.biomac.5b00467] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein adsorption at liquid-liquid interfaces is of immense relevance to many biological processes and dairy-based functional foods. Due to experimental limitations, however, there is still a remarkable lack of understanding of the adsorption mechanism, particularly at a molecular level. In this study, atomistic molecular dynamics simulations were used to elucidate the approach and adsorption mechanism of β-lactoglobulin (β-LG) at a decane-water interface. Through multiple independent simulations starting from three representative initial orientations of β-LG relative to the decane surface the rate at which β-LG approaches the oil/water interface is found to be independent of its initial orientation, and largely stochastic in nature. While the residues that first make contact with the decane and the final orientation of β-LG upon adsorption are similar in all cases, the adsorption process is driven predominantly by structural rearrangements that preserve the secondary structure but expose hydrophobic residues to the decane surface. This detailed characterization of the adsorption of β-LG at an oil/water interface should inform the design and development of novel encapsulation and delivery systems in the food and pharmaceutical sciences.
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Affiliation(s)
- Davoud Zare
- †MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.,‡Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
| | - Kathryn M McGrath
- †MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.,‡Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
| | - Jane R Allison
- §Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey University Auckland, Albany, Auckland 0632, New Zealand.,∥Biomolecular Interaction Centre, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.,⊥Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland, New Zealand
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16
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Schuster E, Hermansson AM, Ohgren C, Rudemo M, Lorén N. Interactions and diffusion in fine-stranded β-lactoglobulin gels determined via FRAP and binding. Biophys J 2014; 106:253-62. [PMID: 24411257 DOI: 10.1016/j.bpj.2013.11.2959] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 10/31/2013] [Accepted: 11/14/2013] [Indexed: 11/28/2022] Open
Abstract
The effects of electrostatic interactions and obstruction by the microstructure on probe diffusion were determined in positively charged hydrogels. Probe diffusion in fine-stranded gels and solutions of β-lactoglobulin at pH 3.5 was determined using fluorescence recovery after photobleaching (FRAP) and binding, which is widely used in biophysics. The microstructures of the β-lactoglobulin gels were characterized using transmission electron microscopy. The effects of probe size and charge (negatively charged Na2-fluorescein (376Da) and weakly anionic 70kDa FITC-dextran), probe concentration (50 to 200 ppm), and β-lactoglobulin concentration (9% to 12% w/w) on the diffusion properties and the electrostatic interaction between the negatively charged probes and the positively charged gels or solutions were evaluated. The results show that the diffusion of negatively charged Na2-fluorescein is strongly influenced by electrostatic interactions in the positively charged β-lactoglobulin systems. A linear relationship between the pseudo-on binding rate constant and the β-lactoglobulin concentration for three different probe concentrations was found. This validates an important assumption of existing biophysical FRAP and binding models, namely that the pseudo-on binding rate constant equals the product of the molecular binding rate constant and the concentration of the free binding sites. Indicators were established to clarify whether FRAP data should be analyzed using a binding-diffusion model or an obstruction-diffusion model.
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Affiliation(s)
- Erich Schuster
- Department of Structure and Material Design, Swedish Institute for Food and Biotechnology, SIK, Göteborg, Sweden; SuMo BIOMATERIALS, VINN Excellence Center, Chalmers University of Technology, Göteborg, Sweden
| | - Anne-Marie Hermansson
- Department of Structure and Material Design, Swedish Institute for Food and Biotechnology, SIK, Göteborg, Sweden; SuMo BIOMATERIALS, VINN Excellence Center, Chalmers University of Technology, Göteborg, Sweden; Department of Applied Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden
| | - Camilla Ohgren
- Department of Structure and Material Design, Swedish Institute for Food and Biotechnology, SIK, Göteborg, Sweden; SuMo BIOMATERIALS, VINN Excellence Center, Chalmers University of Technology, Göteborg, Sweden
| | - Mats Rudemo
- SuMo BIOMATERIALS, VINN Excellence Center, Chalmers University of Technology, Göteborg, Sweden; Mathematical Sciences, Chalmers University of Technology, and the University of Gothenburg, Göteborg, Sweden
| | - Niklas Lorén
- Department of Structure and Material Design, Swedish Institute for Food and Biotechnology, SIK, Göteborg, Sweden; SuMo BIOMATERIALS, VINN Excellence Center, Chalmers University of Technology, Göteborg, Sweden.
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17
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Liu J, Liao C, Zhou J. Multiscale simulations of protein G B1 adsorbed on charged self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11366-11374. [PMID: 23947739 DOI: 10.1021/la401171v] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The orientation of an antibody plays an important role in the development of immunosensors. Protein G is an antibody binding protein, which specifically targets the Fc fragment of an antibody. In this work, the orientation of prototypical and mutated protein G B1 adsorbed on positively and negatively charged self-assembled monolayers was studied by parallel tempering Monte Carlo and all-atom molecular dynamics simulations. Both methods present generally similar orientation distributions of protein G B1 for each kind of surface. The root-mean-square deviation, DSSP, gyration radius, eccentricity, dipole moment, and superimposed structures of protein G B1 were analyzed. Moreover, the orientation of binding antibody was also predicted in this work. Simulation results show that with the same orientation trends, the mutant exhibits narrower orientation distributions than does the prototype, which was mainly caused by the stronger dipole of the mutant. Both kinds of proteins adsorbed on charged surfaces were induced by the competition of electrostatic interaction and vdW interaction; the electrostatic interaction energy dominated the adsorption behavior. The protein adsorption was also largely affected by the distribution of charged residues within the proteins. Thus, the prototype could adsorb on a negatively charged surface, although it keeps a net charge of -4 e. The mutant has imperfect opposite orientation when it adsorbed on oppositely charged surfaces. For the mutant on a carboxyl-functionalized self-assembled monolayer (COOH-SAM), the orientation was the same as that inferred by experiments. While for the mutant on amine-functionalized self-assembled monolayer (NH2-SAM), the orientation was induced by the competition between attractive interactions (led by ASP40 and GLU56) and repulsive interactions (led by LYS10); thus, the perfect opposite orientation could not be obtained. On both surfaces, the adsorbed protein could retain its native conformation. The desired orientation of protein G B1, which would increase the efficiency of binding antibodies, could be obtained on a negatively charged surface adsorbed with the prototype. Further, we deduced that with the packing density of 12,076 protein G B1 domain per μm(2), the efficiency of the binding IgG would be maximized. The simulation results could be applied to control the orientation of protein G B1 in experiments and to provide a better understanding to maximize the efficiency of antibody binding.
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Affiliation(s)
- Jie Liu
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology , Guangzhou, Guangdong, 510640, People's Republic of China
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Tong C. The numerical study of the adsorption of flexible polyelectrolytes with the annealed charge distribution onto an oppositely charged sphere by the self-consistent field theory. J Chem Phys 2013; 139:084903. [DOI: 10.1063/1.4819037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Costa D, Garrain PA, Baaden M. Understanding small biomolecule-biomaterial interactions: A review of fundamental theoretical and experimental approaches for biomolecule interactions with inorganic surfaces. J Biomed Mater Res A 2012; 101:1210-22. [DOI: 10.1002/jbm.a.34416] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/07/2012] [Accepted: 08/12/2012] [Indexed: 12/13/2022]
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Panos M, Sen TZ, Ahunbay MG. Molecular simulation of fibronectin adsorption onto polyurethane surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:12619-12628. [PMID: 22856639 DOI: 10.1021/la301546v] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Poly(ethylene glycol)-based polyurethanes have been widely used in biomedical applications; however, they are prone to swelling. A natural polyol, castor oil, can be incorporated into these polyurethanes to control the degree of the swelling, which alters mechanical properties and protein adsorption characteristic of the polymers. In this work, we modeled poly(ethylene glycol) and castor oil copolymers of hexamethylene diisocyanate-based polyurethanes (PEG-HDI and CO-HDI, respectively) and compared their mechanisms for fibronectin adsorption using molecular mechanics and molecular dynamics simulations. Results showed that the interplay between the hydrophobic residues concentrated at the N-terminal end of the protein, the surface roughness, and the hydrophilicity of the polymer surface determine the overall protein adsorption affinity. Incorporating explicit water molecules in the simulations results in higher affinity for fibronectin adsorption to more hydrophobic surface of CO-HDI surfaces, emphasizing the role that water molecules play during adsorption. We also observed that the strain energies that are indicative of flexibility and consequently entropy are significantly affected by the changes in the patterns of β-sheet formation/breaking. Our study lends supports to the view that while castor oil controls the degree of swelling, it increases the adsorption of fibronectin to a limited extent due to the interplay between its hydrophobicity and its surface roughness, which needs to be taken into account during the design of polyurethane-based biomaterials.
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Affiliation(s)
- Melisa Panos
- Department of Chemical Engineering, Istanbul Technical University, Istanbul, Turkey
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Lu F, Zhang S, Gao H, Jia H, Zheng L. Protein-decorated reduced oxide graphene composite and its application to SERS. ACS APPLIED MATERIALS & INTERFACES 2012; 4:3278-3284. [PMID: 22692825 DOI: 10.1021/am300634n] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A globular protein, β-lactoglobulin (BLG), was used to decorate reduced graphene oxide sheets (RGO) and the obtained BLG-RGO composite can be dispersed in aqueous solution with pH-sensitive solubility. The morphology of the BLG-RGO composite was studied by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results indicate that BLG-RGO is effectively exfoliated with an average thickness of 2.5 nm. UV-vis spectra were performed to examine the reduction degree and determine the optimum concentration of β-lactoglobulin and appropriate pH value. Furthermore, Raman spectra demonstrate that β-Lactoglobulin promotes the chemical reduction process of graphene oxide and benefits to repair the crystal defects. Due to the adsorption of β-Lactoglobulin on the surface of graphene sheets, the BLG-RGO composite was further used as template for Au nanoparticles assembly. These Au nanoparticles assembled on the BLG-RGO composite were shown to yield a large SERS enhancement for Rhodamine 6G.
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Affiliation(s)
- Fei Lu
- Key Laboratory of Colloid and Interface Chemistry, Shandong University , Ministry of Education, Jinan, 250100, P. R. China
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Zhai J, Wooster TJ, Hoffmann SV, Lee TH, Augustin MA, Aguilar MI. Structural rearrangement of β-lactoglobulin at different oil-water interfaces and its effect on emulsion stability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:9227-9236. [PMID: 21668007 DOI: 10.1021/la201483y] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Understanding the factors that control protein structure and stability at the oil-water interface continues to be a major focus to optimize the formulation of protein-stabilized emulsions. In this study, a combination of synchrotron radiation circular dichroism spectroscopy, front-face fluorescence spectroscopy, and dual polarization interferometry (DPI) was used to characterize the conformation and geometric structure of β-lactoglobulin (β-Lg) upon adsorption to two oil-water interfaces: a hexadecane-water interface and a tricaprylin-water interface. The results show that, upon adsorption to both oil-water interfaces, β-Lg went through a β-sheet to α-helix transition with a corresponding loss of its globular tertiary structure. The degree of conformational change was also a function of the oil phase polarity. The hexadecane oil induced a much higher degree of non-native α-helix compared to the tricaprylin oil. In contrast to the β-Lg conformation in solution, the non-native α-helical-rich conformation of β-Lg at the interface was resistant to further conformational change upon heating. DPI measurements suggest that β-Lg formed a thin dense layer at emulsion droplet surfaces. The effects of high temperature and the presence of salt on these β-Lg emulsions were then investigated by monitoring changes in the ζ-potential and particle size. In the absence of salt, high electrostatic repulsion meant β-Lg-stabilized emulsions were resistant to heating to 90 °C. Adding salt (120 mM NaCl) before or after heating led to emulsion flocculation due to the screening of the electrostatic repulsion between colloidal particles. This study has provided insight into the structural properties of proteins adsorbed at the oil-water interface and has implications in the formulation and production of emulsions stabilized by globular proteins.
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Affiliation(s)
- Jiali Zhai
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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Neogi P, Wang JC. Stability of two-dimensional growth of a packed body of proteins on a solid surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5347-5353. [PMID: 21473573 DOI: 10.1021/la104616b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Adsorption of proteins from the bulk is at times accompanied by a rearrangement which leads to the formation of closed packed bodies, that may or may not be crystalline. Mass transfer of protein molecules on a surface is modeled. Forced diffusion by van der Waals and electrostatic forces leads to segregation, which is eventually a different phase that is assumed to be thermodynamically favored. The net effective force in two-dimensions has been modeled approximately and shown to be much stronger and more long ranged than in the bulk: that is, under the same conditions, the protein molecules may not aggregate in the bulk they may aggregate on a surface. These forces have been used only indirectly but equivalently as an adsorption-desorption step at the interline. Eventually, a linear stability analysis of the growing body shows it to be unstable and would give rise to whiskers that are one molecule thick. This is what is observed experimentally. The conditions that give rise to the instability have been determined. The reverse case of rinsing of the protein molecules has also been studied experimentally and has been analyzed using the same mechanisms. Here it is seen that thicker inroads into the packed body cause the interline to take on a spongy appearance. It is conjectured that eventually islands will appear as seen in the experiments.
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Affiliation(s)
- P Neogi
- Chemical and Biological Engineering Department, Missouri University of Science and Technology, Rolla, Missouri 65409-1230, United States.
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Understanding protein adsorption phenomena at solid surfaces. Adv Colloid Interface Sci 2011; 162:87-106. [PMID: 21295764 DOI: 10.1016/j.cis.2010.12.007] [Citation(s) in RCA: 986] [Impact Index Per Article: 75.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 12/21/2010] [Accepted: 12/28/2010] [Indexed: 11/21/2022]
Abstract
Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to explain the frequently observed phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into mathematical concepts and model descriptions. Relevant experimental and computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined.
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Tosaka R, Yamamoto H, Ohdomari I, Watanabe T. Adsorption mechanism of ribosomal protein L2 onto a silica surface: a molecular dynamics simulation study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9950-9955. [PMID: 20429542 DOI: 10.1021/la1004352] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A large-scale molecular dynamics simulation was carried out in order to investigate the adsorption mechanism of ribosomal protein L2 (RPL2) onto a silica surface at various pH values. RPL2 is a constituent protein of the 50S large ribosomal subunit, and a recent experimental report showed that it adsorbs strongly to silica surfaces and that it can be used to immobilize proteins on silica surfaces. The simulation results show that RPL2, especially domains 1 (residues 1-60) and 3 (residues 203-273), adsorbed more tightly to the silica surface above pH 7. We found that a major driving force for the adsorption of RPL2 onto the silica surface is the electrostatic interaction and that the structural flexibility of domains 1 and 3 may further contribute to the high affinity.
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Affiliation(s)
- Ryo Tosaka
- Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan.
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Rabe M, Verdes D, Seeger S. Understanding Cooperative Protein Adsorption Events at the Microscopic Scale: A Comparison between Experimental Data and Monte Carlo Simulations. J Phys Chem B 2010; 114:5862-9. [DOI: 10.1021/jp909601m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Rabe
- Institute of Physical Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Dorinel Verdes
- Institute of Physical Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Stefan Seeger
- Institute of Physical Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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