1
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Stachurska K, Marcisz U, Długosz M, Antosiewicz JM. Kinetics of Structural Transitions Induced by Sodium Dodecyl Sulfate in α-Chymotrypsin. ACS OMEGA 2023; 8:49137-49149. [PMID: 38162786 PMCID: PMC10753550 DOI: 10.1021/acsomega.3c07256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/16/2023] [Accepted: 11/23/2023] [Indexed: 01/03/2024]
Abstract
The temporal changes in circular dichroism at 222 and 260 nm were recorded by using stopped-flow spectroscopy after mixing α-chymotrypsin solutions with sodium dodecyl sulfate solutions. Simultaneously with the circular dichroism signal, the fluorescence emission was recorded. Changes in the secondary and tertiary structures of chymotrypsin induced by sodium dodecyl sulfate are characterized by either three or four one-way reactions with relaxation amplitudes and times precisely determined by an advanced numerical procedure of Kuzmič. Quantitatively, transitions within the secondary and tertiary structures of the protein are significantly different. Moreover, changes in the tertiary structure depend on the type of recorded signal (either circular dichroism or fluorescence) and the wavelength of the incident radiation. The latter observation is particularly interesting as it indicates that the contributions of protein's different tryptophans to the total recorded fluorescence depend on the excitation wavelength. We present several results justifying this hypothesis.
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Affiliation(s)
- Karolina Stachurska
- Biophysics Division, Institute of Experimental
Physics, Faculty of Physics, University
of Warsaw, Pasteura 5 Street, 02-093 Warsaw, Poland
| | - Urszula Marcisz
- Biophysics Division, Institute of Experimental
Physics, Faculty of Physics, University
of Warsaw, Pasteura 5 Street, 02-093 Warsaw, Poland
| | - Maciej Długosz
- Biophysics Division, Institute of Experimental
Physics, Faculty of Physics, University
of Warsaw, Pasteura 5 Street, 02-093 Warsaw, Poland
| | - Jan M. Antosiewicz
- Biophysics Division, Institute of Experimental
Physics, Faculty of Physics, University
of Warsaw, Pasteura 5 Street, 02-093 Warsaw, Poland
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2
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Sun Y, Oseliero Filho PL, Song Y, Wang Z, Ji H, Oliveira CLP. The role of hydrophobic interactions in the molten globule state of globular protein modulated by surfactants. Colloids Surf B Biointerfaces 2023; 230:113490. [PMID: 37556880 DOI: 10.1016/j.colsurfb.2023.113490] [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: 04/26/2023] [Revised: 06/25/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023]
Abstract
In order to highlight the role of hydrophobic interactions in the molten globule (MG) state of globular protein modulated by surfactants, the interactions of bovine α-lactalbumin (α-LA) with alkyl trimethylammonium bromides (CnTAB, n = 10, 12, 14, and 16) have been studied by experimental and theoretical techniques. Isothermal titration calorimetry (ITC) showed that the enthalpy changes (ΔH) and area of the enthalpogram increased with increasing the chain length of CnTAB. The result of fluorescence, circular dichroism (CD) and 1H nuclear magnetic resonance (NMR) spectrum suggested that C10TAB and C12TAB unfolded α-LA partially, C14TAB reconstructed protein with a native-like secondary structure content, and C16TAB induced an MG state α-LA. The SAXS results confirmed that the tertiary structure of α-LA was disrupted by C16TAB forming an MG state complex with a micelle-like structure even at the surfactants concentrations below CMC. As indicated by MD results, the β-domain and unstructured region(s) were involved in the MG state α-LA modulated by CnTAB. This work not only provides molecular insights into the role of hydrophobic interactions in the MG state of a globular protein but also helps understand the mechanism of preparing α-LA based biomacromolecule modulated by hydrophobic interactions.
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Affiliation(s)
- Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China.
| | | | - Yang Song
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Zhichun Wang
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Hang Ji
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
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3
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Otzen DE, Pedersen JN, Rasmussen HØ, Pedersen JS. How do surfactants unfold and refold proteins? Adv Colloid Interface Sci 2022; 308:102754. [PMID: 36027673 DOI: 10.1016/j.cis.2022.102754] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/25/2022] [Accepted: 08/10/2022] [Indexed: 11/01/2022]
Abstract
Although the anionic surfactant sodium dodecyl sulfate, SDS, has been used for more than half a century as a versatile and efficient protein denaturant for protein separation and size estimation, there is still controversy about its mode of interaction with proteins. The term "rod-like" structures for the complexes that form between SDS and protein, originally introduced by Tanford, is not sufficiently descriptive and does not distinguish between the two current vying models, namely protein-decorated micelles a.k.a. the core-shell model (in which denatured protein covers the surface of micelles) versus beads-on-a-string model (where unfolded proteins are surrounded by surfactant micelles). Thanks to a combination of structural, kinetic and computational work particularly within the last 5-10 years, it is now possible to rule decisively in favor of the core-shell model. This is supported unambiguously by a combination of calorimetric and small-angle X-ray scattering (SAXS) techniques and confirmed by increasingly sophisticated molecular dynamics simulations. Depending on the SDS:protein ratio and the protein molecular mass, the formed structures can range from multiple partly unfolded protein molecules surrounding a single shared micelle to a single polypeptide chain decorating multiple micelles. We also have much new insight into how this species forms. It is preceded by the binding of small numbers of SDS molecules which subsequently grow by accretion. Time-resolved SAXS analysis reveals an asymmetric attack by SDS micelles followed by distribution of the increasingly unfolded protein around the micelle. The compactness of the protein chain continues to evolve at higher SDS concentrations according to single-molecule studies, though the protein remains completely denatured on the tertiary structural level. SDS denaturation can be reversed by addition of nonionic surfactants that absorb SDS forming mixed micelles, leaving the protein free to refold. Refolding can occur in parallel tracks if only a fraction of the protein is initially stripped of SDS. SDS unfolding is nearly always reversible unless carried out at low pH, where charge neutralization can lead to superclusters of protein-surfactant complexes. With the general mechanism of SDS denaturation now firmly established, it largely remains to explore how other ionic surfactants (including biosurfactants) may diverge from this path.
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Affiliation(s)
- Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C, Denmark.
| | - Jannik Nedergaard Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Helena Østergaard Rasmussen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
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4
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Wibel R, Knoll P, Le-Vinh B, Kali G, Bernkop-Schnürch A. Synthesis and evaluation of sulfosuccinate-based surfactants as counterions for hydrophobic ion pairing. Acta Biomater 2022; 144:54-66. [PMID: 35292415 DOI: 10.1016/j.actbio.2022.03.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/08/2022] [Accepted: 03/07/2022] [Indexed: 11/26/2022]
Abstract
Hydrophobic ion pairing is a promising strategy to raise the lipophilic character of therapeutic peptides and proteins. In past studies, docusate, an all-purpose surfactant with a dialkyl sulfosuccinate structure, showed highest potential as hydrophobic counterion. Being originally not purposed for hydrophobic ion pairing, it is likely still far away from the perfect counterion. Thus, within this study, docusate analogues with various linear and branched alkyl residues were synthesized to derive systematic insights into which hydrophobic tail is most advantageous for hydrophobic ion pairing, as well as to identify lead counterions that form complexes with superior hydrophobicity. The successful synthesis of the target compounds was confirmed by FT-IR, 1H-NMR, and 13C-NMR. In a screening with the model protein hemoglobin, monostearyl sulfosuccinate, dioleyl sulfosuccinate, and bis(isotridecyl) sulfosuccinate were identified as lead counterions. Their potential was further evaluated with the peptides and proteins vancomycin, insulin, and horseradish peroxidase. Dioleyl sulfosuccinate and bis(isotridecyl) sulfosuccinate significantly increased the hydrophobicity of the tested peptides and proteins determined as logP or lipophilicity determined as solubility in 1-octanol, respectively, in comparison to the gold standard docusate. Dioleyl sulfosuccinate provided an up to 8.3-fold higher partition coefficient and up to 26.5-fold higher solubility in 1-octanol than docusate, whereas bis(isotridecyl) sulfosuccinate resulted in an up to 6.7-fold improvement in the partition coefficient and up to 44.0-fold higher solubility in 1-octanol. The conjugation of highly lipophilic alkyl tails to the polar sulfosuccinate head group allows the design of promising counterions for hydrophobic ion pairing. STATEMENT OF SIGNIFICANCE: Hydrophobic ion pairing enables efficient incorporation of hydrophilic molecules into lipid-based formulations by forming complexes with hydrophobic counterions. Docusate, a sulfosuccinate with two branched alkyl tails, has shown highest potential as anionic hydrophobic counterion. As it was originally not purposed for hydrophobic ion pairing, its structure is likely still far away from the perfect counterion. To improve its properties, analogues of docusate with various alkyl tails were synthesized in the present study. The investigation of different alkyl residues allowed to derive systematic insights into which tail structures are most favorable for hydrophobic ion pairing. Moreover, the lead counterions dioleyl sulfosuccinate and bis(isotridecyl) sulfosuccinate bearing highly lipophilic alkyl tails provided a significant improvement in the hydrophobicity of the resulting complexes.
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5
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Fatma I, Sharma V, Thakur RC, Kumar A. Current trends in protein-surfactant interactions: A review. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117344] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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6
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Mortensen HG, Otzen DE, Pedersen JS. Ubiquitin forms conventional decorated micelle structures with sodium dodecyl sulfate at saturation. J Colloid Interface Sci 2021; 596:233-244. [DOI: 10.1016/j.jcis.2021.03.110] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/10/2021] [Accepted: 03/19/2021] [Indexed: 12/20/2022]
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7
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Sanchez-Fernandez A, Diehl C, Houston JE, Leung AE, Tellam JP, Rogers SE, Prevost S, Ulvenlund S, Sjögren H, Wahlgren M. An integrative toolbox to unlock the structure and dynamics of protein-surfactant complexes. NANOSCALE ADVANCES 2020; 2:4011-4023. [PMID: 36132802 PMCID: PMC9417085 DOI: 10.1039/d0na00194e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 07/11/2020] [Indexed: 05/06/2023]
Abstract
The interactions between protein and surfactants play an important role in the stability and performance of formulated products. Due to the high complexity of such interactions, multi-technique approaches are required to study these systems. Here, an integrative approach is used to investigate the various interactions in a model system composed of human growth hormone and sodium dodecyl sulfate. Contrast variation small-angle neutron scattering was used to obtain information on the structure of the protein, surfactant aggregates and surfactant-protein complexes. 1H and 1H-13C HSQC nuclear magnetic resonance spectroscopy was employed to probe the local structure and dynamics of specific amino acids upon surfactant addition. Through the combination of these advanced methods with fluorescence spectroscopy, circular dichroism and isothermal titration calorimetry, it was possible to identify the interaction mechanisms between the surfactant and the protein in the pre- and post-micellar regimes, and interconnect the results from different techniques. As such, the protein was revealed to evolve from a partially unfolded conformation at low SDS concentration to a molten globule at intermediate concentrations, where the protein conformation and local dynamics of hydrophobic amino acids are partially affected compared to the native state. At higher surfactant concentrations the local structure of the protein appears disrupted, and a decorated micelle structure is observed, where the protein is wrapped around a surfactant assembly. Importantly, this integrative approach allows for the identification of the characteristic fingerprints of complex transitions as seen by each technique, and establishes a methodology for an in-detail study of surfactant-protein systems.
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Affiliation(s)
| | - Carl Diehl
- SARomics Biostructures AB Medicon Village, Scheelevägen 2 223 81 Lund Sweden
| | | | - Anna E Leung
- European Spallation Source Box 176 221 00 Lund Sweden
| | - James P Tellam
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Didcot OX11 0QX UK
| | - Sarah E Rogers
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Didcot OX11 0QX UK
| | - Sylvain Prevost
- Institut Laue-Langevin 71 Avenue des Martyrs 38000 Grenoble France
| | - Stefan Ulvenlund
- Food Technology, Engineering and Nutrition, Lund University Box 124 221 00 Lund Sweden
- EnzaBiotech AB Scheelevägen 22 223 63 Lund Sweden
| | - Helen Sjögren
- Ferring Pharmaceuticals A/S Kay Fiskers Plads 11 2300 Copenhagen S Denmark
| | - Marie Wahlgren
- Food Technology, Engineering and Nutrition, Lund University Box 124 221 00 Lund Sweden
- EnzaBiotech AB Scheelevägen 22 223 63 Lund Sweden
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8
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Enhancement of covalent aggregate quantification of protein therapeutics by non-reducing capillary gel electrophoresis using sodium hexadecyl sulfate (CE-SHS). J Chromatogr B Analyt Technol Biomed Life Sci 2020; 1152:122230. [DOI: 10.1016/j.jchromb.2020.122230] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 04/30/2020] [Accepted: 06/08/2020] [Indexed: 12/27/2022]
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9
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Cao F, Xia Y, Chen D, Xu N, Hemar Y, Li N, Sun Y. Insights on the structure of caseinate particles based on surfactants-induced dissociation. Food Hydrocoll 2020. [DOI: 10.1016/j.foodhyd.2020.105766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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10
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Poghosyan AH, Schafer NP, Lyngsø J, Shahinyan AA, Pedersen JS, Otzen DE. Molecular dynamics study of ACBP denaturation in alkyl sulfates demonstrates possible pathways of unfolding through fused surfactant clusters. Protein Eng Des Sel 2019; 32:175-190. [DOI: 10.1093/protein/gzz037] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 08/20/2019] [Accepted: 08/28/2019] [Indexed: 11/15/2022] Open
Abstract
AbstractAnionic surfactants denature proteins at low millimolar concentrations, yet little is known about the underlying molecular mechanisms. Here, we undertake 1-μs-long atomistic molecular dynamics simulations of the denaturation of acyl coenzyme A binding protein (ACBP) and compare our results with previously published and new experimental data. Since increasing surfactant chain length is known to lead to more rapid denaturation, we studied denaturation using both the medium-length alkyl chain surfactant sodium dodecyl sulfate (SDS) and the long alkyl chain surfactant sodium hexadecyl sulfate (SHS). In silico denaturation on the microsecond timescale was not achieved using preformed surfactant micelles but required ACBP to be exposed to monomeric surfactant molecules. Micellar self-assembly occurred together with protein denaturation. To validate our analyses, we calculated small-angle X-ray scattering spectra of snapshots from the simulations. These agreed well with experimental equilibrium spectra recorded on ACBP-SDS mixtures with similar compositions. Protein denaturation occurs through the binding of partial micelles to multiple preferred binding sites followed by the accretion of surfactant monomers until these partial micelles merge to form a mature micelle and the protein chain is left disordered on the surface of the micelle. While the two surfactants attack in a similar fashion, SHS’s longer alkyl chain leads to a more efficient denaturation through the formation of larger clusters that attack ACBP, a more rapid drop in native contacts, a greater expansion in size, as well as a more thorough rearrangement of hydrogen bonds and disruption of helices.
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Affiliation(s)
- Armen H Poghosyan
- International Scientific-Educational Center of National Academy of Sciences of Armenia, 24d Marshal Baghramyan Ave, Yerevan 0019, Armenia
| | - Nicholas P Schafer
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus, Denmark
- Center for Theoretical Biological Physics, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Jeppe Lyngsø
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
- Department of Chemistry, Aarhus University, Langelandsgade 120, 8000 Aarhus, Denmark
| | - Aram A Shahinyan
- International Scientific-Educational Center of National Academy of Sciences of Armenia, 24d Marshal Baghramyan Ave, Yerevan 0019, Armenia
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
- Department of Chemistry, Aarhus University, Langelandsgade 120, 8000 Aarhus, Denmark
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus, Denmark
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11
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Højgaard C, Sørensen HV, Pedersen JS, Winther JR, Otzen DE. Can a Charged Surfactant Unfold an Uncharged Protein? Biophys J 2018; 115:2081-2086. [PMID: 30447995 DOI: 10.1016/j.bpj.2018.10.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/05/2018] [Accepted: 10/24/2018] [Indexed: 11/26/2022] Open
Abstract
Does sodium dodecyl sulfate (SDS) denature proteins through electrostatic SDS-protein interactions? We show that a protein completely lacking charged side chains is unfolded by SDS in a manner similar to charged proteins, revealing that formal protein charges are not required for SDS-induced protein unfolding or binding.
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Affiliation(s)
- Casper Højgaard
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Jan Skov Pedersen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Jakob Rahr Winther
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Daniel Erik Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark.
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12
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Ferreira GMD, Ferreira GMD, Agudelo ÁJP, Hudson EA, Pires ACDS, da Silva LHM. Lactoferrin denaturation induced by anionic surfactants: The role of the ferric ion in the protein stabilization. Int J Biol Macromol 2018; 117:1039-1049. [DOI: 10.1016/j.ijbiomac.2018.05.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/19/2022]
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13
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Andersen KK, Vad BS, Kjær L, Tolker‐Nielsen T, Christiansen G, Otzen DE. Pseudomonas aeruginosa
rhamnolipid induces fibrillation of human α‐synuclein and modulates its effect on biofilm formation. FEBS Lett 2018; 592:1484-1496. [DOI: 10.1002/1873-3468.13038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/21/2018] [Accepted: 03/12/2018] [Indexed: 01/20/2023]
Affiliation(s)
- Kell K. Andersen
- Interdisciplinary Nanoscience Center (iNANO) Department of Molecular Biology and Genetics Aarhus University Denmark
| | - Brian S. Vad
- Interdisciplinary Nanoscience Center (iNANO) Department of Molecular Biology and Genetics Aarhus University Denmark
| | - Lars Kjær
- Interdisciplinary Nanoscience Center (iNANO) Department of Molecular Biology and Genetics Aarhus University Denmark
| | - Tim Tolker‐Nielsen
- Costerton Biofilm Center Department of Immunology and Microbiology University of Copenhagen Denmark
| | | | - Daniel E. Otzen
- Interdisciplinary Nanoscience Center (iNANO) Department of Molecular Biology and Genetics Aarhus University Denmark
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14
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Gehlot P, Kulshrestha A, Bharmoria P, Damarla K, Chokshi K, Kumar A. Surface-Active Ionic Liquid Cholinium Dodecylbenzenesulfonate: Self-Assembling Behavior and Interaction with Cellulase. ACS OMEGA 2017; 2:7451-7460. [PMID: 31457311 PMCID: PMC6644741 DOI: 10.1021/acsomega.7b01291] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Accepted: 10/17/2017] [Indexed: 06/10/2023]
Abstract
The conventional sodium dodecylbenzenesulfonate (NaDBS) has been converted into an efficient and nontoxic anionic surface-active ionic liquid, cholinium dodecylbenzenesulfonate (Cho[DBS]). We have investigated its self-assembling behavior, interaction with the enzyme cellulase, and ecotoxicity. The surface-active properties at the air-liquid interface and the aggregation behavior of Cho[DBS] in water have been determined using tensiometry, isothermal titration calorimetry (ITC), conductometry, and dynamic light scattering (DLS). The enzyme activity was observed using dinitro salicylic acid analysis. The enhanced enzyme activity was explained through active-site exfoliation and structural constancy of cellulase in the micellar medium using the results from fluorescence, circular dichroism, DLS, and ITC. The nontoxic nature was confirmed by toxicity analysis on the freshwater microalgae Scenedesmus sp.
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Affiliation(s)
- Praveen
Singh Gehlot
- Academy
of Scientific and Innovative Research (AcSIR), Salt and Marine
Chemicals Discipline, and Salt and Marine Chemicals Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India
| | - Akshay Kulshrestha
- Academy
of Scientific and Innovative Research (AcSIR), Salt and Marine
Chemicals Discipline, and Salt and Marine Chemicals Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India
| | - Pankaj Bharmoria
- Academy
of Scientific and Innovative Research (AcSIR), Salt and Marine
Chemicals Discipline, and Salt and Marine Chemicals Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India
| | - Krishnaiah Damarla
- Academy
of Scientific and Innovative Research (AcSIR), Salt and Marine
Chemicals Discipline, and Salt and Marine Chemicals Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India
| | - Kaumeel Chokshi
- Academy
of Scientific and Innovative Research (AcSIR), Salt and Marine
Chemicals Discipline, and Salt and Marine Chemicals Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India
| | - Arvind Kumar
- Academy
of Scientific and Innovative Research (AcSIR), Salt and Marine
Chemicals Discipline, and Salt and Marine Chemicals Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364002, Gujarat, India
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15
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Liguori L, Stidder B, Alcaraz JP, Lenormand JL, Cinquin P, Martin DK. Cell-free production of VDAC directly into liposomes for integration with biomimetic membrane systems. Prep Biochem Biotechnol 2017; 46:546-51. [PMID: 26443900 DOI: 10.1080/10826068.2015.1068800] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mitochondrial voltage-dependent anion channel (VDAC) is a pivotal protein since it provides the major transport pathway between the cytosol and the mitochondrial intermembrane space and it is implicated in cell apoptosis by functioning as a gatekeeper for the trafficking of mitochondrial death molecules. VDAC is a beta-barrel channel with a large conductance, and we use it as a model transport protein for the design of biomimetic systems. To overcome the limitations of classical overexpression methods for producing and purifying membrane proteins (MPs) we describe here the use of an optimized cell-free system. In a one-step reaction VDAC is obtained directly integrated into liposomes and purified by ultracentrifugation. We then combine proteoliposomes with different bilayers models in order to validate VDAC insertion and functionality. This VDAC biomimetic model is the first example validating the use of a cell-free expression system for production of MPs into liposomes and tethered bilayers as a toolbox to build a wide range of biomimetic devices.
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Affiliation(s)
- Lavinia Liguori
- a University of Grenoble 1-Joseph Fourier/CNRS/TIMC-IMAG UMR 5525 (Equipe SyNaBi) , Grenoble , France
| | - Barry Stidder
- a University of Grenoble 1-Joseph Fourier/CNRS/TIMC-IMAG UMR 5525 (Equipe SyNaBi) , Grenoble , France
| | - Jean-Pierre Alcaraz
- a University of Grenoble 1-Joseph Fourier/CNRS/TIMC-IMAG UMR 5525 (Equipe SyNaBi) , Grenoble , France
| | - Jean-Luc Lenormand
- a University of Grenoble 1-Joseph Fourier/CNRS/TIMC-IMAG UMR 5525 (Equipe SyNaBi) , Grenoble , France
| | - Philippe Cinquin
- a University of Grenoble 1-Joseph Fourier/CNRS/TIMC-IMAG UMR 5525 (Equipe SyNaBi) , Grenoble , France
| | - Donald K Martin
- a University of Grenoble 1-Joseph Fourier/CNRS/TIMC-IMAG UMR 5525 (Equipe SyNaBi) , Grenoble , France
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16
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Patra A, Samanta N, Das DK, Mitra RK. Enhanced Catalytic Activity of α-Chymotrypsin in Cationic Surfactant Solutions: The Component Specificity Revisited. J Phys Chem B 2017; 121:1457-1465. [PMID: 28151666 DOI: 10.1021/acs.jpcb.6b10472] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enhanced catalytic activity (super activity) of enzymes in the presence of surfactants is of key importance in "micellar enzymology"; such super activity is not very trivial, it is highly system specific, and the mechanism behind the activity enhancement is not always well apprehended. We report the catalytic activity of α-chymotrypsin (CHT) on ala-ala-phe-7-amido-4-methylcoumarin (AMC) in the presence of cationic surfactants of different hydrophobic chain lengths: dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and octadecyltrimethylammonium bromide (OTAB). It is observed that in comparison to buffer the catalytic activity of CHT is enhanced 5-fold in premicellar DTAB solutions, while negligible changes are observed in CTAB and OTAB. Activity decreases considerably in the post micellar concentration, specifically for the latter two surfactants. A similar trend is also obtained in another substrate 2-napthyal acetate hydrolysis. Such surfactant specific superactivity is intriguing. The protein's secondary and tertiary structures in the presence of these surfactants are determined using circular dichroism (CD) spectroscopy and it is found that both CTAB and OTAB perturb the protein structure significantly, especially in the post micellar concentrations. DTAB, on the other hand, does not produce noticeable changes in the protein structure. The various pairwise interactions present in the system have been underlined using both steady-state and time-resolved fluorescence spectroscopy. Assuming a three-step kinetics model, we determine the free energy changes of the reaction, and the observations have been discussed in the light of the various interactions among the components.
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Affiliation(s)
- Animesh Patra
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Nirnay Samanta
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Dipak Kumar Das
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Rajib Kumar Mitra
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700106, India
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17
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Andersen KK, Vad BS, Scavenius C, Enghild JJ, Otzen DE. Human Lysozyme Peptidase Resistance Is Perturbed by the Anionic Glycolipid Biosurfactant Rhamnolipid Produced by the Opportunistic Pathogen Pseudomonas aeruginosa. Biochemistry 2016; 56:260-270. [DOI: 10.1021/acs.biochem.6b01009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Kell K. Andersen
- Interdisciplinary Nanoscience Center (iNANO),
Department of Molecular Biology and Genetics, Aarhus University, Gustav
Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Brian S. Vad
- Interdisciplinary Nanoscience Center (iNANO),
Department of Molecular Biology and Genetics, Aarhus University, Gustav
Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Carsten Scavenius
- Interdisciplinary Nanoscience Center (iNANO),
Department of Molecular Biology and Genetics, Aarhus University, Gustav
Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Jan J. Enghild
- Interdisciplinary Nanoscience Center (iNANO),
Department of Molecular Biology and Genetics, Aarhus University, Gustav
Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Daniel E. Otzen
- Interdisciplinary Nanoscience Center (iNANO),
Department of Molecular Biology and Genetics, Aarhus University, Gustav
Wieds Vej 14, DK-8000 Aarhus C, Denmark
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18
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Mehan S, Aswal VK, Kohlbrecher J. Tuning of protein-surfactant interaction to modify the resultant structure. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032713. [PMID: 26465504 DOI: 10.1103/physreve.92.032713] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Indexed: 06/05/2023]
Abstract
Small-angle neutron scattering and dynamic light scattering studies have been carried out to examine the interaction of bovine serum albumin (BSA) protein with different surfactants under varying solution conditions. We show that the interaction of anionic BSA protein (pH7) with surfactant and the resultant structure are strongly modified by the charge head group of the surfactant, ionic strength of the solution, and mixed surfactants. The protein-surfactant interaction is maximum when two components are oppositely charged, followed by components being similarly charged through the site-specific binding, and no interaction in the case of a nonionic surfactant. This interaction of protein with ionic surfactants is characterized by the fractal structure representing a bead-necklace structure of micellelike clusters adsorbed along the unfolded protein chain. The interaction is enhanced with ionic strength only in the case of site-specific binding of an anionic surfactant with an anionic protein, whereas it is almost unchanged for other complexes of cationic and nonionic surfactants with anionic proteins. Interestingly, the interaction of BSA protein with ionic surfactants is significantly suppressed in the presence of nonionic surfactant. These results with mixed surfactants thus can be used to fold back the unfolded protein as well as to prevent surfactant-induced protein unfolding. For different solution conditions, the results are interpreted in terms of a change in fractal dimension, the overall size of the protein-surfactant complex, and the number of micelles attached to the protein. The interplay of electrostatic and hydrophobic interactions is found to govern the resultant structure of complexes.
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Affiliation(s)
- Sumit Mehan
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Vinod K Aswal
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Joachim Kohlbrecher
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen, Switzerland
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19
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20
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Madsen JK, Pihl R, Møller AH, Madsen AT, Otzen DE, Andersen KK. The anionic biosurfactant rhamnolipid does not denature industrial enzymes. Front Microbiol 2015; 6:292. [PMID: 25941516 PMCID: PMC4400916 DOI: 10.3389/fmicb.2015.00292] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/24/2015] [Indexed: 11/13/2022] Open
Abstract
Biosurfactants (BS) are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL) and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS) on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ), the phospholipase Lecitase Ultra® (LT) and the α-amylase Stainzyme® (SZ). Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction toward the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the enzyme well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries) to SZ. Furthermore, all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant enzymes. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.
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Affiliation(s)
| | | | | | | | - Daniel E. Otzen
- Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
| | - Kell K. Andersen
- Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
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21
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Andersen KK, Otzen DE. Denaturation of α-lactalbumin and myoglobin by the anionic biosurfactant rhamnolipid. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:2338-45. [DOI: 10.1016/j.bbapap.2014.10.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 09/30/2014] [Accepted: 10/07/2014] [Indexed: 11/26/2022]
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22
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Andersen KK, Otzen DE. Folding of outer membrane protein A in the anionic biosurfactant rhamnolipid. FEBS Lett 2014; 588:1955-60. [PMID: 24735722 DOI: 10.1016/j.febslet.2014.04.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 03/21/2014] [Accepted: 04/02/2014] [Indexed: 01/11/2023]
Abstract
Folding and stability of bacterial outer membrane proteins (OMPs) are typically studied in vitro using model systems such as phospholipid vesicles or surfactant. OMP folding requires surfactant concentrations above the critical micelle concentration (cmc) and usually only occurs in neutral or zwitterionic surfactants, but not in anionic or cationic surfactants. Various Gram-negative bacteria produce the anionic biosurfactant rhamnolipid. Here we show that the OMP OmpA can be folded in rhamnolipid at concentrations above the cmc, though the thermal stability is reduced compared to the non-ionic surfactant dodecyl maltoside. We discuss implications for possible interactions between OMPs and biosurfactants in vivo.
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Affiliation(s)
- Kell K Andersen
- iNANO, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK - 8000 Aarhus C, Denmark.
| | - Daniel E Otzen
- iNANO, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK - 8000 Aarhus C, Denmark.
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23
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Nieto-Ortega B, Hierrezuelo JM, Carnero Ruiz C, López Navarrete JT, Casado J, Ramírez FJ. Unfolding Pathway of a Globular Protein by Surfactants Monitored with Raman Optical Activity. J Phys Chem Lett 2014; 5:8-13. [PMID: 26276173 DOI: 10.1021/jz402291s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Protein denaturation by surfactants has received increased attention in the last years due to its implications in topics such as pharmaceutics, cosmetics, paints, or biotechnology. This phenomenon is highly dependent on the physicochemical (structural) properties of the denaturing agents. In this work, we have measured for the first time the Raman optical activity (ROA) of bovine serum albumin (BSA) in the presence of three surfactants (anionic, cationic, and neutral), which has allowed us to detect new spectroscopic insights of the protein-surfactant interaction that conventional Raman spectroscopy cannot. Our work proposes two new groups of ROA marker bands to explore the unfolding of BSA induced by surfactants, which are related to "polar" (amide I and III modes) and "apolar" (methylene bending and phenyl breathing modes) protein sections. The appearance of the former groups is related to the initial attack of the surfactant, while the second groups relate to the hydrophobic unfolding.
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Affiliation(s)
- Belén Nieto-Ortega
- †Department of Physical Chemistry, Faculty of Sciences and ‡Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga, Spain
| | - José M Hierrezuelo
- †Department of Physical Chemistry, Faculty of Sciences and ‡Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga, Spain
| | - Cristóbal Carnero Ruiz
- †Department of Physical Chemistry, Faculty of Sciences and ‡Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga, Spain
| | - Juan Teodomiro López Navarrete
- †Department of Physical Chemistry, Faculty of Sciences and ‡Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga, Spain
| | - Juan Casado
- †Department of Physical Chemistry, Faculty of Sciences and ‡Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga, Spain
| | - Francisco J Ramírez
- †Department of Physical Chemistry, Faculty of Sciences and ‡Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga, Spain
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24
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Mehan S, Chinchalikar AJ, Kumar S, Aswal VK, Schweins R. Small-angle neutron scattering study of structure and interaction of nanoparticle, protein, and surfactant complexes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11290-11299. [PMID: 23968136 DOI: 10.1021/la402977b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Small-angle neutron scattering (SANS) measurements have been carried out from the multicomponent system composed of Ludox HS40 silica nanoparticle, bovine serum albumin (BSA) protein, and sodium dodecyl sulfate (SDS) surfactant in an aqueous system under the solution condition that all the components are negatively charged. Although the components are similarly charged, strong structural evolutions among them have been observed. The complexes of different components in pairs (nanoparticle-protein, nanoparticle-surfactant, and protein-surfactant) have been examined to correlate the role of each component in the three-component nanoparticle-protein-surfactant system. The nanoparticle-protein system shows depletion interaction induced aggregation of nanoparticles in the presence of protein. Both nanoparticle and surfactant coexist individually in a nanoparticle-surfactant system. In the case of a protein-surfactant system, the cooperative binding of surfactant with protein leads to micelle-like clusters of surfactant formed along the unfolded protein chain. The structure of the three-component (nanoparticle-protein-surfactant) system is found to be governed by the synergetic effect of nanoparticle-protein and protein-surfactant interactions. The nanoparticle aggregates coexist with the structures of protein-surfactant complex in the three-component system. The nanoparticle aggregation as well as unfolding of protein is enhanced in this system as compared to the corresponding two-component systems.
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Affiliation(s)
- Sumit Mehan
- Solid State Physics Division, Bhabha Atomic Research Centre , Mumbai 400 085, India
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25
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Morgner N, Montenegro F, Barrera NP, Robinson CV. Mass spectrometry--from peripheral proteins to membrane motors. J Mol Biol 2012; 423:1-13. [PMID: 22750574 PMCID: PMC4058634 DOI: 10.1016/j.jmb.2012.06.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 06/18/2012] [Accepted: 06/20/2012] [Indexed: 10/28/2022]
Abstract
That membrane protein complexes could survive in the gas phase had always seemed impossible. The lack of chargeable residues, high hydrophobicity, and poor solubility and the vast excess of detergent contributed to the view that it would not be possible to obtain mass spectra of intact membrane complexes. With the recent success in recording mass spectra of these complexes, first from recombinant sources and later from the cellular environment, many surprising properties of these gas phase membrane complexes have been revealed. The first of these was that the interactions between membrane and soluble subunits could survive in vacuum, without detergent molecules adhering to the complex. The second unexpected feature was that their hydrophobicity and, consequently, lower charge state did not preclude ionization. The final surprising finding was that these gas phase membrane complexes carry with them lipids, bound specifically in subunit interfaces. This provides us with an opportunity to distinguish annular lipids that surround the membrane complexes, from structural lipids that have a role in maintaining structure and subunit interactions. In this perspective, we track these developments and suggest explanations for the various discoveries made during this research.
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Affiliation(s)
- Nina Morgner
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
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26
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Andersen KK, Wang H, Otzen DE. A Kinetic Analysis of the Folding and Unfolding of OmpA in Urea and Guanidinium Chloride: Single and Parallel Pathways. Biochemistry 2012; 51:8371-83. [DOI: 10.1021/bi300974y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kell K. Andersen
- Interdisciplinary Nanoscience Centre (iNANO), Centre
for Insoluble Protein Structures (inSPIN), Department of Molecular
Biology and Genetics, University of Aarhus, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Huabing Wang
- Interdisciplinary Nanoscience Centre (iNANO), Centre
for Insoluble Protein Structures (inSPIN), Department of Molecular
Biology and Genetics, University of Aarhus, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Daniel E. Otzen
- Interdisciplinary Nanoscience Centre (iNANO), Centre
for Insoluble Protein Structures (inSPIN), Department of Molecular
Biology and Genetics, University of Aarhus, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
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27
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Otzen D. Protein–surfactant interactions: A tale of many states. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:562-91. [DOI: 10.1016/j.bbapap.2011.03.003] [Citation(s) in RCA: 362] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 02/23/2011] [Accepted: 03/04/2011] [Indexed: 10/18/2022]
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28
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Hansted JG, Wejse PL, Bertelsen H, Otzen DE. Effect of protein-surfactant interactions on aggregation of β-lactoglobulin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:713-23. [PMID: 21440683 DOI: 10.1016/j.bbapap.2011.03.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/16/2011] [Accepted: 03/17/2011] [Indexed: 11/26/2022]
Abstract
The milk protein β-lactoglobulin (βLG) dominates the properties of whey aggregates in food products. Here we use spectroscopic and calorimetric techniques to elucidate how anionic, cationic and non-ionic surfactants interact with bovine βLG and modulate its heat-induced aggregation. Alkyl trimethyl ammonium chlorides (xTAC) strongly promote aggregation, while sodium alkyl sulfates (SxS) and alkyl maltopyranosides (xM) reduce aggregation. Sodium dodecyl sulfate (SDS) binds to non-aggregated βLG in several steps, but reduction of aggregation was associated with the first binding step, which occurs far below the critical micelle concentration. In contrast, micellar concentrations of xMs are required to reduce aggregation. The ranking order for reduction of aggregation (normalized to their tendency to self-associate) was C10-C12>C8>C14 for SxS and C8>C10>C12>C14>C16 for xM. xTAC promote aggregation in the same ranking order as xM reduce it. We conclude that SxS reduce aggregation by stabilizing the protein's ligand-bound state (the melting temperature t(m) increases by up to 10°C) and altering its charge potential. xM monomers also stabilize the protein's ligand-bound state (increasing t(m) up to 6°C) but in the absence of charged head groups this is not sufficient by itself to prevent aggregation. Although micelles of both anionic and non-ionic surfactants destabilize βLG, they also solubilize unfolded protein monomers, leaving them unavailable for protein-protein association and thus inhibiting aggregation. Cationic surfactants promote aggregation by a combination of destabilization and charge neutralization. The food compatible surfactant sodium dodecanoate also inhibited aggregation well below the cmc, suggesting that surfactants may be a practical way to modulate whey protein properties.
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Affiliation(s)
- Jon G Hansted
- Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
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29
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Roman EA, Rosi P, González Lebrero MC, Wuilloud R, González Flecha FL, Delfino JM, Santos J. Gain of local structure in an amphipathic peptide does not require a specific tertiary framework. Proteins 2011; 78:2757-68. [PMID: 20607854 DOI: 10.1002/prot.22789] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this work, we studied how an amphipathic peptide of the surface of the globular protein thioredoxin, TRX94-108, acquires a native-like structure when it becomes involved in an apolar interaction network. We designed peptide variants where the tendency to form alpha-helical conformation is modulated by replacing each of the leucine amino acid residues by an alanine. The induction of structure caused by sodium dodecyl sulfate (SDS) binding was studied by capillary zone electrophoresis, circular dichroism, DOSY-NMR, and molecular dynamics simulations (MDS). In addition, we analyzed the strength of the interaction between a C18 RP-HPLC matrix and the peptides. The results presented here reveal that (a) critical elements in the sequence of the wild-type peptide stabilize a SDS/peptide supramolecular cluster; (b) the hydrophobic nature of the interaction between SDS molecules and the peptide constrains the ensemble of conformations; (c) nonspecific apolar surfaces are sufficient to stabilize peptide secondary structure. Remarkably, MDS shed light on a contact network formed by a limited number of SDS molecules that serves as a structural scaffold preserving the helical conformation of this module. This mechanism might prevail when a peptide with low helical propensity is involved in structure consolidation. We suggest that folding of peptides sharing this feature does not require a preformed tightly-packed protein core. Thus, the formation of specific tertiary interactions would be the consequence of peptide folding and not its cause. In this scenario, folding might be thought of as a process that includes unspecific rounds of structure stabilization guiding the protein to the native state.
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Affiliation(s)
- Ernesto A Roman
- Department of Biological Chemistry and Institute of Biochemistry and Biophysics (IQUIFIB), School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD, Buenos Aires, Argentina
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Liu W, Guo R. The Photostabilization of Hemoglobin in Triton X-100 Aqueous Solution and Triton X-100/n-C5H11OH/H2O Microemulsion. Photochem Photobiol 2010; 86:835-43. [DOI: 10.1111/j.1751-1097.2010.00752.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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