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Balafouti A, Forys A, Trzebicka B, Gerardos AM, Pispas S. Anionic Hyperbranched Amphiphilic Polyelectrolytes as Nanocarriers for Antimicrobial Proteins and Peptides. MATERIALS (BASEL, SWITZERLAND) 2023; 16:7702. [PMID: 38138846 PMCID: PMC10745097 DOI: 10.3390/ma16247702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023]
Abstract
This manuscript presents the synthesis of hyperbranched amphiphilic poly (lauryl methacrylate-co-tert-butyl methacrylate-co-methacrylic acid), H-P(LMA-co-tBMA-co-MAA) copolymers via reversible addition fragmentation chain transfer (RAFT) copolymerization of tBMA and LMA, and their post-polymerization modification to anionic amphiphilic polyelectrolytes. The focus is on investigating whether the combination of the hydrophobic characters of LMA and tBMA segments, as well as the polyelectrolyte and hydrophilic properties of MAA segments, both distributed within a unique hyperbranched polymer chain topology, would result in intriguing, branched copolymers with the potential to be applied in nanomedicine. Therefore, we studied the self-assembly behavior of these copolymers in aqueous media, as well as their ability to form complexes with cationic proteins, namely lysozyme (LYZ) and polymyxin (PMX). Various physicochemical characterization techniques, including size exclusion chromatography (SEC) and proton nuclear magnetic resonance (1H-NMR), verified the molecular characteristics of these well-defined copolymers, whereas light scattering and fluorescence spectroscopy techniques revealed promising nanoparticle (NP) self- and co-assembly properties of the copolymers in aqueous media.
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Affiliation(s)
- Anastasia Balafouti
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., 11635 Athens, Greece; (A.B.); (A.M.G.)
- Department of Chemistry, National and Kapodistrian University of Athens (NKUA), 15784 Athens, Greece
| | - Aleksander Forys
- Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 ul. M. Curie-Skłodowskiej, 41-819 Zabrze, Poland; (A.F.); (B.T.)
| | - Barbara Trzebicka
- Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 ul. M. Curie-Skłodowskiej, 41-819 Zabrze, Poland; (A.F.); (B.T.)
| | - Angelica Maria Gerardos
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., 11635 Athens, Greece; (A.B.); (A.M.G.)
- Department of Chemistry, National and Kapodistrian University of Athens (NKUA), 15784 Athens, Greece
| | - Stergios Pispas
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., 11635 Athens, Greece; (A.B.); (A.M.G.)
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Balafouti A, Pispas S. Hyperbranched Copolymers of Methacrylic Acid and Lauryl Methacrylate H-P(MAA-co-LMA): Synthetic Aspects and Interactions with Biorelevant Compounds. Pharmaceutics 2023; 15:pharmaceutics15041198. [PMID: 37111683 PMCID: PMC10140914 DOI: 10.3390/pharmaceutics15041198] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/05/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
The synthesis of novel copolymers using one-step reversible addition-fragmentation chain transfer (RAFT) copolymerization of biocompatible methacrylic acid (MAA), lauryl methacrylate (LMA), and difunctional ethylene glycol dimethacrylate (EGDMA) as a branching agent is reported. The obtained amphiphilic hyperbranched H-P(MAA-co-LMA) copolymers are molecularly characterized by size exclusion chromatography (SEC), FTIR, and 1H-NMR spectroscopy, and subsequently investigated in terms of their self-assembly behavior in aqueous media. The formation of nanoaggregates of varying size, mass, and homogeneity, depending on the copolymer composition and solution conditions such as concentration or pH variation, is demonstrated by light scattering and spectroscopic techniques. Furthermore, drug encapsulation properties are studied by incorporating the low bioavailability drug, curcumin, in the nano-aggregate hydrophobic domains, which can also act as a bioimaging agent. The interaction of polyelectrolyte MAA units with model proteins is described to examine protein complexation capacity relevant to enzyme immobilization strategies, as well as explore copolymer self-assembly in simulated physiological media. The results confirm that these copolymer nanosystems could provide competent biocarriers for imaging and drug or protein delivery/enzyme immobilization applications.
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Affiliation(s)
- Anastasia Balafouti
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., 11635 Athens, Greece
| | - Stergios Pispas
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., 11635 Athens, Greece
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3
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Atakay M. Monitoring Conformational Changes of Lysozyme–Polyelectrolyte Complexes Using Trapped Ion Mobility-Mass Spectrometry (IM-MS). ANAL LETT 2023. [DOI: 10.1080/00032719.2023.2173768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- Mehmet Atakay
- Department of Chemistry, Hacettepe University, Ankara, Turkey
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4
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Moses K, Van Tassel PR. Polyelectrolyte Influence on Beta-Hairpin Peptide Stability: A Simulation Study. J Phys Chem B 2023; 127:359-370. [PMID: 36574611 DOI: 10.1021/acs.jpcb.2c06641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Assemblies of proteins and charged macromolecules (polyelectrolytes) find important applications as pharmaceutical formulations, biocatalysts, and cell-contacting substrates. A key question is how the polymer component influences the structure and function of the protein. The present paper addresses the influence of charged polymers on the thermal stability of two model beta-hairpin-forming peptides through an all-atom, replica exchange molecular dynamics simulation. The (negatively charged) peptides consist of the terminal 16 amino acids of the B1 domain of Protein G (GB1) and a variant with three of the GB1 residues substituted with tryptophan (Tryptophan Zipper 4, or TZ4). A (cationic) lysine polymer is seen to thermally stabilize TZ4 and destabilize GB1, while a (also cationic) chitosan polymer slightly stabilizes GB1 but has essentially no effect on TZ4. Free energy profiles reveal folded and unfolded conformations to be separated by kinetic barriers generally acting in the direction of the thermodynamically favored state. Through application of an Ising-like statistical mechanical model, a mechanism is proposed based on competition between (indirect) entropic stabilization of folded versus unfolded states and (direct) competition for hydrogen-bonding and hydrophobic interactions. These findings have important implications to the design of polyelectrolyte-based materials for biomedical and biotechnological applications.
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Affiliation(s)
- Kevin Moses
- Dept. of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
| | - Paul R Van Tassel
- Dept. of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
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5
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Brunaugh AD, Seo H, Warnken Z, Ding L, Seo SH, Smyth HDC. Development and evaluation of inhalable composite niclosamide-lysozyme particles: A broad-spectrum, patient-adaptable treatment for coronavirus infections and sequalae. PLoS One 2021; 16:e0246803. [PMID: 33571320 PMCID: PMC7877651 DOI: 10.1371/journal.pone.0246803] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/26/2021] [Indexed: 12/24/2022] Open
Abstract
Niclosamide (NIC) has demonstrated promising in vitro antiviral efficacy against SARS-CoV-2, the causative agent of the COVID-19 pandemic. Though NIC is already FDA-approved, administration of the currently available oral formulation results in systemic drug levels that are too low for the inhibition of SARS-CoV-2. We hypothesized that the co-formulation of NIC with an endogenous protein, human lysozyme (hLYS), could enable the direct aerosol delivery of the drug to the respiratory tract as an alternative to oral delivery, thereby effectively treating COVID-19 by targeting the primary site of SARS-CoV-2 acquisition and spread. To test this hypothesis, we engineered and optimized composite particles containing NIC and hLYS suitable for delivery to the upper and lower airways via dry powder inhaler, nebulizer, and nasal spray. The novel formulation demonstrates potent in vitro and in vivo activity against two coronavirus strains, MERS-CoV and SARS-CoV-2, and may offer protection against methicillin-resistance staphylococcus aureus pneumonia and inflammatory lung damage occurring secondary to SARS-CoV-2 infections. The suitability of the formulation for all stages of the disease and low-cost development approach will ensure rapid clinical development and wide-spread utilization.
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Affiliation(s)
- Ashlee D. Brunaugh
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Hyojong Seo
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Zachary Warnken
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Li Ding
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Sang Heui Seo
- Laboratory of Influenza Research, College of Veterinary Medicine, Chungnam National University, Yoseong Gu, Dajeon, Korea
| | - Hugh D. C. Smyth
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
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6
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Mohammadi S, Khajeh K, Taghdir M, Ranjbar B. An experimental investigation on the influence of various buffer concentrations, osmolytes and gold nanoparticles on lysozyme: Spectroscopic and calorimetric study. Int J Biol Macromol 2021; 172:162-169. [PMID: 33412205 DOI: 10.1016/j.ijbiomac.2020.12.208] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 11/27/2022]
Abstract
Considering importance and several industrial applications of lysozyme, including natural antibiotic and preservative, identifier for the diagnosis of diseases, and extraction purposes, its reversibility and stability studies can be very important. In this paper, the role that buffer and osmolytes concentrations play on the thermodynamic stability of lysozyme denaturation process, that is a new simple and inexpensive method, was evaluated by Nano-DSC III, far- and near-UV CD and fluorescence techniques. In thermal denaturation study, RI and ΔG of protein increased from 25.62% to 58.82% and 48.87 to 63.63 kJ mol-1 with the increment of buffer and osmolytes concentrations, respectively. These changes showed a significant increase of 129.59% in RI and 28.16% in ΔG. The effect of buffer and osmolytes concentrations on the secondary and tertiary structures of protein was also investigated. The results indicated that increment of buffer and osmolytes concentrations increase rigidity and thermodynamic stability of protein. Also, structure of protein may be changed by its interaction with GNPs. Hence, interaction of lysozyme with GNPs was studied at the buffer and osmolytes concentrations that gives the maximum RI and ΔG, respectively. The results showed that molten globule-like state was formed by lysozyme in the presence of GNPs.
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Affiliation(s)
- Soraya Mohammadi
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | - Khosro Khajeh
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | - Majid Taghdir
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | - Bijan Ranjbar
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
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Malburet C, Leclercq L, Cotte JF, Thiebaud J, Cottet H. Study of Interactions between Antigens and Polymeric Adjuvants in Vaccines by Frontal Analysis Continuous Capillary Electrophoresis. Biomacromolecules 2020; 21:3364-3373. [PMID: 32609507 DOI: 10.1021/acs.biomac.0c00782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Vaccine adjuvants are used to enhance the immune response induced by antigens that have insufficient immunostimulatory capabilities. The present work aims at developing a frontal analysis continuous capillary electrophoresis (FACCE) methodology for the study of antigen-adjuvant interactions in vaccine products. After method optimization using three cationic model proteins, namely lysozyme, cytochrome c, and ribonuclease A, FACCE was successfully implemented to quantify the free antigen and thus to determine the interaction parameters (stoichiometry and binding constant) between an anionic polymeric adjuvant (polyacrylic acid, SPA09) and a cationic vaccine antigen in development for the treatment for Staphylococcus aureus. The influence of the ionic strength of the medium on the interactions was investigated. A strong dependence of the binding parameters with the ionic strength was observed. The concentration of the polymeric adjuvant was also found to significantly modify the ionic strength of the formulation, the extent of which could be estimated and corrected.
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Affiliation(s)
- Camille Malburet
- IBMM, University of Montpellier, CNRS, ENSCM, Montpellier, France.,Analytical Sciences, Sanofi Pasteur, 1541 Avenue Marcel Mérieux, Marcy-l'Étoile 69280, France
| | - Laurent Leclercq
- IBMM, University of Montpellier, CNRS, ENSCM, Montpellier, France
| | - Jean-François Cotte
- Analytical Sciences, Sanofi Pasteur, 1541 Avenue Marcel Mérieux, Marcy-l'Étoile 69280, France
| | - Jérôme Thiebaud
- Analytical Sciences, Sanofi Pasteur, 1541 Avenue Marcel Mérieux, Marcy-l'Étoile 69280, France
| | - Hervé Cottet
- IBMM, University of Montpellier, CNRS, ENSCM, Montpellier, France
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The evolutionarily conserved HtrA is associated with stress tolerance and protein homeostasis in the halotolerant cyanobacterium Halothece sp. PCC7418. Extremophiles 2020; 24:377-389. [PMID: 32146515 DOI: 10.1007/s00792-020-01162-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 02/21/2020] [Indexed: 12/22/2022]
Abstract
The HtrA protein family represents an important class of serine proteases that are widely distributed across taxa. These evolutionarily conserved proteins are crucial for survival and function as monitors of protein synthesis during various stresses. Here, we performed gene expression analysis of the entire set of putative serine protease genes in Halothece sp. PCC7418 under salt stress conditions. The gene-encoding HtrA2 (H3553) was highly upregulated. This gene was cloned and functionally characterized, and its sub-cellular localization was determined. The recombinant H3553 protein (rH3553) displayed a pH optimum of 8.0, remained stable at 45 °C, and its proteolytic activity was not affected by salts. H3553 completely degraded the unfolded model protein, β-casein. In contrast, the folded model substrates (lysozyme or BSA) were not degraded by rH3553. Denaturation of BSA at a high temperature significantly increased its degradation by rH3553. H3553 was detected in the soluble protein fraction as well as the plasma membrane and thylakoid membrane fractions. Interestingly, the majority of H3553 was present in the plasma membrane under salt and heat stress conditions. Thus, H3553 resides in multiple sub-cellular locations and its localization drastically changes after exposure to stresses. Taken together, H3553 underpins protein quality-control process and is involved in the response and adaptation to salinity and heat stresses.
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Doekhie A, Slade MN, Cliff L, Weaver L, Castaing R, Paulin J, Chen YC, Edler KJ, Koumanov F, Marchbank KJ, van den Elsen JMH, Sartbaeva A. Thermal resilience of ensilicated lysozyme via calorimetric and in vivo analysis. RSC Adv 2020; 10:29789-29796. [PMID: 35518265 PMCID: PMC9056174 DOI: 10.1039/d0ra06412b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/04/2020] [Indexed: 12/02/2022] Open
Abstract
Ensilication is a novel method of protein thermal stabilisation using silica. It uses a modified sol–gel process which tailor fits a protective silica shell around the solvent accessible protein surface. This, electrostatically attached, shell has been found to protect the protein against thermal influences and retains its native structure and function after release. Here, we report the calorimetric analysis of an ensilicated model protein, hen egg-white lysozyme (HEWL) under several ensilication conditions. DSC, TGA-DTA-MS, CD, were used to determine unfolding temperatures of native, released and ensilicated lysozyme to verify the thermal resilience of the ensilicated material. Our findings indicate that ensilication protects against thermal fluctuations even at low concentrations of silica used for ensilication. Secondly, the thermal stabilisation is comparable to lyophilisation, and in some cases is even greater than lyophilisation. Additionally, we performed a mouse in vivo study using lysozyme to demonstrate the antigenic retention over long-term storage. The results suggest that protein is confined within the ensilicated material, and thus is unable to unfold and denature but is still functional after long-term storage. Ensilication is a novel method of protein thermal stabilisation using silica. It uses a modified sol–gel process which tailor fits a protective silica shell around the protein to enable room temperature storage of biopharmaceuticals.![]()
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Affiliation(s)
- A. Doekhie
- Department of Chemistry
- University of Bath
- Bath
- UK
| | - M. N. Slade
- Department of Chemistry
- University of Bath
- Bath
- UK
| | - L. Cliff
- Department of Chemistry
- University of Bath
- Bath
- UK
| | - L. Weaver
- Department of Chemistry
- University of Bath
- Bath
- UK
| | - R. Castaing
- Material and Chemical Characterisation Facility
- University of Bath
- Bath
- UK
| | - J. Paulin
- The Medical School
- Framlington Place
- Newcastle University
- Newcastle upon Tyne
- UK
| | - Y.-C. Chen
- Department of Chemistry
- University of Bath
- Bath
- UK
| | - K. J. Edler
- Department of Chemistry
- University of Bath
- Bath
- UK
| | - F. Koumanov
- Department for Health
- University of Bath
- Bath
- UK
| | - K. J. Marchbank
- The Medical School
- Framlington Place
- Newcastle University
- Newcastle upon Tyne
- UK
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Andersson M, Hansson P. Binding of Lysozyme to Spherical Poly(styrenesulfonate) Gels. Gels 2018; 4:E9. [PMID: 30674786 PMCID: PMC6318605 DOI: 10.3390/gels4010009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/30/2017] [Accepted: 01/10/2018] [Indexed: 11/16/2022] Open
Abstract
Polyelectrolyte gels are useful as carriers of proteins and other biomacromolecules in, e.g., drug delivery. The rational design of such systems requires knowledge about how the binding and release are affected by electrostatic and hydrophobic interactions between the components. To this end we have investigated the uptake of lysozyme by weakly crosslinked spherical poly(styrenesulfonate) (PSS) microgels and macrogels by means of micromanipulator assisted light microscopy and small angle X-ray scattering (SAXS) in an aqueous environment. The results show that the binding process is an order of magnitude slower than for cytochrome c and for lysozyme binding to sodium polyacrylate gels under the same conditions. This is attributed to the formation of very dense protein-rich shells in the outer layers of the microgels with low permeability to the protein. The shells in macrogels contain 60 wt % water and nearly charge stoichiometric amounts of lysozyme and PSS in the form of dense complexes of radius 8 nm comprising 30⁻60 lysozyme molecules. With support from kinetic modelling results we propose that the rate of protein binding and the relaxation rate of the microgel are controlled by the protein mass transport through the shell, which is strongly affected by hydrophobic and electrostatic interactions. The mechanism explains, in turn, an observed dependence of the diffusion rate on the apparent degree of crosslinking of the networks.
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Affiliation(s)
- Martin Andersson
- Department of Pharmacy, Uppsala University, Box 580, SE-75123 Uppsala, Sweden.
| | - Per Hansson
- Department of Pharmacy, Uppsala University, Box 580, SE-75123 Uppsala, Sweden.
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Vander Straeten A, Bratek-Skicki A, Germain L, D'Haese C, Eloy P, Fustin CA, Dupont-Gillain C. Protein-polyelectrolyte complexes to improve the biological activity of proteins in layer-by-layer assemblies. NANOSCALE 2017; 9:17186-17192. [PMID: 29095455 DOI: 10.1039/c7nr04345g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A standard method of protein immobilization is proposed, based on the use of protein-polyelectrolyte complexes (PPCs) as building blocks for layer-by-layer assembly. Thicker multilayers, with a higher polyelectrolyte fraction, are obtained with PPCs compared to single protein molecules. Biological activity is not only maintained, but specific activity is also higher, as demonstrated for lysozyme-poly(styrene sulfonate) complexes. This is attributed to the more hydrated state of the assemblies. This new method of protein immobilization opens up perspectives for biotechnology and biomedical applications.
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Affiliation(s)
- A Vander Straeten
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Place Louis Pasteur, 1 bte L4.01.10, B-1348 Louvain-la-Neuve, Belgium.
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12
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A comparative study of fibrillation kinetics of two homologous proteins under identical solution condition. Biochimie 2017; 132:75-84. [DOI: 10.1016/j.biochi.2016.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/03/2016] [Indexed: 02/08/2023]
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13
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Wu FG, Jiang YW, Chen Z, Yu ZW. Folding Behaviors of Protein (Lysozyme) Confined in Polyelectrolyte Complex Micelle. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:3655-3664. [PMID: 27022665 DOI: 10.1021/acs.langmuir.6b00235] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The folding/unfolding behavior of proteins (enzymes) in confined space is important for their properties and functions, but such a behavior remains largely unexplored. In this article, we reported our finding that lysozyme and a double hydrophilic block copolymer, methoxypoly(ethylene glycol)5K-block-poly(l-aspartic acid sodium salt)10 (mPEG(5K)-b-PLD10), can form a polyelectrolyte complex micelle with a particle size of ∼30 nm, as verified by dynamic light scattering and transmission electron microscopy. The unfolding and refolding behaviors of lysozyme molecules in the presence of the copolymer were studied by microcalorimetry and circular dichroism spectroscopy. Upon complex formation with mPEG(5K)-b-PLD10, lysozyme changed from its initial native state to a new partially unfolded state. Compared with its native state, this copolymer-complexed new folding state of lysozyme has different secondary and tertiary structures, a decreased thermostability, and significantly altered unfolding/refolding behaviors. It was found that the native lysozyme exhibited reversible unfolding and refolding upon heating and subsequent cooling, while lysozyme in the new folding state (complexed with the oppositely charged PLD segments of the polymer) could unfold upon heating but could not refold upon subsequent cooling. By employing the heating-cooling-reheating procedure, the prevention of complex formation between lysozyme and polymer due to the salt screening effect was observed, and the resulting uncomplexed lysozyme regained its proper unfolding and refolding abilities upon heating and subsequent cooling. Besides, we also pointed out the important role the length of the PLD segment played during the formation of micelles and the monodispersity of the formed micelles. Furthermore, the lysozyme-mPEG(5K)-b-PLD10 mixtures prepared in this work were all transparent, without the formation of large aggregates or precipitates in solution as frequently observed in other protein-polyelectrolyte systems. Hence, the present protein-PEGylated poly(amino acid) mixture provides an ideal water-soluble model system to study the important role of electrostatic interaction in the complexation between proteins and polymers, leading to important new knowledge on the protein-polymer interactions. Moreover, the polyelectrolyte complex micelle formed between protein and PEGylated polymer may provide a good drug delivery vehicle for therapeutic proteins.
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Affiliation(s)
- Fu-Gen Wu
- Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University , Beijing 100084, P. R. China
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, China
| | - Yao-Wen Jiang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, China
| | - Zhan Chen
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Zhi-Wu Yu
- Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University , Beijing 100084, P. R. China
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