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Gochev GG, Campbell RA, Schneck E, Zawala J, Warszynski P. Exploring proteins at soft interfaces and in thin liquid films - From classical methods to advanced applications of reflectometry. Adv Colloid Interface Sci 2024; 329:103187. [PMID: 38788307 DOI: 10.1016/j.cis.2024.103187] [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: 03/13/2024] [Revised: 05/12/2024] [Accepted: 05/12/2024] [Indexed: 05/26/2024]
Abstract
The history of the topic of proteins at soft interfaces dates back to the 19th century, and until the present day, it has continuously attracted great scientific interest. A multitude of experimental methods and theoretical approaches have been developed to serve the research progress in this large domain of colloid and interface science, including the area of soft colloids such as foams and emulsions. From classical methods like surface tension adsorption isotherms, surface pressure-area measurements for spread layers, and surface rheology probing the dynamics of adsorption, nowadays, advanced surface-sensitive techniques based on spectroscopy, microscopy, and the reflection of light, X-rays and neutrons at liquid/fluid interfaces offers important complementary sources of information. Apart from the fundamental characteristics of protein adsorption layers, i.e., surface tension and surface excess, the nanoscale structure of such layers and the interfacial protein conformations and morphologies are of pivotal importance for extending the depth of understanding on the topic. In this review article, we provide an extensive overview of the application of three methods, namely, ellipsometry, X-ray reflectometry and neutron reflectometry, for adsorption and structural studies on proteins at water/air and water/oil interfaces. The main attention is placed on the development of experimental approaches and on a discussion of the relevant achievements in terms of notable experimental results. We have attempted to cover the whole history of protein studies with these techniques, and thus, we believe the review should serve as a valuable reference to fuel ideas for a wide spectrum of researchers in different scientific fields where proteins at soft interface may be of relevance.
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Affiliation(s)
- Georgi G Gochev
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland; Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Richard A Campbell
- Division of Pharmacy and Optometry, University of Manchester, M13 9PT Manchester, UK
| | - Emanuel Schneck
- Physics Department, Technical University Darmstadt, 64289 Darmstadt, Germany
| | - Jan Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland
| | - Piotr Warszynski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland
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2
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Gochev GG, Schneck E, Miller R. Effects of Aqueous Isotopic Substitution on the Adsorption Dynamics and Dilational Rheology of β-Lactoglobulin Layers at the Water/Air Interface. J Phys Chem B 2024; 128:2821-2830. [PMID: 38471121 PMCID: PMC10961727 DOI: 10.1021/acs.jpcb.3c08417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 02/26/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024]
Abstract
The effect of the degree of isotopic substitution of the aqueous medium on the adsorption kinetics and the surface dilational rheological behavior at the water/air interface of the globular protein β-lactoglobulin was investigated. Aqueous solutions with fixed concentrations of 1 μM protein and 10 mM hydrogenous buffer with controlled pH 7 were prepared in H2O, D2O, and an isotopic mixture of 8.1% v/v D2O in H2O (called air contrast matched water, ACMW). Using a bubble shape analysis tensiometer, we obtained various experimental dependencies of the dilational viscoelasticity modulus E as a function of the dynamic surface pressure and of the frequency and amplitude of bubble surface area oscillations, either in the course of adsorption or after having reached a steady state. In general, the results revealed virtually no effect from substituting H2O by ACMW but distinct albeit relatively weak effects for intermediate adsorption times for D2O as the aqueous phase. In the final stage of adsorption, established after around 10 h, the equilibrium adsorption and the dilational rheological behavior of all protein layers under investigation are only very weakly affected by the presence of D2O. The obtained results help to design experimental protocols for protein adsorption studies, for example, by neutron reflectivity.
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Affiliation(s)
- Georgi G. Gochev
- Jerzy
Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland
- Institute
of Physical Chemistry, Bulgarian Academy
of Sciences, 1113 Sofia, Bulgaria
| | - Emanuel Schneck
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Reinhard Miller
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
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3
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Unfolded Lipase at Interfaces Studied via Interfacial Dilational Rheology: The Impact of Urea. COLLOIDS AND INTERFACES 2022. [DOI: 10.3390/colloids6040056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Unfolding can interrupt the activity of enzymes. Lipase, the enzyme responsible for triglyceride catalysis, can be deactivated by unfolding, which can significantly affect the yield of enzymatic processes in biochemical engineering. Different agents can induce lipase unfolding, among which we study the impact of urea as a strong denaturant. Unfolding weakens the rigidity and stability of globular proteins, thereby changing the viscoelastic properties of the protein adsorbed layers. These changes can be detected and quantified using interfacial dilational rheology. The urea-induced unfolding of lipase destructs its globular structure, making it more flexible. The interfacial tension and viscoelastic moduli of lipase adsorbed layers reduce upon the addition of urea in the range of studied concentrations. The results agree with the theory that, upon unfolding, a distal region of the loop and tail domain forms adjacent to the proximal region of the interface. The exchange of matter between these regions reduces the viscoelasticity of the unfolded lipase adsorbed layers. Additionally, unfolding reduces the rigidity and brittleness of the lipase adsorbed layers: the aged adsorbed layer of native lipase can break upon high-amplitude perturbations of the interfacial area, unlike the case for urea-induced unfolded lipase.
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Javadi A, Dowlati S, Shourni S, Miller R, Kraume M, Kopka K, Eckert K. Experimental techniques to study protein-surfactant interactions: New insights into competitive adsorptions via drop subphase and interface exchange. Adv Colloid Interface Sci 2022; 301:102601. [PMID: 35114446 DOI: 10.1016/j.cis.2022.102601] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/10/2022] [Indexed: 01/05/2023]
Abstract
Protein surfactant (PS) interactions is an essential topic for many fundamental and technological applications such as life science, nanobiotechnology processes, food industry, biodiesel production and drug delivery systems. Several experimental techniques and data analysis approaches have been developed to characterize PS interactions in bulk and at interfaces. However, to evaluate the mechanisms and the level of interactions quantitatively, e.g., PS ratio in complexes, their stability in bulk, and reversibility of their interfacial adsorption, new experimental techniques and protocols are still needed, especially with relevance for in-situ biological conditions. The available standard techniques can provide us with the basic understanding of interactions mainly under static conditions and far from physiological criteria. However, detailed measurements at complex interfaces can be formidable due to the sophisticated tools required to carefully probe nanometric phenomena at interfaces without disturbing the adsorbed layer. Tensiometry-based techniques such as drop profile analysis tensiometry (PAT) have been among the most powerful methods for characterizing protein's and surfactant's adsorption layers at interfaces via measuring equilibrium and dynamic interfacial tension and dilational rheology analysis. PAT provides us with insightful data such as kinetics and isotherms of adsorption and related surface activity parameters. However, the data analysis and interpretation can be challenging for mixed protein-surfactant solutions via standard PAT experimental protocols. The combination of a coaxial double capillary (micro flow exchange system) with drop profile analysis tensiometry (CDC-PAT) is a promising tool to provide valuable results under different competitive adsorption/desorption conditions via novel experimental protocols. CDC-PAT provides unique experimental protocols to exchange the droplet subphase in a continuous dynamic mode during the in-situ analysis of the corresponding interfacial adsorbed layer. The contribution of diffusion/convection mechanisms on the kinetics of the adsorption/desorption processes can also be investigated using CDC-PAT. Here, firstly, we review the commonly available techniques for characterizing protein-surfactant interactions in the bulk phase and at interfaces. Secondly, we give an overview for applications of the coaxial double capillary PAT setup for investigations of mixed protein-surfactant adsorbed layers and address recently developed protocols and analysis procedures. Exploring the competitive sequential adsorption of proteins and surfactants and the reversibility of pre-adsorbed layers via the subphase exchange are the particular experiments we can perform using CDC-PAT. Also the sequential and simultaneous competitive adsorption/desorption processes of some ionic and nonionic surfactants (SDS, CTAB, DTAB, and Triton) and proteins (bovine serum albumin (BSA), lysozyme, and lipase) using CDC-PAT are discussed. Last but not least, the fabrication of micro-nanocomposite layers and membranes are additional applications of CDC-PAT discussed in this work.
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Ramos J, Laux V, Haertlein M, Forsyth VT, Mossou E, Larsen S, Langkilde AE. The impact of folding modes and deuteration on the atomic resolution structure of hen egg-white lysozyme. Acta Crystallogr D Struct Biol 2021; 77:1579-1590. [PMID: 34866613 PMCID: PMC8647175 DOI: 10.1107/s2059798321010950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/20/2021] [Indexed: 11/10/2022] Open
Abstract
The biological function of a protein is intimately related to its structure and dynamics, which in turn are determined by the way in which it has been folded. In vitro refolding is commonly used for the recovery of recombinant proteins that are expressed in the form of inclusion bodies and is of central interest in terms of the folding pathways that occur in vivo. Here, biophysical data are reported for in vitro-refolded hydrogenated hen egg-white lysozyme, in combination with atomic resolution X-ray diffraction analyses, which allowed detailed comparisons with native hydrogenated and refolded perdeuterated lysozyme. Distinct folding modes are observed for the hydrogenated and perdeuterated refolded variants, which are determined by conformational changes to the backbone structure of the Lys97-Gly104 flexible loop. Surprisingly, the structure of the refolded perdeuterated protein is closer to that of native lysozyme than that of the refolded hydrogenated protein. These structural differences suggest that the observed decreases in thermal stability and enzymatic activity in the refolded perdeuterated and hydrogenated proteins are consequences of the macromolecular deuteration effect and of distinct folding dynamics, respectively. These results are discussed in the context of both in vitro and in vivo folding, as well as of lysozyme amyloidogenesis.
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Affiliation(s)
- Joao Ramos
- Life Sciences Group, Institute Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Valerie Laux
- Life Sciences Group, Institute Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Michael Haertlein
- Life Sciences Group, Institute Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
| | - V. Trevor Forsyth
- Life Sciences Group, Institute Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- Faculty of Natural Sciences, Keele University, Newcastle ST5 5BG, United Kingdom
- Faculty of Medicine, Lund University, 221 00 Lund, Sweden
- LINXS Institute for Advanced Neutron and X-ray Science, Scheelvagen 19, 223 70 Lund, Sweden
| | - Estelle Mossou
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Sine Larsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Annette E. Langkilde
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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DNA Interaction with a Polyelectrolyte Monolayer at Solution-Air Interface. Polymers (Basel) 2021; 13:polym13162820. [PMID: 34451359 PMCID: PMC8400178 DOI: 10.3390/polym13162820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 01/17/2023] Open
Abstract
The formation of ordered 2D nanostructures of double stranded DNA molecules at various interfaces attracts more and more focus in medical and engineering research, but the underlying intermolecular interactions still require elucidation. Recently, it has been revealed that mixtures of DNA with a series of hydrophobic cationic polyelectrolytes including poly(N,N-diallyl-N-hexyl-N-methylammonium) chloride (PDAHMAC) form a network of ribbonlike or threadlike aggregates at the solution—air interface. In the present work, we adopt a novel approach to confine the same polyelectrolyte at the solution—air interface by spreading it on a subphase with elevated ionic strength. A suite of techniques–rheology, microscopy, ellipsometry, and spectroscopy–are applied to gain insight into main steps of the adsorption layer formation, which results in non-monotonic kinetic dependencies of various surface properties. A long induction period of the kinetic dependencies after DNA is exposed to the surface film results only if the initial surface pressure corresponds to a quasiplateau region of the compression isotherm of a PDAHMAC monolayer. Despite the different aggregation mechanisms, the micromorphology of the mixed PDAHMAC/DNA does not depend noticeably on the initial surface pressure. The results provide new perspective on nanostructure formation involving nucleic acids building blocks.
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The dynamic surface properties of green fluorescent protein and its mixtures with poly(N,N-diallyl-N-hexyl-N-methylammonium chloride). J Taiwan Inst Chem Eng 2021. [DOI: 10.1016/j.jtice.2021.04.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Ramos J, Laux V, Haertlein M, Boeri Erba E, McAuley KE, Forsyth VT, Mossou E, Larsen S, Langkilde AE. Structural insights into protein folding, stability and activity using in vivo perdeuteration of hen egg-white lysozyme. IUCRJ 2021; 8:372-386. [PMID: 33953924 PMCID: PMC8086161 DOI: 10.1107/s2052252521001299] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
This structural and biophysical study exploited a method of perdeuterating hen egg-white lysozyme based on the expression of insoluble protein in Escherichia coli followed by in-column chemical refolding. This allowed detailed comparisons with perdeuterated lysozyme produced in the yeast Pichia pastoris, as well as with unlabelled lysozyme. Both perdeuterated variants exhibit reduced thermal stability and enzymatic activity in comparison with hydrogenated lysozyme. The thermal stability of refolded perdeuterated lysozyme is 4.9°C lower than that of the perdeuterated variant expressed and secreted in yeast and 6.8°C lower than that of the hydrogenated Gallus gallus protein. However, both perdeuterated variants exhibit a comparable activity. Atomic resolution X-ray crystallographic analyses show that the differences in thermal stability and enzymatic function are correlated with refolding and deuteration effects. The hydrogen/deuterium isotope effect causes a decrease in the stability and activity of the perdeuterated analogues; this is believed to occur through a combination of changes to hydrophobicity and protein dynamics. The lower level of thermal stability of the refolded perdeuterated lysozyme is caused by the unrestrained Asn103 peptide-plane flip during the unfolded state, leading to a significant increase in disorder of the Lys97-Gly104 region following subsequent refolding. An ancillary outcome of this study has been the development of an efficient and financially viable protocol that allows stable and active perdeuterated lysozyme to be more easily available for scientific applications.
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Affiliation(s)
- Joao Ramos
- Life Sciences Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Valerie Laux
- Life Sciences Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Michael Haertlein
- Life Sciences Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Elisabetta Boeri Erba
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- Institut de Biologie Structurale, Université de Grenoble Alpes, CEA, CNRS, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Katherine E. McAuley
- Diamond Light Source, Didcot OX11 0DE, United Kingdom
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - V. Trevor Forsyth
- Life Sciences Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- Faculty of Natural Sciences, Keele University, Newcastle-under-Lyme ST5 5BG, United Kingdom
| | - Estelle Mossou
- Life Sciences Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
- Partnership for Structural Biology (PSB), 71 Avenue des Martyrs, 38000 Grenoble, France
- Faculty of Natural Sciences, Keele University, Newcastle-under-Lyme ST5 5BG, United Kingdom
| | - Sine Larsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Annette E. Langkilde
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Krycki MM, Lin SY, Loglio G, Michailov AV, Miller R, Noskov BA. Impact of denaturing agents on surface properties of myoglobin solutions. Colloids Surf B Biointerfaces 2021; 202:111657. [PMID: 33684687 DOI: 10.1016/j.colsurfb.2021.111657] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 01/05/2023]
Abstract
The addition of denaturants strongly influences the surface properties of aqueous myoglobin solutions. The effect differs from the results for mixed solutions of the denaturants and other globular proteins, for example, bovine serum albumin (BSA), lysozyme and β-lactoglobulin (BLG), although the surface properties of the solutions of the pure proteins are similar. The kinetic dependencies of the dynamic surface elasticity of myoglobin solutions with guanidine hydrochloride (GuHCl) reveal at least two adsorption steps at denaturant concentrations higher than 1 M: a very fast increase of the dynamic surface elasticity to approximately 30 mN/m at the beginning of adsorption, and a slower growth to abnormally high values of 250-300 mN/m. At the same time, the surface elasticity of BSA/GuHCl, BLG/GuHCl and lysozyme/GuHCl solutions is a non-monotonic function of the surface age, and does not exceed 50 mN/m close to equilibrium. The high surface elasticity of myoglobin/GuHCl solutions may be associated with protein aggregation in the surface layer. The formation of aggregates is confirmed by ellipsometry and Brewster angle microscopy. The addition of ionic surfactants to protein solutions leads to the formation of myoglobin/surfactant complexes, and the kinetic dependencies of the dynamic surface elasticity display local maxima indicating multistep adsorption kinetics, unlike the corresponding results for solutions of other globular proteins mixed with ionic surfactants. Ellipsometry and infrared reflection-absorption spectroscopy allow tracing the adsorption of the complexes and their displacement from the interface at high surfactant concentrations.
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Affiliation(s)
- Michael M Krycki
- Department of Colloid Chemistry, St. Petersburg State University, Universitetsky pr. 26, St.-Petersburg, 198504, Russia; University of Opole, Opole, Poland
| | - Shi-Yow Lin
- National Taiwan University of Science and Technology, Chemical Engineering Department, Taipei, Taiwan
| | - Giuseppe Loglio
- Institute of Condensed Matter Chemistry and Technologies for Energy, Genoa, Italy
| | - Alexander V Michailov
- Department of Colloid Chemistry, St. Petersburg State University, Universitetsky pr. 26, St.-Petersburg, 198504, Russia
| | | | - Boris A Noskov
- Department of Colloid Chemistry, St. Petersburg State University, Universitetsky pr. 26, St.-Petersburg, 198504, Russia.
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Braun L, Kühnhammer M, von Klitzing R. Stability of aqueous foam films and foams containing polymers: Discrepancies between different length scales. Curr Opin Colloid Interface Sci 2020. [DOI: 10.1016/j.cocis.2020.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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11
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Alamdari S, Roeters SJ, Golbek TW, Schmüser L, Weidner T, Pfaendtner J. Orientation and Conformation of Proteins at the Air-Water Interface Determined from Integrative Molecular Dynamics Simulations and Sum Frequency Generation Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11855-11865. [PMID: 32921055 DOI: 10.1021/acs.langmuir.0c01881] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding the assembly of proteins at the air-water interface (AWI) informs the formation of protein films, emulsion properties, and protein aggregation. Determination of protein conformation and orientation at an interface is difficult to resolve with a single experimental or simulation technique alone. To date, the interfacial structure of even one of the most widely studied proteins, lysozyme, at the AWI remains unresolved. In this study, molecular dynamics (MD) simulations are used to determine if the protein adopts a side-on, head-on, or axial orientation at the AWI with two different forcefields, GROMOS-53a6 + SPC/E and a99SB-disp + TIP4P-D. Vibrational sum frequency generation (SFG) spectroscopy experiments and spectral SFG calculations validate consistency between the structure determined from MD and experiments. Overall, we show with strong agreement that lysozyme adopts an axial conformation at pH 7. Further, we provide molecular-level insight as to how pH influences the binding domains of lysozyme resulting in side-on adsorption near the isoelectric point of the lysozyme.
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Affiliation(s)
- Sarah Alamdari
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195-1750, United States
| | - Steven J Roeters
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Thaddeus W Golbek
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Lars Schmüser
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Jim Pfaendtner
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195-1750, United States
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12
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Structure of DPPC Monolayers at the Air/Buffer Interface: A Neutron Reflectometry and Ellipsometry Study. COATINGS 2020. [DOI: 10.3390/coatings10060507] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Langmuir monolayers of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine, known as DPPC, at the air/water interface are extensively used as model systems of biomembranes and pulmonary surfactant. The properties of these monolayers have been mainly investigated by surface pressure–area isotherms coupled with different complementary techniques such as Brewster angle microscopy, for example. Several attempts using neutron reflectometry (NR) or ellipsometry have also appeared in the literature. Here, we report structural information obtained by using NR and ellipsometry on DPPC monolayers in the liquid condensed phase. On one side, NR can resolve the thickness of the aliphatic tails and the degree of hydration of the polar headgroups. On the other side, ellipsometry gives information on the refractive index and, therefore, on the physical state of the monolayer. The thickness and surface excess obtained by multiple-angle-of-incidence ellipsometry (MAIE) is compared with the results from NR measurements yielding a good agreement. Besides, a novel approach is reported to calculate the optical anisotropy of the DPPC monolayer that depends on the orientation of the aliphatic chains. The results from both NR and ellipsometry are also discussed in the context of the existing results for DPPC monolayers at the air/water interface. The differences observed are rationalized by the presence of buffer molecules interacting with phospholipids.
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Akentiev AV, Gorniaia SB, Isakov NA, Lebedev VT, Milyaeva OY, Sedov VP, Semenov KN, Timoshen KA, Noskov BA. Surface properties of fullerenol C60(OH)20 solutions. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112904] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Gochev GG, Scoppola E, Campbell RA, Noskov BA, Miller R, Schneck E. β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 3. Neutron Reflectometry Study on the Effect of pH. J Phys Chem B 2019; 123:10877-10889. [PMID: 31725291 DOI: 10.1021/acs.jpcb.9b07733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Several characteristics of β-lactoglobulin (BLG) layers adsorbed at the air/water interface exhibit a strong pH dependence, but our knowledge on the underlying structure-property relations is still fragmental. Here, we therefore extend our recent studies by neutron reflectometry (NR) and provide a comprehensive overview through direct measurements of the surface excess Γ and the layers' molecular structure. This enables comparison with available literature data to draw general conclusions. The NR experiments were performed at various pH values and within a wide range of protein concentrations, CBLG. Adsorption kinetics measurements in air-contrast-matched-water and over a narrow Qz range enabled direct quantification of the dynamic surface excess Γ(t) and are found to be consistent with ellipsometry data. Near the isoelectric point, pI, the rates of adsorption and Γ are maximal but only at sufficiently high CBLG. NR data collected over a wider Qz range and in two aqueous isotopic contrasts revealed the structure of adsorbed BLG layers at a steady state close to equilibrium. Independent of the pH, BLG was found to form dense monolayers with average thicknesses of 1.1 nm, suggesting flattening of the BLG globules upon adsorption as compared with their bulk dimensions (≈3.5 nm). Near pI and at sufficiently high CBLG, a thick (≈5.5 nm) but looser secondary sublayer is additionally formed adjacent to the dense primary monolayer. The thickness of this sublayer can be interpreted in terms of disordered BLG dimers. The results obtained and notably the specific interfacial structuring of BLG near pI complement previous observations relating the impact of solution pH and CBLG on other interfacial characteristics such as surface pressure and surface dilational viscoelasticity modulus.
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Affiliation(s)
- Georgi G Gochev
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany.,Institute of Physical Chemistry , Bulgarian Academy of Sciences , 1113 Sofia , Bulgaria
| | - Ernesto Scoppola
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany
| | - Richard A Campbell
- Institut Laue-Langevin , 71 Avenue des Martyrs, CS20156 , 38042 Grenoble , France.,Division of Pharmacy and Optometry , University of Manchester , M13 9PT Manchester , U.K
| | - Boris A Noskov
- Institute of Chemistry , St. Petersburg State University , 198504 Saint-Petersburg , Russia
| | - Reinhard Miller
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany
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Hähl H, Griffo A, Safaridehkohneh N, Heppe J, Backes S, Lienemann M, Linder MB, Santen L, Laaksonen P, Jacobs K. Dynamic Assembly of Class II Hydrophobins from T. reesei at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:9202-9212. [PMID: 31268722 DOI: 10.1021/acs.langmuir.9b01078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Class II hydrophobins are amphiphilic proteins produced by filamentous fungi. One of their typical features is the tendency to accumulate at the interface between an aqueous phase and a hydrophobic phase, such as the air-water interface. The kinetics of the interfacial self-assembly of wild-type hydrophobins HFBI and HFBII and some of their engineered variants at the air-water interface were measured by monitoring the accumulated mass at the interface via nondestructive ellipsometry measurements. The resulting mass vs time curves revealed unusual kinetics for a monolayer formation that did not follow a typical Langmuir-type of behavior but had a rather coverage-independent rate instead. Typically, the full surface coverage was obtained at masses corresponding to a monolayer. The formation of multilayers was not observed. Atomic force microscopy revealed formation and growth of non-fusing protein clusters at the interface. The mechanism of the adsorption was studied by varying the structure or charges of the protein or the ionic strength of the subphase, revealing that the lateral interactions between the hydrophobins play a role in their interfacial assembly. Additionally, a theoretical model was introduced to identify the underlying mechanism of the unconventional adsorption kinetics.
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Affiliation(s)
| | - Alessandra Griffo
- Department of Bioproducts and Biosystems , Aalto University , P.O. Box 16100, FI-00076 Aalto , Finland
| | | | | | - Sebastian Backes
- Federal Institute for Material Research and Testing (BAM) , Unter den Eichen 87 , 12205 Berlin , Germany
| | - Michael Lienemann
- VTT Technical Research Centre of Finland Ltd. , Espoo 02150 , Finland
| | - Markus B Linder
- Department of Bioproducts and Biosystems , Aalto University , P.O. Box 16100, FI-00076 Aalto , Finland
| | | | - Päivi Laaksonen
- Department of Bioproducts and Biosystems , Aalto University , P.O. Box 16100, FI-00076 Aalto , Finland
- HAMK Tech, Häme University of Applied Sciences , P.O. Box 230, Hämeenlinna 13101 , Finland
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16
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Theodoratou A, Lee LT, Oberdisse J, Aubert-Pouëssel A. Equilibrium Protein Adsorption on Nanometric Vegetable Oil Hybrid Film/Water Interface Using Neutron Reflectometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6620-6629. [PMID: 31042395 DOI: 10.1021/acs.langmuir.9b00186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Nanofilms of about 2 nm thickness have been formed at the air-water interface using functionalized castor oil (ICO) with cross-linkable silylated groups. These hybrid films represent excellent candidates for replacing conventional polymeric materials in biomedical applications, but they need to be optimized in terms of biocompatibility, which is highly related to protein adsorption. Neutron reflectivity has been used to study the adsorption of two model proteins, bovine serum albumin and lysozyme, at the silylated oil (ICO)-water interface in the absence and presence of salt at physiologic ionic strength and pH and at different protein concentrations. These measurements are compared to adsorption at the air-water interface. While salt enhances adsorption by a similar degree at the air-water and oil-water interfaces, the impact of the oil film is significant with adsorption at the oil-water interface 3-4-fold higher compared to that at the air-water interface. Under these conditions, the concentration profiles of the adsorbed layers for both proteins indicate multilayer adsorption. The thickness of the outer layer (oil side) is close to the dimension of the minor axis of the protein molecule, ∼30 Å, suggesting a sideway orientation with the long axis parallel to the interface. The inner layer extends to 55-60 Å. Interestingly, in all cases, the composition of the oil film remains intact without significant protein penetration into the film. The optimal adsorption on these nanofilms, 1.7-2.0 mg·m-2, is comparable to the results obtained recently on thick solid cross-linked films using a quartz crystal microbalance and atomic force microscopy, showing in particular that adsorption at these ICO film interfaces under standard physiological conditions is nonspecific. These results furnish useful information toward the elaboration of vegetable oil-based nanofilms in direct nanoscale applications or as precursor films in the fabrication of thicker macroscopic films for biomedical applications.
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Affiliation(s)
- Antigoni Theodoratou
- Institut Charles Gerhardt Montpellier (ICGM), UMR5253 CNRS-UM-ENSCM , Place Eugène Bataillon , 34090 Montpellier , France
- European Institute of Membranes (IEM), UMR5635 CNRS-ESNCM , 300 Avenue du Professeur Emile Jeanbrau , 34090 Montpellier , France
| | - Lay-Theng Lee
- Laboratoire Léon Brillouin, CEA-CNRS, CEA Saclay, Université Paris-Saclay , 91191 Gif-sur-Yvette , France
| | - Julian Oberdisse
- Laboratoire Charles Coulomb (L2C), UMR5221 CNRS-UM , Place Eugène Bataillon , 34090 Montpellier , France
| | - Anne Aubert-Pouëssel
- Institut Charles Gerhardt Montpellier (ICGM), UMR5253 CNRS-UM-ENSCM , Place Eugène Bataillon , 34090 Montpellier , France
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17
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Milyaeva OY, Campbell RA, Gochev G, Loglio G, Lin SY, Miller R, Noskov BA. Dynamic Surface Properties of Mixed Dispersions of Silica Nanoparticles and Lysozyme. J Phys Chem B 2019; 123:4803-4812. [DOI: 10.1021/acs.jpcb.9b03352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Olga Yu. Milyaeva
- Department of Colloid Chemistry, St. Petersburg State University, Universitetsky pr. 26, 198504 St. Petersburg, Russia
| | - Richard A. Campbell
- Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, U.K
| | - Georgi Gochev
- Institute of Physical Chemistry, WWU Münster, 48149 Münster, Germany
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Giuseppe Loglio
- Institute of Condensed Matter Chemistry and Energy Technology, CNR-ICMATE, Genova, Italy
| | - Shi-Yow Lin
- Chemical Engineering Department, National Taiwan University of Science and Technology, Taipei 106, Taiwan
| | - Reinhard Miller
- Max-Planck-Institute for Colloid and Interface Science, D-14476 Golm, Germany
| | - Boris A. Noskov
- Department of Colloid Chemistry, St. Petersburg State University, Universitetsky pr. 26, 198504 St. Petersburg, Russia
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18
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Noskov BA, Timoshen KA, Akentiev AV, Chirkov NS, Dubovsky IM, Lebedev VT, Lin SY, Loglio G, Miller R, Sedov VP, Borisenkova AA. Dynamic Surface Properties of Fullerenol Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:3773-3779. [PMID: 30762366 DOI: 10.1021/acs.langmuir.8b04152] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Application of dilational surface rheology, surface tensiometry, ellipsometry, Brewster angle, and transmission electron and atomic force microscopies allowed the estimation of the structure of the adsorption layer of a fullerenol with a large number of hydroxyl groups, C60(OH) X ( X = 30 ± 2). The surface properties of fullerenol solutions proved to be similar to the properties of dispersions of solid nanoparticles and differ from those of the solutions of conventional surfactants and amphiphilic macromolecules. Although the surface activity of fullerenol is not high, it forms adsorption layers of high surface elasticity up to 170 mN/m. The layer consists of small interconnected surface aggregates with the thickness corresponding to two-three layers of fullerenol molecules. The aggregates are not adsorbed from the bulk phase but formed at the interface. The adsorption kinetics is controlled by an electrostatic adsorption barrier at the interface.
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Affiliation(s)
- Boris A Noskov
- St. Petersburg State University , 7/9 Universitetskaya nab. , St. Petersburg 199034 , Russia
| | - Kirill A Timoshen
- St. Petersburg State University , 7/9 Universitetskaya nab. , St. Petersburg 199034 , Russia
| | - Alexander V Akentiev
- St. Petersburg State University , 7/9 Universitetskaya nab. , St. Petersburg 199034 , Russia
| | - Nikolay S Chirkov
- St. Petersburg State University , 7/9 Universitetskaya nab. , St. Petersburg 199034 , Russia
| | - Ignat M Dubovsky
- B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC Kurchatov Institute , 188300 Gatchina, Leningrad , Russia
| | - Vasyli T Lebedev
- B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC Kurchatov Institute , 188300 Gatchina, Leningrad , Russia
| | - Shi-Yow Lin
- Chemical Engineering Department , National Taiwan University of Science and Technology , 43 Keelung Road, Section 4 , 106 Taipei , Taiwan
| | - Giuseppe Loglio
- Institute of Condensed Matter Chemistry and Technologies for Energy , 16149 Genoa , Italy
| | - Reinhard Miller
- MPI für Kolloid- und Grenzflächenforschung , Wissenschaftspark Golm, D-14424 Golm , Germany
| | - Victor P Sedov
- B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC Kurchatov Institute , 188300 Gatchina, Leningrad , Russia
| | - Alina A Borisenkova
- B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC Kurchatov Institute , 188300 Gatchina, Leningrad , Russia
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19
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Richert ME, García Rey N, Braunschweig B. Charge-Controlled Surface Properties of Native and Fluorophore-Labeled Bovine Serum Albumin at the Air-Water Interface. J Phys Chem B 2018; 122:10377-10383. [PMID: 30339752 PMCID: PMC6245422 DOI: 10.1021/acs.jpcb.8b06481] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
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Proteins
at interfaces are important for protein formulations and
in soft materials such as foam. Here, interfacial stability and physicochemical
properties are key elements, which drive macroscopic foam properties
through structure–property relations. Native and fluorescein
isothiocyanate-labeled bovine serum albumin (BSA) were used to modify
air–water interfaces as a function of pH. Characterizations
were performed with tensiometry and sum-frequency generation (SFG).
SFG spectra of O–H stretching vibrations reveal a phase reversal
and a pronounced minimum in O–H intensity at pH values of 5.3
and 4.7 for native and labeled BSA, respectively. This minimum is
attributed to the interfacial isoelectric point (IEP) and is accompanied
by a minimum in surface tension and negligible ζ-potentials
in the bulk. Interfacial proteins at pH values close to the IEP can
promote macroscopic foam stability and are predominately located in
the lamellae between individual gas bubbles as evidenced by confocal
fluorescence microscopy. Different from the classical stabilization
mechanisms, for example, via the electrostatic disjoining pressure,
we propose that the presence of more close-packed BSA, because of
negligible net charges, inside the foam lamellae is more effective
in reducing foam drainage as compared to a situation with strong repulsive
electrostatic interactions.
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Affiliation(s)
- Manuela E Richert
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany
| | - Natalia García Rey
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany.,Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , 48149 Münster , Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany.,Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , 48149 Münster , Germany
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20
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Campbell RA. Recent advances in resolving kinetic and dynamic processes at the air/water interface using specular neutron reflectometry. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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