1
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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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Zheng X, Ni Z, Pei Q, Wang M, Tan J, Bai S, Shi F, Ye S. Probing the Molecular Structure and Dynamics of Membrane-Bound Proteins during Misfolding Processes by Sum-Frequency Generation Vibrational Spectroscopy. Chempluschem 2024; 89:e202300684. [PMID: 38380553 DOI: 10.1002/cplu.202300684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 02/22/2024]
Abstract
Protein misfolding and amyloid formation are implicated in the protein dysfunction, but the underlying mechanism remains to be clarified due to the lack of effective tools for detecting the transient intermediates. Sum frequency generation vibrational spectroscopy (SFG-VS) has emerged as a powerful tool for identifying the structure and dynamics of proteins at the interfaces. In this review, we summarize recent SFG-VS studies on the structure and dynamics of membrane-bound proteins during misfolding processes. This paper first introduces the methods for determining the secondary structure of interfacial proteins: combining chiral and achiral spectra of amide A and amide I bands and combining amide I, amide II, and amide III spectral features. To demonstrate the ability of SFG-VS in investigating the interfacial protein misfolding and amyloid formation, studies on the interactions between different peptides/proteins (islet amyloid polypeptide, amyloid β, prion protein, fused in sarcoma protein, hen egg-white lysozyme, fusing fusion peptide, class I hydrophobin SC3 and class II hydrophobin HFBI) and surfaces such as lipid membranes are discussed. These molecular-level studies revealed that SFG-VS can provide a unique understanding of the mechanism of interfacial protein misfolding and amyloid formation in real time, in situ and without any exogenous labeling.
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Affiliation(s)
- Xiaoxuan Zheng
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Zijian Ni
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Quanbing Pei
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Mengmeng Wang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Junjun Tan
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Shiyu Bai
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Fangwen Shi
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Shuji Ye
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
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3
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Tan J, Wang M, Ni Z, Pei R, Shi F, Ye S. Intermolecular Protein-Water Coupling Impedes the Coupling Between the Amide A and Amide I Mode in Interfacial Proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:6587-6594. [PMID: 38486393 DOI: 10.1021/acs.langmuir.4c00246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
The coupling between different vibrational modes in proteins is essential for chemical dynamics and biological functions and is linked to the propagation of conformational changes and pathways of allosteric communication. However, little is known about the influence of intermolecular protein-H2O coupling on the vibrational coupling between amide A (NH) and amide I (C═O) bands. Here, we investigate the NH/CO coupling strength in various peptides with different secondary structures at the lipid cell membrane/H2O interface using femtosecond time-resolved sum frequency generation vibrational spectroscopy (SFG-VS) in which a femtosecond infrared pump is used to excite the amide A band, and SFG-VS is used to probe transient spectral evolution in the amide A and amide I bands. Our results reveal that the NH/CO coupling strength strongly depends on the bandwidth of the amide I mode and the coupling of proteins with water molecules. A large extent of protein-water coupling significantly reduces the delocalization of the amide I mode along the peptide chain and impedes the NH/CO coupling strength. A large NH/CO coupling strength is found to show a strong correlation with the high energy transfer rate found in the light-harvesting proteins of green sulfur bacteria, which may understand the mechanism of energy transfer through a molecular system and assist in controlling vibrational energy transfer by engineering the molecular structures to achieve high energy transfer efficiency.
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Affiliation(s)
- Junjun Tan
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Mengmeng Wang
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Zijian Ni
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Ruoqi Pei
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Fangwen Shi
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Shuji Ye
- Hefei National Research Center for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
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4
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Phan CM. Affinity of Amphiphilic Molecules to Air/Water Surface. ACS OMEGA 2023; 8:47928-47937. [PMID: 38144045 PMCID: PMC10733914 DOI: 10.1021/acsomega.3c06512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/21/2023] [Accepted: 11/24/2023] [Indexed: 12/26/2023]
Abstract
The affinity of amphiphiles to the water/air surface was modeled by adapting Eberhart's equation. The proposed method successfully describes surface tension for all amphiphilic structures, including alkanols, carboxylic acids, nonionic, ionic, and Gemini surfactants. The model is more effective than conventional analysis for amphiphiles with multiple ionic states. The prediction was consistently validated at different temperatures and nonaqueous solvents. The modeling results show a linear correlation between surface affinity and hydrophobicity/hydrophilicity. For alkanols, the affinity increment is 2.84 kJ/mol per CH2 group, the same as the reported hydrophobic energy from monomer to aggregate for nonionic surfactants. For carboxylic acids, the affinity increment per CH2 group is 3.18 kJ/mol, incorporating the degree of acid dissociation. The affinity-hydrophilicity correlation is approximately -0.22 kJ/mol per oxyethylene group. The affinity constant can be obtained for all classes of amphiphiles to clarify the relationship between the molecular structure and surface activity.
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Affiliation(s)
- Chi Minh Phan
- Discipline of Chemical Engineering,
WASM:MECE, Curtin University, Perth, Western Australia 6845, Australia
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5
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Leister N, Götz V, Jan Bachmann S, Nachtigall S, Hosseinpour S, Peukert W, Karbstein H. A comprehensive methodology to study double emulsion stability. J Colloid Interface Sci 2023; 630:534-548. [DOI: 10.1016/j.jcis.2022.10.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/15/2022] [Accepted: 10/22/2022] [Indexed: 11/05/2022]
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Kaur H, Verma M, Kaur S, Rana B, Singh N, Jena KC. Elucidating the Molecular Structure of Hydrophobically Modified Polyethylenimine Nanoparticles and Its Potential Implications for DNA Binding. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:13456-13468. [PMID: 36279506 DOI: 10.1021/acs.langmuir.2c01912] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The structural properties of the polyethylenimine (PEI) polymer are generally tuned and selectively modified to reinforce its potential in a broad spectrum of applied domains of medicine, healthcare, material design, sensing, and electronic optimization. The selective modification of the polymer brings about changes in its interfacial characteristics and behavior. The current work involves the synthesis of naphthalimide conjugated polyethylenimine organic nanoparticles (NPEI-ONPs). The interfacial molecular structure of NPEI-ONPs is explored in an aqueous medium at pH 7.4 using surface tensiometry and sum-frequency generation vibrational spectroscopy (SFG-VS). The hydrophobic functionalization rendered a concentration-dependent surface coverage of NPEI-ONPs, where the SFG-VS analysis exhibited the molecular rearrangement of its hydrophobic groups at the interface. The interaction of NPEI-ONPs with double-stranded DNA (dsDNA) is carried out to observe the relevance of the synthesized nanocomposites in the biomedical domain. The bulk-specific studies (i.e., thermal denaturation, viscometry, zeta (ζ) potential, and ATR-FTIR) reveal the condensation of dsDNA in the presence of NPEI-ONPs, making its structure more compact. The interface-sensitive SFG-VS showcased the impact of the dsDNA and NPEI-ONP interaction on the interfacial molecular behavior of NPEI-ONPs at the air-aqueous interface. Our results exhibit the potential of such hydrophobically functionalized ONPs as promising candidates for developing biomedical sealants, substrate coatings, and other biomedical domains.
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7
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Krzan M, Rey NG, Jarek E, Czakaj A, Santini E, Ravera F, Liggieri L, Warszynski P, Braunschweig B. Surface Properties of Saponin-Chitosan Mixtures. Molecules 2022; 27:7505. [PMID: 36364333 PMCID: PMC9658537 DOI: 10.3390/molecules27217505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/25/2022] [Accepted: 10/26/2022] [Indexed: 08/03/2024] Open
Abstract
The surface properties of saponin and saponin-chitosan mixtures were analysed as a function of their bulk mixing ratio using vibrational sum-frequency generation (SFG), surface tensiometry and dilational rheology measurements. Our experiments show that saponin-chitosan mixtures present some remarkable properties, such as a strong amphiphilicity of the saponin and high dilational viscoelasticity. We believe this points to the presence of chitosan in the adsorption layer, despite its complete lack of surface activity. We explain this phenomenon by electrostatic interactions between the saponin as an anionic surfactant and chitosan as a polycation, leading to surface-active saponin-chitosan complexes and aggregates. Analysing the SFG intensity of the O-H stretching bands from interfacial water molecules, we found that in the case of pH 3.4 for a mixture consisting of 0.1 g/L saponin and 0.001 g/L chitosan, the adsorption layer was electrically neutral. This conclusion from SFG spectra is corroborated by results from surface tensiometry showing a significant reduction in surface tension and effects on the dilational surface elasticity strictly at saponin/chitosan ratios, where SFG spectra indicate zero net charge at the air-water interface.
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Affiliation(s)
- Marcel Krzan
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Natalia García Rey
- Institute of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Ewelina Jarek
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Agnieszka Czakaj
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Eva Santini
- Institute of Condensed Matter and Technologies for Energy, Consiglio Nazionale delle Ricerche, Via Marini 6, 16149 Genova, Italy
| | - Francesca Ravera
- Institute of Condensed Matter and Technologies for Energy, Consiglio Nazionale delle Ricerche, Via Marini 6, 16149 Genova, Italy
| | - Libero Liggieri
- Institute of Condensed Matter and Technologies for Energy, Consiglio Nazionale delle Ricerche, Via Marini 6, 16149 Genova, Italy
| | - Piotr Warszynski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Björn Braunschweig
- Institute of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
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8
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Yu CC, Seki T, Chiang KY, Tang F, Sun S, Bonn M, Nagata Y. Polarization-Dependent Heterodyne-Detected Sum-Frequency Generation Spectroscopy as a Tool to Explore Surface Molecular Orientation and Ångström-Scale Depth Profiling. J Phys Chem B 2022; 126:6113-6124. [PMID: 35849538 PMCID: PMC9421650 DOI: 10.1021/acs.jpcb.2c02178] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Sum-frequency generation (SFG) spectroscopy provides
a unique optical
probe for interfacial molecules with interface-specificity and molecular
specificity. SFG measurements can be further carried out at different
polarization combinations, but the target of the polarization-dependent
SFG is conventionally limited to investigating the molecular orientation.
Here, we explore the possibility of polarization-dependent SFG (PD-SFG)
measurements with heterodyne detection (HD-PD-SFG). We stress that
HD-PD-SFG enables accurate determination of the peak amplitude, a
key factor of the PD-SFG data. Subsequently, we outline that HD-PD-SFG
can be used not only for estimating the molecular orientation but
also for investigating the interfacial dielectric profile and studying
the depth profile of molecules. We further illustrate the variety
of combined simulation and PD-SFG studies.
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Affiliation(s)
- Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kuo-Yang Chiang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Fujie Tang
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Shumei Sun
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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9
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Early sum frequency generation vibrational spectroscopic studies on peptides and proteins at interfaces. Biointerphases 2022; 17:031202. [PMID: 35525602 DOI: 10.1116/6.0001859] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This paper summarizes the early research results on studying proteins and peptides at interfaces using sum frequency generation (SFG) vibrational spectroscopy. SFG studies in the C-H stretching frequency region to examine the protein side-chain behavior and in the amide I frequency region to investigate the orientation and conformation of interfacial peptides/proteins are presented. The early chiral SFG research and SFG isotope labeling studies on interfacial peptides/proteins are also discussed. These early SFG studies demonstrate the feasibility of using SFG to elucidate interfacial molecular structures of peptides and proteins in situ, which built a foundation for later SFG investigations on peptides and proteins at interfaces.
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10
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Tan J, Ni Z, Ye S. Protein-Water Coupling Tunes the Anharmonicity of Amide I Modes in the Interfacial Membrane-Bound Proteins. J Chem Phys 2022; 156:105103. [DOI: 10.1063/5.0078632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Junjun Tan
- University of Science and Technology of China Hefei National Laboratory for Physical Sciences at the Microscale, China
| | - Zijian Ni
- University of Science and Technology of China Hefei National Laboratory for Physical Sciences at the Microscale Nanoscience Laboratory, China
| | - Shuji Ye
- University of Science and Technology of China Hefei National Laboratory for Physical Sciences at the Microscale, China
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11
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Lukas M, Schwidetzky R, Eufemio RJ, Bonn M, Meister K. Toward Understanding Bacterial Ice Nucleation. J Phys Chem B 2022; 126:1861-1867. [PMID: 35084861 PMCID: PMC8919256 DOI: 10.1021/acs.jpcb.1c09342] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Bacterial ice nucleators
(INs) are among the most effective ice
nucleators known and are relevant for freezing processes in agriculture,
the atmosphere, and the biosphere. Their ability to facilitate ice
formation is due to specialized ice-nucleating proteins (INPs) anchored
to the outer bacterial cell membrane, enabling the crystallization
of water at temperatures up to −2 °C. In this Perspective,
we highlight the importance of functional aggregation of INPs for
the exceptionally high ice nucleation activity of bacterial ice nucleators.
We emphasize that the bacterial cell membrane, as well as environmental
conditions, is crucial for a precise functional INP aggregation. Interdisciplinary
approaches combining high-throughput droplet freezing assays with
advanced physicochemical tools and protein biochemistry are needed
to link changes in protein structure or protein–water interactions
with changes on the functional level.
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Affiliation(s)
- Max Lukas
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | | | | | - Mischa Bonn
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Konrad Meister
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany.,University of Alaska Southeast, Juneau, Alaska 99801, United States
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12
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Chaudhary S, Kaur H, Kaur H, Rana B, Tomar D, Jena KC. Probing the Bovine Hemoglobin Adsorption Process and its Influence on Interfacial Water Structure at the Air-Water Interface. APPLIED SPECTROSCOPY 2021; 75:1497-1509. [PMID: 34346774 DOI: 10.1177/00037028211035157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
*These authors contributed equally to this work.The molecular-level insight of protein adsorption and its kinetics at interfaces is crucial because of its multifold role in diverse fundamental biological processes and applications. In the present study, the sum frequency generation (SFG) vibrational spectroscopy has been employed to demonstrate the adsorption process of bovine hemoglobin (BHb) protein molecules at the air-water interface at interfacial isoelectric point of the protein. It has been observed that surface coverage of BHb molecules significantly influences the arrangement of the protein molecules at the interface. The time-dependent SFG studies at two different frequencies in the fingerprint region elucidate the kinetics of protein denaturation process and its influence on the hydrogen-bonding network of interfacial water molecules at the air-water interface. The initial growth kinetics suggests the synchronized behavior of protein adsorption process with the structural changes in the interfacial water molecules. Interestingly, both the events carry similar characteristic time constants. However, the conformational changes in the protein structure due to the denaturation process stay for a long time, whereas the changes in water structure reconcile quickly. It is revealed that the protein denaturation process is followed by the advent of strongly hydrogen-bonded water molecules at the interface. In addition, we have also carried out the surface tension kinetics measurements to complement the findings of our SFG spectroscopic results.
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Affiliation(s)
- Shilpi Chaudhary
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
- Department of Applied Sciences, Punjab Engineering College (Deemed to be University), Chandigarh, India
| | - Harsharan Kaur
- Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar, India
| | - Harpreet Kaur
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
| | - Bhawna Rana
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
| | - Deepak Tomar
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
| | - Kailash C Jena
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
- Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar, India
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13
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Roeters SJ, Golbek TW, Bregnhøj M, Drace T, Alamdari S, Roseboom W, Kramer G, Šantl-Temkiv T, Finster K, Pfaendtner J, Woutersen S, Boesen T, Weidner T. Ice-nucleating proteins are activated by low temperatures to control the structure of interfacial water. Nat Commun 2021; 12:1183. [PMID: 33608518 PMCID: PMC7895962 DOI: 10.1038/s41467-021-21349-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 01/22/2021] [Indexed: 11/17/2022] Open
Abstract
Ice-nucleation active (INA) bacteria can promote the growth of ice more effectively than any other known material. Using specialized ice-nucleating proteins (INPs), they obtain nutrients from plants by inducing frost damage and, when airborne in the atmosphere, they drive ice nucleation within clouds, which may affect global precipitation patterns. Despite their evident environmental importance, the molecular mechanisms behind INP-induced freezing have remained largely elusive. We investigate the structural basis for the interactions between water and the ice-nucleating protein InaZ from the INA bacterium Pseudomonas syringae. Using vibrational sum-frequency generation (SFG) and two-dimensional infrared spectroscopy, we demonstrate that the ice-active repeats of InaZ adopt a β-helical structure in solution and at water surfaces. In this configuration, interaction between INPs and water molecules imposes structural ordering on the adjacent water network. The observed order of water increases as the interface is cooled to temperatures close to the melting point of water. Experimental SFG data combined with molecular-dynamics simulations and spectral calculations show that InaZ reorients at lower temperatures. This reorientation can enhance water interactions, and thereby the effectiveness of ice nucleation. Ice-nucleating proteins promote ice formation at high sub-zero temperatures, but the mechanism is still unclear. The authors investigate a model ice-nucleating protein at the air-water interface using vibrational sum frequency generation spectroscopy and simulations, revealing its reorientation at low temperatures, which increases contact with water molecules and promotes their ordering.
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Affiliation(s)
- Steven J Roeters
- Department of Chemistry, Aarhus University, Aarhus C, Denmark.,Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Mikkel Bregnhøj
- Department of Chemistry, Aarhus University, Aarhus C, Denmark
| | - Taner Drace
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Sarah Alamdari
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
| | - Winfried Roseboom
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Gertjan Kramer
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Tina Šantl-Temkiv
- Department of Biology, Aarhus University, Aarhus C, Denmark.,The Stellar Astrophysics Centre - SAC, Department of Physics and Astronomy, Aarhus University, Aarhus C, Denmark
| | - Kai Finster
- Department of Biology, Aarhus University, Aarhus C, Denmark.,The Stellar Astrophysics Centre - SAC, Department of Physics and Astronomy, Aarhus University, Aarhus C, Denmark
| | - Jim Pfaendtner
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
| | - Sander Woutersen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Thomas Boesen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark.,Interdisciplinary Nanoscience Center - iNano, Aarhus University, Aarhus C, Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, Aarhus C, Denmark. .,Department of Chemical Engineering, University of Washington, Seattle, WA, USA. .,Interdisciplinary Nanoscience Center - iNano, Aarhus University, Aarhus C, Denmark.
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14
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Lu H, Huang YC, Hunger J, Gebauer D, Cölfen H, Bonn M. Role of Water in CaCO 3 Biomineralization. J Am Chem Soc 2021; 143:1758-1762. [PMID: 33471507 PMCID: PMC7877725 DOI: 10.1021/jacs.0c11976] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Biomineralization occurs in aqueous
environments. Despite the ubiquity
and relevance of CaCO3 biomineralization, the role of water
in the biomineralization process has remained elusive. Here, we demonstrate
that water reorganization accompanies CaCO3 biomineralization
for sea urchin spine generation in a model system. Using surface-specific
vibrational spectroscopy, we probe the water at the interface of the
spine-associated protein during CaCO3 mineralization. Our
results show that, while the protein structure remains unchanged,
the structure of interfacial water is perturbed differently in the
presence of both Ca2+ and CO32– compared to the addition of only Ca2+. This difference
is attributed to the condensation of prenucleation mineral species.
Our findings are consistent with a nonclassical mineralization pathway
for sea urchin spine generation and highlight the importance of protein
hydration in biomineralization.
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Affiliation(s)
- Hao Lu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yu-Chieh Huang
- Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstrasse 10, Konstanz 78464, Germany
| | - Johannes Hunger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Denis Gebauer
- Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstrasse 10, Konstanz 78464, Germany.,Institute of Inorganic Chemistry, Leibniz University of Hannover, 30167 Hannover, Germany
| | - Helmut Cölfen
- Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstrasse 10, Konstanz 78464, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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15
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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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16
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Wang W, Tan J, Ye S. Unsaturated Lipid Accelerates Formation of Oligomeric β-Sheet Structure of GP41 Fusion Peptide in Model Cell Membrane. J Phys Chem B 2020; 124:5169-5176. [PMID: 32453953 DOI: 10.1021/acs.jpcb.0c02464] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membrane fusion of the viral and host cell membranes is the initial step of virus infection and is catalyzed by fusion peptides. Although the β-sheet structure of fusion peptides has been proposed to be the most important fusion-active conformation, it is still very challenging to experimentally identify different types of β-sheet structures at the cell membrane surface in situ and in real time. In this work, we demonstrate that the interface-sensitive amide II spectral signals of protein backbones, generated by the sum frequency generation vibrational spectroscopy, provide a sensitive probe for directly capturing the formation of oligomeric β-sheet structure of fusion peptides. Using human immunodeficiency virus (HIV) glycoprotein GP41 fusing peptide (FP23) as the model, we find that formation speed of oligomeric β-sheet structure depends on lipid unsaturation. The unsaturated lipid such as POPG can accelerate formation of oligomeric β-sheet structure of FP23. The β-sheet structure is more deeply inserted into the hydrophobic region of the POPG bilayer than the α-helical segment. This work will pave the way for future researches on capturing intermediate structures during membrane fusion processes and revealing the fusion mechanism.
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Affiliation(s)
- Wenting Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Junjun Tan
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Shuji Ye
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
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17
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Seki T, Yu CC, Yu X, Ohto T, Sun S, Meister K, Backus EHG, Bonn M, Nagata Y. Decoding the molecular water structure at complex interfaces through surface-specific spectroscopy of the water bending mode. Phys Chem Chem Phys 2020; 22:10934-10940. [PMID: 32373844 DOI: 10.1039/d0cp01269f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The structure of interfacial water determines atmospheric chemistry, wetting properties of materials, and protein folding. The challenge of investigating the properties of specific interfacial water molecules has frequently been confronted using surface-specific sum-frequency generation (SFG) vibrational spectroscopy using the O-H stretch mode. While perfectly suited for the water-air interface, for complex interfaces, a potential complication arises from the contribution of hydroxyl or amine groups of non-water species present at the surface, such as surface hydroxyls on minerals, or O-H and N-H groups contained in proteins. Here, we present a protocol to extract the hydrogen bond strength selectively of interfacial water, through the water bending mode. The bending mode vibrational frequency distribution provides a new avenue for unveiling the hydrogen bonding structure of interfacial water at complex aqueous interfaces. We demonstrate this method for the water-CaF2 and water-protein interfaces. For the former, we show that this method can indeed single out water O-H groups from surface hydroxyls, and that with increasing pH, the hydrogen-bonded network of interfacial water strengthens. Furthermore, we unveil enhanced hydrogen bonding of water, compared to bulk water, at the interface with human serum albumin proteins, a prototypical bio-interface.
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Affiliation(s)
- Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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18
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Adams EM, Lampret O, König B, Happe T, Havenith M. Solvent dynamics play a decisive role in the complex formation of biologically relevant redox proteins. Phys Chem Chem Phys 2020; 22:7451-7459. [PMID: 32215444 DOI: 10.1039/d0cp00267d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron transfer processes between proteins are vital in many biological systems. Yet, the role of the solvent in influencing these redox reactions remains largely unknown. In this study, terahertz-time domain spectroscopy (THz-TDS) is used to probe the collective hydration dynamics of flavoenzyme ferredoxin-NADP+-reductase (FNR), electron transfer protein ferredoxin-1 (PetF), and the transient complex that results from their interaction. Results reveal changes in the sub-picosecond hydration dynamics that are dependent upon the surface electrostatic properties of the individual proteins and the transient complex. Retarded solvent dynamics of 8-9 ps are observed for FNR, PetF, and the FNR:PetF transient complex. Binding of the FNR:PetF complex to the substrate NADP+ results in bulk-like solvent dynamics of 7 ps, showing that formation of the ternary complex is entropically favored. Our THz measurements reveal that the electrostatic interaction of the protein surface with water results in charge sensitive changes in the solvent dynamics. Complex formation between the positively charged FNR:NADP+ pre-complex and the negatively charged PetF is not only entropically favored, but in addition the solvent reorganization into more bulk-like water assists the molecular recognition process. The change in hydration dynamics observed here suggests that the interaction with the solvent plays a significant role in mediating electron transfer processes between proteins.
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Affiliation(s)
- Ellen M Adams
- Lehrstuhl für Physkalische Chemie II, Ruhr Universität Bochum, 44801 Bochum, Germany.
| | - Oliver Lampret
- AG Photobiotechnologie, Ruhr Universität Bochum, 44801 Bochum, Germany
| | - Benedikt König
- Lehrstuhl für Physkalische Chemie II, Ruhr Universität Bochum, 44801 Bochum, Germany.
| | - Thomas Happe
- AG Photobiotechnologie, Ruhr Universität Bochum, 44801 Bochum, Germany
| | - Martina Havenith
- Lehrstuhl für Physkalische Chemie II, Ruhr Universität Bochum, 44801 Bochum, Germany.
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19
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Lukas M, Schwidetzky R, Kunert AT, Pöschl U, Fröhlich-Nowoisky J, Bonn M, Meister K. Electrostatic Interactions Control the Functionality of Bacterial Ice Nucleators. J Am Chem Soc 2020; 142:6842-6846. [PMID: 32223131 DOI: 10.1021/jacs.9b13069] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Bacterial ice-nucleating proteins (INPs) promote heterogeneous ice nucleation more efficiently than any other material. The details of their working mechanism remain elusive, but their high activity has been shown to involve the formation of functional INP aggregates. Here we reveal the importance of electrostatic interactions for the activity of INPs from the bacterium Pseudomonas syringae by combining a high-throughput ice nucleation assay with surface-specific sum-frequency generation spectroscopy. We determined the charge state of nonviable P. syringae as a function of pH by monitoring the degree of alignment of the interfacial water molecules and the corresponding ice nucleation activity. The net charge correlates with the ice nucleation activity of the INP aggregates, which is minimal at the isoelectric point. In contrast, the activity of INP monomers is less affected by pH changes. We conclude that electrostatic interactions play an essential role in the formation of the highly efficient functionally aligned INP aggregates, providing a mechanism for promoting aggregation under conditions of stress that prompt the bacteria to nucleate ice.
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Affiliation(s)
- M Lukas
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - R Schwidetzky
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - A T Kunert
- Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - U Pöschl
- Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | | | - M Bonn
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - K Meister
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany.,University of Alaska Southeast, Juneau, Alaska 99801, United States
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20
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Hosseinpour S, Roeters SJ, Bonn M, Peukert W, Woutersen S, Weidner T. Structure and Dynamics of Interfacial Peptides and Proteins from Vibrational Sum-Frequency Generation Spectroscopy. Chem Rev 2020; 120:3420-3465. [DOI: 10.1021/acs.chemrev.9b00410] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Saman Hosseinpour
- Institute of Particle Technology (LFG), Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | | | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Sander Woutersen
- Van’t Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 EP Amsterdam, The Netherlands
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
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21
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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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22
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Richert ME, Gochev GG, Braunschweig B. Specific Ion Effects of Trivalent Cations on the Structure and Charging State of β-Lactoglobulin Adsorption Layers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11299-11307. [PMID: 31398284 DOI: 10.1021/acs.langmuir.9b01803] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The properties of proteins at interfaces are important to many processes as well as in soft matter materials such as aqueous foam. Particularly, the protein interfacial behavior is strongly linked to different factors like the solution pH or the presence of electrolytes. Here, the nature of the electrolyte ions can significantly modify the interfacial properties of proteins. Therefore, molecular level studies on interfacial structures and charging states are needed. In this work, we addressed the effects of Y3+ and Nd3+ cations on the adsorption of the whey protein β-lactoglobulin (BLG) at air-water interfaces as the function of electrolyte concentration. Both cations caused very similar but dramatic changes at the interface and in the bulk solution. Here, measurements of the electrophoretic mobility and with vibrational sum-frequency generation (SFG) spectroscopy were applied and consistently showed a reversal of the BLG net charge at remarkably low ion concentrations of 30 (bulk) and 40 (interface) μM of Y3+ or Nd3+ for a BLG concentration of 15 μM. SFG spectra of carboxylate stretching vibrations from Asp or Glu residues of interfacial BLG showed significant changes in the resonance frequency, which we associate to specific and efficient binding of Y3+ or Nd3+ ions to the proteins carboxylate groups. Characteristic reentrant condensation for BLG moieties with bound trivalent ions was found in a broad concentration range around the point of zero net charge. The highest colloidal stability of BLG was found for ion concentrations <20 μM and >50 μM. Investigations on macroscopic foams from BLG solutions revealed the existence of structure-property relations between the interfacial charging state and the foam stability. In fact, a minimum in foam stability at 20 μM ion concentration was found when the interfacial net charge was negligible. At this concentration, we propose that the persistent BLG molecules and weakly charged BLG aggregates drive foam stability, while outside the bulk reentrant zone the electrostatic disjoining pressure inside foam lamellae dominates foam stability. Our results provide new information on the charge reversal at the liquid-gas interface of protein/ion dispersions. Therefore, we see our findings as an important step in the clarification of reentrant condensation effects at interfaces and their relevance to foam stability.
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Affiliation(s)
- Manuela E Richert
- Institute of Physical Chemistry and Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster Corrensstraße 28/30 , 48149 Münster , Germany
| | - Georgi G Gochev
- Institute of Physical Chemistry and Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster Corrensstraße 28/30 , 48149 Münster , Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry and Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster Corrensstraße 28/30 , 48149 Münster , Germany
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23
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Guckeisen T, Hosseinpour S, Peukert W. Isoelectric Points of Proteins at the Air/Liquid Interface and in Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5004-5012. [PMID: 30892047 DOI: 10.1021/acs.langmuir.9b00311] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Electrostatic interactions play essential roles in determining the function, colloidal stability, and adsorption of proteins on different surfaces and interfaces. Therefore, a molecular-level understanding of the charge state of the proteins under different conditions is required to explain their macroscopic properties. In this study, we have employed an inherently surface-sensitive spectroscopic tool, sum frequency generation spectroscopy, to determine the charge state of a wide range of proteins as a function of pH at the air/liquid interface via measurement of the degree of orientation of water molecules. We compared the isoelectric point (IEP) of the 12 investigated proteins at the air/liquid interface with that in the bulk solution obtained through zeta potential measurements. Ellipsometry is performed to determine the film thickness at the air/liquid interface at different charge states. In particular, protein aggregation at the IEP is reflected by increased film thickness. For all proteins, the interfacial point of zero charge is close (with less than 1 pH unit variation) to that in the bulk solution.
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Affiliation(s)
- Tobias Guckeisen
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität-Erlangen-Nürnberg (FAU) , Cauerstraße 4 , 91058 Erlangen , Germany
| | - Saman Hosseinpour
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität-Erlangen-Nürnberg (FAU) , Cauerstraße 4 , 91058 Erlangen , Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität-Erlangen-Nürnberg (FAU) , Cauerstraße 4 , 91058 Erlangen , Germany
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24
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Schulze-Zachau F, Braunschweig B. C nTAB/polystyrene sulfonate mixtures at air-water interfaces: effects of alkyl chain length on surface activity and charging state. Phys Chem Chem Phys 2019; 21:7847-7856. [PMID: 30916092 DOI: 10.1039/c9cp01107b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Binding and phase behavior of oppositely charged polyelectrolytes and surfactants with different chain lengths were studied in aqueous bulk solutions and at air-water interfaces. In particular, we have investigated the polyanion poly(sodium 4-styrenesulfonate) (NaPSS) and the cationic surfactants dodecyltrimethylammonium bromide (C12TAB), tetradecyltrimethylammonium bromide (C14TAB) and cetyltrimethylammonium bromide (C16TAB). In order to reveal the surfactant/polyelectrolyte binding, aggregation and phase separation of the mixtures, we have varied the NaPSS concentration systematically and have kept the surfactant concentration fixed at 1/6 of the respective critical micelle concentration. Information on the behavior in the bulk solution was gained by electrophoretic mobility and turbidity measurements, while the surface properties were studied using surface tension measurements and vibrational sum-frequency generation (SFG). This has enabled us to relate bulk to interfacial properties with respect to the charging state and the surfactants' binding efficiency. We found that the latter two are strongly dependent on the alkyl chain length of the surfactant and that binding is much more efficient as the alkyl chain length of the surfactant increases. This also results in a different phase behavior as shown by turbidity measurements of the bulk solutions. Charge neutral aggregates that are forming in the bulk adsorb onto the air-water interface - an effect that is likely caused by the increased hydrophobicity of CnTAB/PSS complexes. This conclusion is corroborated by SFG spectroscopy, where we observe a decrease in the intensity of O-H stretching bands, which is indicative of a decrease in surface charging and the formation of interfaces with negligible net charge. Particularly at mixing ratios that are in the equilibrium two-phase region, we observe weak O-H intensities and thus surface charging.
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Affiliation(s)
- Felix Schulze-Zachau
- Institute of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany.
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25
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Ultrafast energy relaxation dynamics of amide I vibrations coupled with protein-bound water molecules. Nat Commun 2019; 10:1010. [PMID: 30824834 PMCID: PMC6397197 DOI: 10.1038/s41467-019-08899-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 02/06/2019] [Indexed: 12/11/2022] Open
Abstract
The influence of hydration water on the vibrational energy relaxation in a protein holds the key to understand ultrafast protein dynamics, but its detection is a major challenge. Here, we report measurements on the ultrafast vibrational dynamics of amide I vibrations of proteins at the lipid membrane/H2O interface using femtosecond time-resolved sum frequency generation vibrational spectroscopy. We find that the relaxation time of the amide I mode shows a very strong dependence on the H2O exposure, but not on the D2O exposure. This observation indicates that the exposure of amide I bond to H2O opens up a resonant relaxation channel and facilitates direct resonant vibrational energy transfer from the amide I mode to the H2O bending mode. The protein backbone motions can thus be energetically coupled with protein-bound water molecules. Our findings highlight the influence of H2O on the ultrafast structure dynamics of proteins.
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26
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Naseri E, Hajisafari M, Kosari A, Talari M, Hosseinpour S, Davoodi A. Inhibitive effect of Clopidogrel as a green corrosion inhibitor for mild steel; statistical modeling and quantum Monte Carlo simulation studies. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.08.050] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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27
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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
![]()
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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28
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Schulze-Zachau F, Bachmann S, Braunschweig B. Effects of Ca 2+ Ion Condensation on the Molecular Structure of Polystyrene Sulfonate at Air-Water Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11714-11722. [PMID: 30188134 PMCID: PMC6170951 DOI: 10.1021/acs.langmuir.8b02631] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/05/2018] [Indexed: 06/02/2023]
Abstract
The structure of poly(sodium 4-styrenesulfonate) (NaPSS) polyelectrolytes at air-water interfaces was investigated with tensiometry, ellipsometry, and vibrational sum-frequency generation (SFG) in the presence of low and high CaCl2 concentrations. In addition, we have studied the foaming behavior of 20 mM NaPSS solutions to relate the PSS molecular structure at air-water interfaces to foam properties. PSS polyelectrolytes without additional salt exhibited significant surface activity, which can be tuned further by additions of CaCl2. The hydrophobicity of the backbone due to incomplete sulfonation during synthesis is one origin, whereas the effective charge of the polyelectrolyte chain is shown to play another major role. At low salt concentrations, we propose that the polyelectrolyte is forming a layered structure. The hydrophobic parts are likely to be located directly at the interface in loops, whereas the hydrophilic parts are at low concentrations stretched out into near-interface regions in tails. Increasing the Ca2+ concentration leads to ion condensation, a collapse of the tails, and likely to Ca2+ intra- and intermolecular bridges between polyelectrolytes at the interface. The increase in both surface excess and foam stability originates from changes in the polyelectrolyte's hydrophobicity due to Ca2+ condensation onto the PSS polyanions. Consequently, charge screening at the interface is enhanced and repulsive electrostatic interactions are reduced. Furthermore, SFG spectra of O-H stretching bands reveal a decrease in intensity of the low-frequency branch when c(Ca2+) is increased whereas the high-frequency branch of O-H stretching modes persists even for 1 M CaCl2. This originates from the remaining net charge of the PSS polyanions at the air-water interface that is not fully compensated by condensation of Ca2+ ions and leads to electric-field-induced contributions to the SFG spectra of interfacial H2O. A charge reversal of the PSS net charge at the air-water interface is not observed and is consistent with bulk electrophoretic mobility measurements.
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Affiliation(s)
- Felix Schulze-Zachau
- Institute
of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Silvia Bachmann
- Institute
of Particle Technology (LFG), Friedrich-Alexander-Universität
Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany
| | - Björn Braunschweig
- Institute
of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
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29
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Combined surface analysis methods. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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30
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Zhang B, Tan J, Li C, Zhang J, Ye S. Amide I SFG Spectral Line Width Probes the Lipid-Peptide and Peptide-Peptide Interactions at Cell Membrane In Situ and in Real Time. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7554-7560. [PMID: 29804455 DOI: 10.1021/acs.langmuir.8b00946] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The balance of lipid-peptide and peptide-peptide interactions at cell membrane is essential to a large variety of cellular processes. In this study, we have experimentally demonstrated for the first time that sum frequency generation vibrational spectroscopy can be used to probe the peptide-peptide and lipid-peptide interactions in cell membrane in situ and in real time by determination of the line width of amide I band of protein backbone. Using a "benchmark" model of α-helical WALP23, it is found that the dominated lipid-peptide interaction causes a narrow line width of the amide I band, whereas the peptide-peptide interaction can markedly broaden the line width. When WALP23 molecules insert into the lipid bilayer, a quite narrow line width of the amide I band is observed because of the lipid-peptide interaction. In contrast, when the peptide lies down on the bilayer surface, the line width of amide I band becomes very broad owing to the peptide-peptide interaction. In terms of the real-time change in the line width, the transition from peptide-peptide interaction to lipid-peptide interaction is monitored during the insertion of WALP23 into 1,2-dipalmitoyl- sn-glycero-3-phospho-(1'- rac-glycerol) (DPPG) lipid bilayer. The dephasing time of a pure α-helical WALP23 in 1-palmitoyl-2-oleoyl- sn-glycero-3-phospho-(1'- rac-glycerol) and DPPG bilayer is determined to be 2.2 and 0.64 ps, respectively. The peptide-peptide interaction can largely accelerate the dephasing time.
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31
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Koepf E, Richert M, Braunschweig B, Schroeder R, Brezesinski G, Friess W. Impact of formulation pH on physicochemical protein characteristics at the liquid-air interface. Int J Pharm 2018; 541:234-245. [DOI: 10.1016/j.ijpharm.2018.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 12/31/2022]
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Streubel S, Schulze-Zachau F, Weißenborn E, Braunschweig B. Ion Pairing and Adsorption of Azo Dye/C 16TAB Surfactants at the Air-Water Interface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:27992-28000. [PMID: 29285205 PMCID: PMC5742476 DOI: 10.1021/acs.jpcc.7b08924] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/29/2017] [Indexed: 06/01/2023]
Abstract
Mixed layers of 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate (Sunset Yellow, SSY) and cetyltrimethylammonium bromide (C16TAB) at the air-water interface were studied using vibrational sum-frequency generation (SFG) and dynamic surface tension measurements. In the bulk, addition of C16TAB to SSY aqueous solution causes substantial changes in UV/vis absorption spectra, which originate from strong electrostatic interactions between the anionic SSY azo dye with the cationic C16TAB surfactant. These interactions are a driving force for the formation of SSY/C16TAB ion pairs. The latter are found to be highly surface active while free SSY molecules show no surface activity. Dynamic SFG as well as surface tension measurements at low SSY concentrations reveal that free C16TAB surfactants adsorb at the air-water interface on time scales <1 s where they initially form the dominating surface species, but on longer time scales free C16TAB is exchanged by SSY/C16TAB ion pairs. This causes a dramatic reduction of the surface tension to 35 mN/m but also in foam stability. These changes are accompanied by a substantial loss in SFG intensity from O-H stretching bands around 3200 and 3450 cm-1, which we relate to a decrease in surface charging due to adsorption of ion pairs with no or negligible net charges. For SSY/C16TAB molar ratios >0.5, the O-H bands in SFG spectra are reduced to very low intensities and are indicative to electrically neutral SSY/C16TAB ion pairs. This conclusion is corroborated by an analysis of macroscopic foams, which become highly instable in the presence of neutral SSY/C16TAB ion pairs. From an analysis of SFG spectra of air-water interfaces, we show that the electrostatic repulsion forces inside the ubiquitous foam films are reduced and thus remove the major stabilization mechanism within macroscopic foam.
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Affiliation(s)
- Saskia Streubel
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Felix Schulze-Zachau
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Eric Weißenborn
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
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33
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Meister K, Paananen A, Speet B, Lienemann M, Bakker HJ. Molecular Structure of Hydrophobins Studied with Site-Directed Mutagenesis and Vibrational Sum-Frequency Generation Spectroscopy. J Phys Chem B 2017; 121:9398-9402. [PMID: 28967753 PMCID: PMC5647563 DOI: 10.1021/acs.jpcb.7b08865] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 09/14/2017] [Indexed: 01/31/2023]
Abstract
Hydrophobins are surface-active fungal proteins that adsorb to the water-air interface and self-assemble into amphiphilic, water-repelling films that have a surface elasticity that is an order of magnitude higher than other molecular films. Here we use surface-specific sum-frequency generation spectroscopy (VSFG) and site-directed mutagenesis to study the properties of class I hydrophobin (HFBI) films from Trichoderma reesei at the molecular level. We identify protein specific HFBI signals in the frequency region 1200-1700 cm-1 that have not been observed in previous VSFG studies on proteins. We find evidence that the aspartic acid residue (D30) next to the hydrophobic patch is involved in lateral intermolecular protein interactions, while the two aspartic acid residues (D40, D43) opposite to the hydrophobic patch are primarily interacting with the water solvent.
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Affiliation(s)
- K. Meister
- AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - A. Paananen
- VTT Technical Research Centre of Finland Ltd, Tietotie, FI-02150 Espoo, Finland
| | - B. Speet
- AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - M. Lienemann
- VTT Technical Research Centre of Finland Ltd, Tietotie, FI-02150 Espoo, Finland
| | - H. J. Bakker
- AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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Schöne AC, Roch T, Schulz B, Lendlein A. Evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer techniques. J R Soc Interface 2017; 14:20161028. [PMID: 28468918 PMCID: PMC5454283 DOI: 10.1098/rsif.2016.1028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/05/2017] [Indexed: 12/18/2022] Open
Abstract
Polymeric biomaterials are of specific relevance in medical and pharmaceutical applications due to their wide range of tailorable properties and functionalities. The knowledge about interactions of biomaterials with their biological environment is of crucial importance for developing highly sophisticated medical devices. To achieve optimal in vivo performance, a description at the molecular level is required to gain better understanding about the surface of synthetic materials for tailoring their properties. This is still challenging and requires the comprehensive characterization of morphological structures, polymer chain arrangements and degradation behaviour. The review discusses selected aspects for evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer methods as powerful techniques for studying interfacial properties, such as morphological and degradation processes. The combination of spectroscopic, microscopic and scattering methods with the Langmuir techniques adapted to polymers can substantially improve the understanding of their in vivo behaviour.
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Affiliation(s)
- Anne-Christin Schöne
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany
| | - Toralf Roch
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany
- Helmholtz Virtual Institute-Multifunctional Biomaterials for Medicine, Kantstrasse 55, 14513 Teltow, Germany
| | - Burkhard Schulz
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany
| | - Andreas Lendlein
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany
- Helmholtz Virtual Institute-Multifunctional Biomaterials for Medicine, Kantstrasse 55, 14513 Teltow, Germany
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35
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Meister K, Roeters SJ, Paananen A, Woutersen S, Versluis J, Szilvay GR, Bakker HJ. Observation of pH-Induced Protein Reorientation at the Water Surface. J Phys Chem Lett 2017; 8:1772-1776. [PMID: 28345915 PMCID: PMC5451149 DOI: 10.1021/acs.jpclett.7b00394] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 03/27/2017] [Indexed: 05/23/2023]
Abstract
Hydrophobins are surface-active proteins that form a hydrophobic, water-repelling film around aerial fungal structures. They have a compact, particle-like structure, in which hydrophilic and hydrophobic regions are spatially separated. This surface property renders them amphiphilic and is reminiscent of synthetic Janus particles. Here we report surface-specific chiral and nonchiral vibrational sum-frequency generation spectroscopy (VSFG) measurements of hydrophobins adsorbed to their natural place of action, the air-water interface. We observe that hydrophobin molecules undergo a reversible change in orientation (tilt) at the interface when the pH is varied. We explain this local orientation toggle from the modification of the interprotein interactions and the interaction of hydrophobin with the water solvent, following the pH-induced change of the charge state of particular amino acids.
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Affiliation(s)
- Konrad Meister
- AMOLF, Science Park 104, 1098XG Amsterdam, The Netherlands
| | - Steven J. Roeters
- Van
’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Arja Paananen
- VTT
Technical Research Centre of Finland Ltd., PO. Box 1000, FI-02044 VTT Espoo, Finland
| | - Sander Woutersen
- Van
’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jan Versluis
- AMOLF, Science Park 104, 1098XG Amsterdam, The Netherlands
| | - Géza R. Szilvay
- VTT
Technical Research Centre of Finland Ltd., PO. Box 1000, FI-02044 VTT Espoo, Finland
| | - Huib J. Bakker
- AMOLF, Science Park 104, 1098XG Amsterdam, The Netherlands
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36
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Schulze-Zachau F, Braunschweig B. Structure of Polystyrenesulfonate/Surfactant Mixtures at Air-Water Interfaces and Their Role as Building Blocks for Macroscopic Foam. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3499-3508. [PMID: 28318264 PMCID: PMC5391498 DOI: 10.1021/acs.langmuir.7b00400] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/17/2017] [Indexed: 05/26/2023]
Abstract
Air/water interfaces were modified by oppositely charged poly(sodium 4-styrenesulfonate) (NaPSS) and hexadecyltrimethylammonium bromide (CTAB) polyelectrolyte/surfactant mixtures and were studied on a molecular level with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry. In order to deduce structure property relations, our results on the interfacial molecular structure and lateral interactions of PSS-/CTA+ complexes were compared to the stability and structure of macroscopic foam as well as to bulk properties. For that, the CTAB concentration was fixed to 0.1 mM, while the NaPSS concentration was varied. At NaPSS monomer concentrations <0.1 mM, PSS-/CTA+ complexes start to replace free CTA+ surfactants at the interface and thus reduce the interfacial electric field in the process. This causes the O-H bands from interfacial H2O molecules in our SFG spectra to decrease substantially, which reach a local minimum in intensity close to equimolar concentrations. Once electrostatic repulsion is fully screened at the interface, hydrophobic PSS-/CTA+ complexes dominate and tend to aggregate at the interface and in the bulk solution. As a consequence, adsorbate layers with the highest film thickness, surface pressure, and dilatational elasticity are formed. These surface layers provide much higher stabilities and foamabilities of polyhedral macroscopic foams. Mixtures around this concentration show precipitation after a few days, while their surfaces to air are in a local equilibrium state. Concentrations >0.1 mM result in a significant decrease in surface pressure and a complete loss in foamability. However, SFG and surface dilatational rheology provide strong evidence for the existence of PSS-/CTA+ complexes at the interface. At polyelectrolyte concentrations >10 mM, air-water interfaces are dominated by an excess of free PSS- polyelectrolytes and small amounts of PSS-/CTA+ complexes which, however, provide higher foam stabilities compared to CTAB free foams. The foam structure undergoes a transition from wet to polyhedral foams during the collapse.
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Affiliation(s)
- Felix Schulze-Zachau
- Institute
of Physical Chemistry, Westfälische
Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
- Erlangen
Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg
(FAU), Paul-Gordan-Strasse
6, 91052 Erlangen, Germany
| | - Björn Braunschweig
- Institute
of Physical Chemistry, Westfälische
Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
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37
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Dinkel R, Peukert W, Braunschweig B. In situ spectroscopy of ligand exchange reactions at the surface of colloidal gold and silver nanoparticles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:133002. [PMID: 28198355 DOI: 10.1088/1361-648x/aa5a3c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Gold and silver nanoparticles with their tunable optical and electronic properties are of great interest for a wide range of applications. Often the ligands at the surface of the nanoparticles have to be exchanged in a second step after particle formation in order to obtain a desired surface functionalization. For many techniques, this process is not accessible in situ. In this review, we present second-harmonic scattering (SHS) as an inherently surface sensitive and label-free optical technique to probe the ligand exchange at the surface of colloidal gold and silver nanoparticles in situ and in real time. First, a brief introduction to SHS and basic features of the SHS of nanoparticles are given. After that, we demonstrate how the SHS intensity decrease can be correlated to the thiol coverage which allows for the determination of the Gibbs free energy of adsorption and the surface coverage.
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Affiliation(s)
- Rebecca Dinkel
- Institute of Particle Technology (LFG), Friedrich-Alexander University Erlangen-Nürnberg, Cauerstraße 4, 91058 Erlangen, Germany
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38
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Ulaganathan V, Retzlaff I, Won J, Gochev G, Gehin-Delval C, Leser M, Noskov B, Miller R. β-Lactoglobulin adsorption layers at the water/air surface: 1. Adsorption kinetics and surface pressure isotherm: Effect of pH and ionic strength. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2016.03.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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39
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Meister K, Paananen A, Bakker HJ. Identification of the response of protein N–H vibrations in vibrational sum-frequency generation spectroscopy of aqueous protein films. Phys Chem Chem Phys 2017; 19:10804-10807. [PMID: 28265595 DOI: 10.1039/c6cp08325k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We study the response of protein N–H vibrations in aqueous hydrophobin films using vibrational sum- frequency generation spectroscopy.
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Affiliation(s)
| | - A. Paananen
- VTT Technical Research Centre of Finland Ltd
- FI-02150 Espoo
- Finland
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40
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Meister K, Bäumer A, Szilvay GR, Paananen A, Bakker HJ. Self-Assembly and Conformational Changes of Hydrophobin Classes at the Air-Water Interface. J Phys Chem Lett 2016; 7:4067-4071. [PMID: 27690211 DOI: 10.1021/acs.jpclett.6b01917] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We use surface-specific vibrational sum-frequency generation spectroscopy (VSFG) to study the structure and self-assembling mechanism of the class I hydrophobin SC3 from Schizophyllum commune and the class II hydrophobin HFBI from Trichoderma reesei. We find that both hydrophobins readily accumulate at the water-air interface and form rigid, highly ordered protein films that give rise to prominent VSFG signals. We identify several resonances that are associated with β-sheet structures and assign them to the central β-barrel core present in both proteins. Differences between the hydrophobin classes are observed in their interfacial self-assembly. For HFBI, we observe no changes in conformation upon adsorption to the water surface. For SC3, we observe an increase in β-sheet-specific signals that supports a surface-driven self-assembly mechanism in which the central β-barrel remains intact and stacks into a larger-scale architecture, amyloid-like rodlets.
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Affiliation(s)
- Konrad Meister
- FOM-Institute for Atomic and Molecular Physics AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Alexander Bäumer
- Physical Chemistry II, Ruhr University Bochum , Universitätsstr. 150, 44801 Bochum, Germany
| | - Geza R Szilvay
- VTT Technical Research Centre of Finland Ltd, Tietotie 2, FI-02150 Espoo, Finland
| | - Arja Paananen
- VTT Technical Research Centre of Finland Ltd, Tietotie 2, FI-02150 Espoo, Finland
| | - Huib J Bakker
- FOM-Institute for Atomic and Molecular Physics AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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41
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Braunschweig B, Schulze-Zachau F, Nagel E, Engelhardt K, Stoyanov S, Gochev G, Khristov K, Mileva E, Exerowa D, Miller R, Peukert W. Specific effects of Ca(2+) ions and molecular structure of β-lactoglobulin interfacial layers that drive macroscopic foam stability. SOFT MATTER 2016; 12:5995-6004. [PMID: 27337699 PMCID: PMC5048339 DOI: 10.1039/c6sm00636a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/12/2016] [Indexed: 06/01/2023]
Abstract
β-Lactoglobulin (BLG) adsorption layers at air-water interfaces were studied in situ with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry as a function of bulk Ca(2+) concentration. The relation between the interfacial molecular structure of adsorbed BLG and the interactions with the supporting electrolyte is additionally addressed on higher length scales along the foam hierarchy - from the ubiquitous air-water interface through thin foam films to macroscopic foam. For concentrations <1 mM, a strong decrease in SFG intensity from O-H stretching bands and a slight increase in layer thickness and surface pressure are observed. A further increase in Ca(2+) concentrations above 1 mM causes an apparent change in the polarity of aromatic C-H stretching vibrations from interfacial BLG which we associate to a charge reversal at the interface. Foam film measurements show formation of common black films at Ca(2+) concentrations above 1 mM due to considerable decrease of the stabilizing electrostatic disjoining pressure. These observations also correlate with a minimum in macroscopic foam stability. For concentrations >30 mM Ca(2+), micrographs of foam films show clear signatures of aggregates which tend to increase the stability of foam films. Here, the interfacial layers have a higher surface dilatational elasticity. In fact, macroscopic foams formed from BLG dilutions with high Ca(2+) concentrations where aggregates and interfacial layers with higher elasticity are found, showed the highest stability with much smaller bubble sizes.
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Affiliation(s)
- Björn Braunschweig
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany. and Cluster of Excellence Engineering of Advanced Materials (EAM), Nägelsbachstr. 49b, 91052 Erlangen, Germany and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052 Erlangen, Germany and Interdisciplinary Center of Functional Particle Systems, Haberstraße 9a, 91058 Erlangen, Germany
| | - Felix Schulze-Zachau
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany. and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052 Erlangen, Germany and Interdisciplinary Center of Functional Particle Systems, Haberstraße 9a, 91058 Erlangen, Germany
| | - Eva Nagel
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany.
| | - Kathrin Engelhardt
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany.
| | - Stefan Stoyanov
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Georgi Gochev
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria and Max-Planck-Institute of Colloids and Interfaces, 14476 Golm/Potsdam, Germany
| | - Khr Khristov
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Elena Mileva
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Dotchi Exerowa
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Reinhard Miller
- Max-Planck-Institute of Colloids and Interfaces, 14476 Golm/Potsdam, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany. and Cluster of Excellence Engineering of Advanced Materials (EAM), Nägelsbachstr. 49b, 91052 Erlangen, Germany and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052 Erlangen, Germany and Interdisciplinary Center of Functional Particle Systems, Haberstraße 9a, 91058 Erlangen, Germany
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42
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Strazdaite S, Meister K, Bakker HJ. Orientation of polar molecules near charged protein interfaces. Phys Chem Chem Phys 2016; 18:7414-8. [DOI: 10.1039/c5cp06372h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the orientation of water and urea molecules and protein amide vibrations at aqueous α-lactalbumin and α-lactalbumin/urea interfaces using heterodyne-detected vibrational sum frequency generation.
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Affiliation(s)
- Simona Strazdaite
- FOM-Institute for Atomic and Molecular Physics AMOLF
- Amsterdam 1098 XG
- The Netherlands
| | - Konrad Meister
- FOM-Institute for Atomic and Molecular Physics AMOLF
- Amsterdam 1098 XG
- The Netherlands
| | - Huib J. Bakker
- FOM-Institute for Atomic and Molecular Physics AMOLF
- Amsterdam 1098 XG
- The Netherlands
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43
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Beierlein FR, Clark T, Braunschweig B, Engelhardt K, Glas L, Peukert W. Carboxylate Ion Pairing with Alkali-Metal Ions for β-Lactoglobulin and Its Role on Aggregation and Interfacial Adsorption. J Phys Chem B 2015; 119:5505-17. [PMID: 25825918 DOI: 10.1021/acs.jpcb.5b01944] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a combined experimental and computational study of the whey protein β-lactoglobulin (BLG) in different electrolyte solutions. Vibrational sum-frequency generation (SFG) and ellipsometry were used to investigate the molecular structure of BLG modified air-water interfaces as a function of LiCl, NaCl, and KCl concentrations. Molecular dynamics (MD) simulations and thermodynamic integration provided details of the ion pairing of protein surface residues with alkali-metal cations. Our results at pH 6.2 indicate that BLG at the air-water interface forms mono- and bilayers preferably at low and high ionic strength, respectively. Results from SFG spectroscopy and ellipsometry are consistent with intimate ion pairing of alkali-metal cations with aspartate and glutamate carboxylates, which is shown to be more effective for smaller cations (Li(+) and Na(+)). MD simulations show not only carboxylate-alkali-metal ion pairs but also ion multiplets with the alkali-metal ion in a bridging position between two or more carboxylates. Consequently, alkali-metal cations can bridge carboxylates not only within a monomer but also between monomers, thus providing an important dimerization mechanism between hydrophilic surface patches.
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Affiliation(s)
- Frank R Beierlein
- †Computer-Chemie-Centrum and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 25, 91052 Erlangen, Germany.,‡Cluster of Excellence Engineering of Advanced Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 49b, 91052 Erlangen, Germany
| | - Timothy Clark
- †Computer-Chemie-Centrum and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 25, 91052 Erlangen, Germany.,‡Cluster of Excellence Engineering of Advanced Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 49b, 91052 Erlangen, Germany.,∥Centre for Molecular Design, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth PO1 2DY, United Kingdom
| | - Björn Braunschweig
- ‡Cluster of Excellence Engineering of Advanced Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 49b, 91052 Erlangen, Germany.,§Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 4, 91058 Erlangen, Germany
| | - Kathrin Engelhardt
- §Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 4, 91058 Erlangen, Germany
| | - Lena Glas
- §Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 4, 91058 Erlangen, Germany
| | - Wolfgang Peukert
- ‡Cluster of Excellence Engineering of Advanced Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 49b, 91052 Erlangen, Germany.,§Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 4, 91058 Erlangen, Germany
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Meister K, Lotze S, Olijve LLC, DeVries AL, Duman JG, Voets IK, Bakker HJ. Investigation of the Ice-Binding Site of an Insect Antifreeze Protein Using Sum-Frequency Generation Spectroscopy. J Phys Chem Lett 2015; 6:1162-1167. [PMID: 26262966 DOI: 10.1021/acs.jpclett.5b00281] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We study the ice-binding site (IBS) of a hyperactive antifreeze protein from the beetle Dendroides canadensis (DAFP-1) using vibrational sum-frequency generation spectroscopy. We find that DAFP-1 accumulates at the air-water interface due to the hydrophobic character of its threonine-rich IBS while retaining its highly regular β-helical fold. We observe a narrow band at 3485 cm(-1) that we assign to the O-H stretch vibration of threonine hydroxyl groups of the IBS. The narrow character of the 3485 cm(-1) band suggests that the hydrogen bonds between the threonine residues at the IBS and adjacent water molecules are quite similar in strength, indicating that the IBS of DAFP-1 is extremely well-ordered, with the threonine side chains showing identical rotameric confirmations. The hydrogen-bonded water molecules do not form an ordered ice-like layer, as was recently observed for the moderate antifreeze protein type III. It thus appears that the antifreeze action of DAFP-1 does not require the presence of ordered water but likely results from the direct binding of its highly ordered array of threonine residues to the ice surface.
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Affiliation(s)
- Konrad Meister
- †FOM-Institute for Atomic and Molecular Physics AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Stephan Lotze
- †FOM-Institute for Atomic and Molecular Physics AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Luuk L C Olijve
- ‡Laboratory of Macromolecular and Organic Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
| | - Arthur L DeVries
- §Department of Animal Biology, University of Illinois at Urbana-Champaign, 515 Morrill Hall, Urbana, Illinois 61801, United States
| | - John G Duman
- ∥Department of Biological Sciences, University of Notre Dame, 100 Galvin Life Sciences Center, Notre Dame, Indiana 46556, United States
| | - Ilja K Voets
- ‡Laboratory of Macromolecular and Organic Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
| | - Huib J Bakker
- †FOM-Institute for Atomic and Molecular Physics AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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Gochev G. Thin liquid films stabilized by polymers and polymer/surfactant mixtures. Curr Opin Colloid Interface Sci 2015. [DOI: 10.1016/j.cocis.2015.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
We study the properties of water at the surface of an antifreeze protein with femtosecond surface sum frequency generation spectroscopy. We find clear evidence for the presence of ice-like water layers at the ice-binding site of the protein in aqueous solution at temperatures above the freezing point. Decreasing the temperature to the biological working temperature of the protein (0 °C to -2 °C) increases the amount of ice-like water, while a single point mutation in the ice-binding site is observed to completely disrupt the ice-like character and to eliminate antifreeze activity. Our observations indicate that not the protein itself but ordered ice-like water layers are responsible for the recognition and binding to ice.
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Lech FJ, Steltenpool P, Meinders MB, Sforza S, Gruppen H, Wierenga PA. Identifying changes in chemical, interfacial and foam properties of β-lactoglobulin–sodium dodecyl sulphate mixtures. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.08.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lotfi M, Karbaschi M, Javadi A, Mucic N, Krägel J, Kovalchuk V, Rubio R, Fainerman V, Miller R. Dynamics of liquid interfaces under various types of external perturbations. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2014.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Engelhardt K, Weichsel U, Kraft E, Segets D, Peukert W, Braunschweig B. Mixed Layers of β-Lactoglobulin and SDS at Air–Water Interfaces with Tunable Intermolecular Interactions. J Phys Chem B 2014; 118:4098-105. [DOI: 10.1021/jp501541q] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Kathrin Engelhardt
- Institute of Particle Technology
(LFG), University of Erlangen-Nuremberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Ulrike Weichsel
- Institute of Particle Technology
(LFG), University of Erlangen-Nuremberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Elena Kraft
- Institute of Particle Technology
(LFG), University of Erlangen-Nuremberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Doris Segets
- Institute of Particle Technology
(LFG), University of Erlangen-Nuremberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology
(LFG), University of Erlangen-Nuremberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Björn Braunschweig
- Institute of Particle Technology
(LFG), University of Erlangen-Nuremberg, Cauerstrasse 4, 91058 Erlangen, Germany
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