1
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Hamley IW, Castelletto V, Hermida-Merino D, Rosenthal M. Cyclodextrin-Induced Suppression of PEG Crystallization from the Melt in a PEG-Peptide Conjugate. Chembiochem 2024; 25:e202400396. [PMID: 38775269 DOI: 10.1002/cbic.202400396] [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: 04/30/2024] [Revised: 05/17/2024] [Indexed: 06/29/2024]
Abstract
The influence of alpha-cyclodextrin (αCD) on PEG crystallization is examined for a peptide-PEG conjugate, YYKLVFF-PEG3k comprising an amyloid peptide YYKLVFF linked to PEG with molar mass 3 kg mol-1. Remarkably, differential scanning calorimetry (DSC) and simultaneous synchrotron small-angle/wide-angle X-ray scattering (SAXS/WAXS) show that crystallization of PEG is suppressed by αCD, provided that the cyclodextrin content is sufficient. A hexagonal mesophase is formed instead. The αCD threading reduces the conformational flexibility of PEG, and hence suppresses crystallization. These results show that addition of cyclodextrins can be used to tune the crystallization of peptide-polymer conjugates and potentially other polymer/biomolecular hybrids.
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Affiliation(s)
- Ian W Hamley
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - Valeria Castelletto
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - Daniel Hermida-Merino
- DUBBLE-CRG @ ESRF, CS40220, The European Synchrotron, 71, Avenue des Martyrs, 38043, Grenoble Cedex 9, France
| | - Martin Rosenthal
- DUBBLE-CRG @ ESRF, CS40220, The European Synchrotron, 71, Avenue des Martyrs, 38043, Grenoble Cedex 9, France
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2
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Ricardo MG, Seeberger PH. Merging Solid-Phase Peptide Synthesis and Automated Glycan Assembly to Prepare Lipid-Peptide-Glycan Chimeras. Chemistry 2023; 29:e202301678. [PMID: 37358020 DOI: 10.1002/chem.202301678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 06/24/2023] [Accepted: 06/26/2023] [Indexed: 06/27/2023]
Abstract
Biomaterials with improved biological features can be obtained by conjugating glycans to nanostructured peptides. Creating peptide-glycan chimeras requires superb chemoselectivity. We expedite access to such chimeras by merging peptide and glycan solid-phase syntheses employing a bifunctional monosaccharide. The concept was explored in the context of the on-resin generation of a model α(1→6)tetramannoside linked to peptides, lipids, steroids, and adamantane. Chimeras containing a β(1→6)tetraglucoside and self-assembling peptides such as FF, FFKLVFF, and the amphiphile palmitoyl-VVVAAAKKK were prepared in a fully automated manner. The robust synthetic protocol requires a single purification step to obtain overall yields of about 20 %. The β(1→6)tetraglucoside FFKLVFF chimera produces micelles rather than nanofibers formed by the peptide alone as judged by microscopy and circular dichroism. The peptide amphiphile-glycan chimera forms a disperse fiber network, creating opportunities for new glycan-based nanomaterials.
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Affiliation(s)
- Manuel G Ricardo
- Department of Biomolecular Systems, Max-Planck-Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Peter H Seeberger
- Department of Biomolecular Systems, Max-Planck-Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476, Potsdam, Germany
- Institute of Chemistry and Biochemistry, Freie Universitaet Berlin, Arnimallee 22, 14195, Berlin, Germany
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3
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Hamley IW, Castelletto V. Small-angle scattering techniques for peptide and peptide hybrid nanostructures and peptide-based biomaterials. Adv Colloid Interface Sci 2023; 318:102959. [PMID: 37473606 DOI: 10.1016/j.cis.2023.102959] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/22/2023]
Abstract
The use of small-angle scattering (SAS) in the study of the self-assembly of peptides and peptide conjugates (lipopeptides, polymer-peptide conjugates and others) is reviewed, highlighting selected research that illustrates different methods and analysis techniques. Both small-angle x-ray scattering (SAXS) and small-angle neutron scattering (SANS) are considered along with examples that exploit their unique capabilities. For SAXS, this includes the ability to perform rapid measurements enabling high throughput or fast kinetic studies and measurements under dilute conditions. For SANS, contrast variation using H2O/D2O mixtures enables the study of peptides interacting with lipids and TR-SANS (time-resolved SANS) studies of exchange kinetics and/or peptide-induced structural changes. Examples are provided of studies measuring form factors of different self-assembled structures (micelles, fibrils, nanotapes, nanotubes etc) as well as structure factors from ordered phases (lyotropic mesophases), peptide gels and hybrid materials such as membranes formed by mixing peptides with polysaccharides or peptide/liposome mixtures. SAXS/WAXS (WAXS: wide-angle x-ray scattering) on peptides and peptide hybrids is also discussed, and the review concludes with a perspective on potential future directions for research in the field.
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Affiliation(s)
- Ian W Hamley
- Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK.
| | - Valeria Castelletto
- Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK
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4
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Diaferia C, Balasco N, Sibillano T, Ghosh M, Adler-Abramovich L, Giannini C, Vitagliano L, Morelli G, Accardo A. Amyloid-Like Fibrillary Morphology Originated by Tyrosine-Containing Aromatic Hexapeptides. Chemistry 2018; 24:6804-6817. [PMID: 29504716 DOI: 10.1002/chem.201800351] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Indexed: 01/04/2023]
Abstract
Phenylalanine-based nanostructures have attracted the attention of the material science community for their functional properties. These properties strongly depend on the hierarchic organization of the nanostructure that in turn can be finely tuned by punctual chemical modifications of the building blocks. Herein, we investigate how the partial or the complete replacement of the Phe residues in PEG8 -(Phe)6 (PEG8 -F6) with tyrosines to generate PEG8 -(Phe-Tyr)3 (PEG8 -(FY)3) or PEG8 -(Tyr)6 (PEG8 -Y6) affects the structural/functional properties of the nanomaterial formed by the parental compound. Moreover, the effect of the PEG derivatization was evaluated through the characterization of the peptides without the PEG moiety (Tyr)6 (Y6) and (Phe-Tyr)3 ((FY)3). Both PEG8 -Y6 and PEG8 -(FY)3 can self-assemble in water at micromolar concentrations in β-sheet-rich nanostructures. However, WAXS diffraction patterns of these compounds present significant differences. PEG8 -(FY)3 shows a 2D WAXS oriented fiber diffraction profile characterized by the concomitant presence of a 4.7 Å meridional and a 12.5 Å equatorial reflection that are generally associated with cross-β structure. On the other hand, the pattern of PEG8 -Y6 is characterized by the presence of circles typically observed in the presence of PEG crystallization. Molecular modeling and dynamics provide an atomic structural model of the peptide spine of these compounds that is in good agreement with WAXS experimental data. Gelation phenomenon was only detected for PEG8 -(FY)3 above a concentration of 1.0 wt % as confirmed by storage (G'≈100 Pa) and loss (G''≈28 Pa) moduli in rheological studies. The cell viability on CHO cells of this soft hydrogel was certified to be 90 % after 24 hours of incubation.
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Affiliation(s)
- Carlo Diaferia
- Department of Pharmacy, Research Centre on Bioactive Peptides (CIRPeB), University of Naples "Federico II" and DFM Scarl, Via Mezzocannone 16, 80134, Naples, Italy
| | - Nicole Balasco
- Institute of Biostructures and Bioimaging (IBB), CNR, Via Mezzocannone 16, 80134, Naples, Italy
| | - Teresa Sibillano
- Institute of Crystallography (IC), CNR, Via Amendola 122, 70126, Bari, Italy
| | - Moumita Ghosh
- Department of Oral Biology, The Goldschleger School of Dental Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Lihi Adler-Abramovich
- Department of Oral Biology, The Goldschleger School of Dental Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Cinzia Giannini
- Institute of Crystallography (IC), CNR, Via Amendola 122, 70126, Bari, Italy
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging (IBB), CNR, Via Mezzocannone 16, 80134, Naples, Italy
| | - Giancarlo Morelli
- Department of Pharmacy, Research Centre on Bioactive Peptides (CIRPeB), University of Naples "Federico II" and DFM Scarl, Via Mezzocannone 16, 80134, Naples, Italy
| | - Antonella Accardo
- Department of Pharmacy, Research Centre on Bioactive Peptides (CIRPeB), University of Naples "Federico II" and DFM Scarl, Via Mezzocannone 16, 80134, Naples, Italy
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5
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Kirkham S, Castelletto V, Hamley IW, Reza M, Ruokolainen J, Hermida-Merino D, Bilalis P, Iatrou H. Self-Assembly of Telechelic Tyrosine End-Capped PEO and Poly(alanine) Polymers in Aqueous Solution. Biomacromolecules 2016; 17:1186-97. [DOI: 10.1021/acs.biomac.6b00023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Steven Kirkham
- School
of Chemistry, Pharmacy and Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
| | - Valeria Castelletto
- School
of Chemistry, Pharmacy and Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
| | - Ian William Hamley
- School
of Chemistry, Pharmacy and Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
| | - Mehedi Reza
- Department
of Applied Physics, Aalto University School of Science, P.O. Box 15100 FI-00076 Aalto, Finland
| | - Janne Ruokolainen
- Department
of Applied Physics, Aalto University School of Science, P.O. Box 15100 FI-00076 Aalto, Finland
| | | | - Panayiotis Bilalis
- University of Athens, Department of Chemistry, Panepistimiopolis Zografou, 157 71 Athens, Greece
| | - Hermis Iatrou
- University of Athens, Department of Chemistry, Panepistimiopolis Zografou, 157 71 Athens, Greece
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6
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Li X, Lam CN, Sánchez-Diáz LE, Smith GS, Olsen BD, Chen WR. Scattering from Colloid-Polymer Conjugates with Excluded Volume Effect. ACS Macro Lett 2015; 4:165-170. [PMID: 35596423 DOI: 10.1021/mz5006958] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This work presents scattering functions of conjugates consisting of a colloid particle and a self-avoiding polymer chain as a model for protein-polymer conjugates and nanoparticle-polymer conjugates in solution. The model is directly derived from the two-point correlation function with the inclusion of excluded volume effects. The dependence of the calculated scattering function on the geometric shape of the colloid and polymer stiffness is investigated. The model is able to describe the experimental scattering signature of the solutions of suspending hard particle-polymer conjugates and provide additional conformational information. This model explicitly elucidates the link between the global conformation of a conjugate and the microstructure of its constituent components.
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Affiliation(s)
- Xin Li
- Biology
and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Christopher N. Lam
- Department
of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Luis E. Sánchez-Diáz
- Biology
and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Gregory S. Smith
- Biology
and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Bradley D. Olsen
- Department
of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wei-Ren Chen
- Biology
and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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7
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Krishnaji ST, Huang W, Cebe P, Kaplan DL. Influence of Solution Parameters on Phase Diagram of Recombinant Spider Silk-Like Block Copolymers. MACROMOL CHEM PHYS 2014. [DOI: 10.1002/macp.201400135] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sreevidhya Tarakkad Krishnaji
- Department of Chemistry; Tufts University; Medford MA 02155 USA
- Department of Biomedical Engineering; Tufts University; Medford MA 02155 USA
| | - Wenwen Huang
- Department of Physics & Astronomy; Center for Nanoscopic Physics, Tufts University; Medford MA 02155 USA
| | - Peggy Cebe
- Department of Physics & Astronomy; Center for Nanoscopic Physics, Tufts University; Medford MA 02155 USA
| | - David L. Kaplan
- Department of Chemistry; Tufts University; Medford MA 02155 USA
- Department of Biomedical Engineering; Tufts University; Medford MA 02155 USA
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8
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Abstract
The remarkable diversity of the self-assembly behavior of PEG-peptides is reviewed, including self-assemblies formed by PEG-peptides with β-sheet and α-helical (coiled-coil) peptide sequences. The modes of self-assembly in solution and in the solid state are discussed. Additionally, applications in bionanotechnology and synthetic materials science are summarized.
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Affiliation(s)
- Ian W Hamley
- Department of Chemistry, University of Reading , Whiteknights, Reading RG6 6AD, United Kingdom
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9
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Paira TK, Saha A, Banerjee S, Das T, Das P, Jana NR, Mandal TK. Fluorescent amphiphilic PEG-peptide-PEG triblock conjugate micelles for cell imaging. Macromol Biosci 2014; 14:929-35. [PMID: 24687698 DOI: 10.1002/mabi.201400083] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Indexed: 12/18/2022]
Abstract
A fluorescent amphiphilic poly(ethylene glycol)-peptide-fluorophore-peptide-poly(ethylene glycol) (PEG-Pep-F-Pep-PEG) triblock conjugate with a hydrophobic fluorophore moiety at the centre of the chain is synthesized by "grafting to" technique based on Schiff-base coupling chemistry. The conjugate is characterized by nuclear magnetic resonance (NMR), circular dichroism (CD), and fluorescence spectroscopy techniques. The aqueous solution of the triblock conjugate emits blue light and exhibits a fluorescence emission band at 430 nm. The amphiphilic conjugate molecules undergo self-assembly into micelles (D ≈ 15-20 nm) in aqueous solution as confirmed from transmission electron microscopy (TEM) and dynamic light scattering (DLS). The critical aggregation concentration is determined by pyrene fluorescence assay and is found to be 0.051 mg mL(-1) . The highly stable and low toxic fluorescent PEG-Pep-F-Pep-PEG conjugate micelles are used for imaging of HeLa cells.
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Affiliation(s)
- Tapas K Paira
- Polymer Science Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India
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10
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Affiliation(s)
- Jenny Malmström
- Polymer Electronics Research Centre; School of Chemical Sciences; University of Auckland; Auckland 1142 New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology; Victoria University of Wellington; P.O. Box 600 Wellington 6140 New Zealand
| | - Jadranka Travas-Sejdic
- Polymer Electronics Research Centre; School of Chemical Sciences; University of Auckland; Auckland 1142 New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology; Victoria University of Wellington; P.O. Box 600 Wellington 6140 New Zealand
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11
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Murase SK, Haspel N, del Valle LJ, Perpète EA, Michaux C, Nussinov R, Puiggalí J, Alemán C. Molecular characterization of l-phenylalanine terminated poly(l-lactide) conjugates. RSC Adv 2014. [DOI: 10.1039/c4ra01534g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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12
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Castelletto V, Gouveia RJ, Connon CJ, Hamley IW. Self-assembly and bioactivity of a polymer/peptide conjugate containing the RGD cell adhesion motif and PEG. Eur Polym J 2013. [DOI: 10.1016/j.eurpolymj.2013.02.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Ren K, Cheng Y, He C, Xiao C, Li G, Chen X. The effect of alkyl side groups on the secondary structure and crystallization of poly(ethylene glycol)-block-polypeptide copolymers. POLYMER 2013. [DOI: 10.1016/j.polymer.2013.02.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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14
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Abstract
Advances in genetic engineering have led to the synthesis of protein-based block copolymers with control of chemistry and molecular weight, resulting in unique physical and biological properties. The benefits from incorporating peptide blocks into copolymer designs arise from the fundamental properties of proteins to adopt ordered conformations and to undergo self-assembly, providing control over structure formation at various length scales when compared to conventional block copolymers. This review covers the synthesis, structure, assembly, properties, and applications of protein-based block copolymers.
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Affiliation(s)
- Olena S Rabotyagova
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
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15
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Castelletto V, Newby GE, Zhu Z, Hamley IW, Noirez L. Self-assembly of PEGylated peptide conjugates containing a modified amyloid beta-peptide fragment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9986-96. [PMID: 20450168 DOI: 10.1021/la100110f] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The self-assembly of PEGylated peptides containing a modified sequence from the amyloid beta peptide, FFKLVFF, has been studied in aqueous solution. PEG molar masses PEG1k, PEG2k, and PEG10k were used in the conjugates. It is shown that the three FFKLVFF-PEG hybrids form fibrils comprising a FFKLVFF core and a PEG corona. The beta-sheet secondary structure of the peptide is retained in the FFKLVFF fibril core. At sufficiently high concentrations, FFKLVFF-PEG1k and FFKLVFF-PEG2k form a nematic phase, while PEG10k-FFKLVFF exhibits a hexagonal columnar phase. Simultaneous small angle neutron scattering/shear flow experiments were performed to study the shear flow alignment of the nematic and hexagonal liquid crystal phases. On drying, PEG crystallization occurs without disruption of the FFKLVFF beta-sheet structure leading to characteristic peaks in the X-ray diffraction pattern and FTIR spectra. The stability of beta-sheet structures was also studied in blends of FFKLVFF-PEG conjugates with poly(acrylic acid) (PAA). While PEG crystallization is only observed up to 25% PAA content in the blends, the FFKLVFF beta-sheet structure is retained up to 75% PAA.
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Affiliation(s)
- V Castelletto
- Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
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16
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Rabotyagova OS, Cebe P, Kaplan DL. Role of polyalanine domains in beta-sheet formation in spider silk block copolymers. Macromol Biosci 2010; 10:49-59. [PMID: 19890885 DOI: 10.1002/mabi.200900203] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Genetically engineered spider silk-like block copolymers were studied to determine the influence of polyalanine domain size on secondary structure. The role of polyalanine block distribution on beta-sheet formation was explored using FT-IR and WAXS. The number of polyalanine blocks had a direct effect on the formation of crystalline beta-sheets, reflected in the change in crystallinity index as the blocks of polyalanines increased. WAXS analysis confirmed the crystalline nature of the sample with the largest number of polyalanine blocks. This approach provides a platform for further exploration of the role of specific amino acid chemistries in regulating the assembly of beta-sheet secondary structures, leading to options to regulate material properties through manipulation of this key component in spider silks.
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Affiliation(s)
- Olena S Rabotyagova
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
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17
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Castelletto V, Newby GE, Hermida Merino D, Hamley IW, Liu D, Noirez L. Self-assembly of an amyloid peptide fragment–PEG conjugate: lyotropic phase formation and influence of PEG crystallization. Polym Chem 2010. [DOI: 10.1039/b9py00349e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The self-assembly of polymer–peptide conjugates containing a modified amyloid peptide sequence is studied. Lyotropic liquid crystal phases are observed in water, and PEG crystallization is probed.
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Affiliation(s)
| | - G. E. Newby
- Dept. of Chemistry
- University of Reading
- Reading
- UK
| | | | - I. W. Hamley
- Dept. of Chemistry
- University of Reading
- Reading
- UK
- Diamond Light Source
| | - D. Liu
- Dept. of Physics
- University of Surrey
- Guildford
- UK
| | - L. Noirez
- CEA-CNRS Laboratoire Léon Brillouin
- Gif-sur-Yvette
- France
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18
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Castelletto V, Hamley IW. Self assembly of a model amphiphilic phenylalanine peptide/polyethylene glycol block copolymer in aqueous solution. Biophys Chem 2009; 141:169-74. [PMID: 19232813 DOI: 10.1016/j.bpc.2009.01.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2008] [Revised: 01/23/2009] [Accepted: 01/23/2009] [Indexed: 11/26/2022]
Abstract
There has been great interest recently in peptide amphiphiles and block copolymers containing biomimetic peptide sequences due to applications in bionanotechnology. We investigate the self-assembly of the peptide-PEG amphiphile FFFF-PEG5000 containing the hydrophobic sequence of four phenylalanine residues conjugated to PEG of molar mass 5000. This serves as a simple model peptide amphiphile. At very low concentration, association of hydrophobic aromatic phenylalanine residues occurs, as revealed by circular dichroism and UV/vis fluorescence experiments. A critical aggregation concentration associated with the formation of hydrophobic domains is determined through pyrene fluorescence assays. At higher concentration, defined beta-sheets develop as revealed by FTIR spectroscopy and X-ray diffraction. Transmission electron microscopy reveals self-assembled straight fibril structures. These are much shorter than those observed for amyloid peptides, the finite length may be set by the end cap energy due to the hydrophobicity of phenylalanine. The combination of these techniques points to different aggregation processes depending on concentration. Hydrophobic association into irregular aggregates occurs at low concentration, well-developed beta-sheets only developing at higher concentration. Drying of FFFF-PEG5000 solutions leads to crystallization of PEG, as confirmed by polarized optical microscopy (POM), FTIR and X-ray diffraction (XRD). PEG crystallization does not disrupt local beta-sheet structure (as indicated by FTIR and XRD). However on longer lengthscales the beta-sheet fibrillar structure is perturbed because spherulites from PEG crystallization are observed by POM.
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19
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Rabotyagova OS, Cebe P, Kaplan DL. Self-Assembly of Genetically Engineered Spider Silk Block Copolymers. Biomacromolecules 2009; 10:229-36. [DOI: 10.1021/bm800930x] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Olena S. Rabotyagova
- Departments of Biomedical Engineering, Chemistry and Physics, Tufts University, Medford, Massachusetts 02155
| | - Peggy Cebe
- Departments of Biomedical Engineering, Chemistry and Physics, Tufts University, Medford, Massachusetts 02155
| | - David L. Kaplan
- Departments of Biomedical Engineering, Chemistry and Physics, Tufts University, Medford, Massachusetts 02155
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20
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Hamley I, Krysmann M, Kelarakis A, Castelletto V, Noirez L, Hule R, Pochan D. Nematic and Columnar Ordering of a PEG-Peptide Conjugate in Aqueous Solution. Chemistry 2008; 14:11369-75. [DOI: 10.1002/chem.200800817] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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