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O'Neill N, Lima TA, Furlan Ferreira F, Alvarez NJ, Schweitzer-Stenner R. Determining the nanostructure and main axis of gly-his-gly fibrils using the amide I' bands in FTIR, VCD, and Raman spectra. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 306:123584. [PMID: 37956526 DOI: 10.1016/j.saa.2023.123584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/29/2023] [Accepted: 10/26/2023] [Indexed: 11/15/2023]
Abstract
The zwitterionic tripeptide glycyl-histidine-glycine (GHG) has been shown to self-assemble into visible crystalline fibrils that form a gel-supporting network with a very high storage modulus. Here we elaborate on the theory and experimental setup behind our novel approach employed to determining the main fibril axis for these gel-forming fibrils by simulating the amide I band profile for infrared absorption (IR), vibrational circular dichroism (VCD), and visible Raman scattering. We also highlight that combining these three vibrational spectroscopies can help in validating structures that are solved using powder x-ray diffraction analysis (PXRD). The PXRD analysis yielded a GHG fibril unit cell with P21 symmetry containing two peptide monomers and two water molecules. The monomers adopt a conformation reminiscent of the distorted polyproline II conformation obtained for tri-lysine in aqueous solution. Stabilization occurs primarily through peptide-peptide intermolecular hydrogen bond interactions, while the role of water in peptide hydration is minimal. The comparison of simulated and experimental amide I' band profiles suggests that the xz plane of the crystal unit cell is being predominantly probed in the experimental IR and VCD spectra, with the x axis of the unit cell pointing in the direction of the main fibril axis. The monomer peptide in the unit cell interacts with six adjacent peptides forming hydrophobic channels by edge-to-face and parallel-displaced ππstacking in the y direction. These cores are further stabilized by a plethora of intermolecular interactions in the x and z directions. Our result suggests that the hydrophobic xz-surfaces would be a good target for the adsorption of hydrophobic drugs.
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Affiliation(s)
- Nichole O'Neill
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA; Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA
| | - Thamires A Lima
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA
| | - Fabio Furlan Ferreira
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP 09210-580, Brazil
| | - Nicolas J Alvarez
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA.
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2
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Hofmaier M, Heger JE, Lentz S, Schwarz S, Müller-Buschbaum P, Scheibel T, Fery A, Müller M. Influence of the Sequence Motive Repeating Number on Protein Folding in Spider Silk Protein Films. Biomacromolecules 2023; 24:5707-5721. [PMID: 37934893 DOI: 10.1021/acs.biomac.3c00688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Like multiblock copolymers, spider silk proteins are built of repetitive sequence motives. One prominent repetitive motif is based on the consensus sequence of spidroin 4 of the spider Araneus diadematus ADF4. The number x of the repeating sequence motives (C) determines the molecular weight of the recombinant ADF4-based, engineered spider silk protein denoted as eADF4(Cx). eADF4(Cx) can be used as a model for intrinsically disordered proteins (IDP) and to elucidate their folding. Herein, the influence of the variation of the sequence motive repeating number x (x = 1, 2, 4, 8, 16) on the protein folding within eADF4(Cx) films was investigated. eADF4(Cx) films were cast from 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) solutions onto planar silicon model substrates, revealing mainly helical or random coil structure. Upon treatment with methanol vapor (ptm), the formation of crystalline β-sheets was triggered. Dichroic Fourier-transform infrared (FTIR) spectroscopy, circular dichroism, spectroscopic ellipsometry, atomic force microscopy, grazing-incidence small-angle X-ray scattering (GISAXS), grazing-incidence wide-angle X-ray scattering (GIWAXS), and electrokinetic and contact angle measurements were used to get information concerning the secondary structure and folding kinetics, orientation of β-sheets, the ratio of parallel/antiparallel β-sheets, domain sizes and distributions, surface topography, surface potential, hydrophobicity and the film integrity under water. Significant differences in the final β-sheet content, the share of antiparallel β-sheet structures, film integrity, surface potential, and isoelectric points between eADF4(Cx) with x = 1, 2 and eADF4(Cx) with x = 4, 8, 16 gave new insights in the molecular weight-dependent structure formation and film properties of IDP systems. GISAXS and kinetic measurements confirmed a relation between β-sheet crystal growth rate and final β-sheet crystal size. Further, competing effects of reduced diffusibility hindering accelerated crystal growth and enhanced backfolding promoting accelerated crystal growth with increasing molecular weight were discussed.
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Affiliation(s)
- Mirjam Hofmaier
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
- Chair of Physical Chemistry of Polymeric Materials, Technical University Dresden (TUD), Dresden 01069, Germany
| | - Julian E Heger
- TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, Technical University of Munich, Garching 85748, Germany
| | - Sarah Lentz
- Functional Polymer Interfaces Group, University of Bayreuth, Bayreuth 95447, Germany
| | - Simona Schwarz
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
| | - Peter Müller-Buschbaum
- TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, Technical University of Munich, Garching 85748, Germany
- Heinz Maier-Leibnitz Zentrum (MLZ), Technical University of Munich, Garching 85748, Germany
| | - Thomas Scheibel
- Chair of Biomaterials, University of Bayreuth, Bayreuth 95447, Germany
- Bayreuth Center of Colloids and Interfaces (BZKG), University of Bayreuth, Bayreuth 95440, Germany
- Bayreuth Center for Molecular Bioscience (BZMB), University of Bayreuth, Bayreuth 95440, Germany
- Bayreuth Center for Material Science and Engineering (BayMAT), Universität Bayreuth, Bayreuth 95440, Germany
- Bavarian Polymer Institute (BPI), University of Bayreuth, Bayreuth 95440, Germany
| | - Andreas Fery
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
- Chair of Physical Chemistry of Polymeric Materials, Technical University Dresden (TUD), Dresden 01069, Germany
| | - Martin Müller
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
- Chair of Macromolecular Chemistry, Technical University of Dresden (TUD), Dresden 01062, Germany
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3
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Schweitzer-Stenner R, Kurbaj R, O'Neill N, Andrews B, Shah R, Urbanc B. Conformational Manifold Sampled by Two Short Linear Motif Segments Probed by Circular Dichroism, Vibrational, and Nuclear Magnetic Resonance Spectroscopy. Biochemistry 2023; 62:2571-2586. [PMID: 37595285 DOI: 10.1021/acs.biochem.3c00212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
Disordered protein segments called short linear motifs (SLiM) serve as recognition sites for a variety of biological processes and act as targeting signals, modification, and ligand binding sites. While SLiMs do not adopt one of the known regular secondary structures, the conformational distribution might still reflect the structural propensities of their amino acid residues and possible interactions between them. In the past, conformational analyses of short peptides provided compelling evidence for the notion that individual residues are less conformationally flexible than locally expected for a random coil. Here, we combined various spectroscopies (NMR, IR, vibrational, and UV circular dichroism) to determine the Ramachandran plots of two SLiM motifs, i.e., GRRDSG and GRRTSG. They are two representatives of RxxS motifs that are capable of being phosphorylated by protein kinase A, an enzyme that plays a fundamental role in a variety of biological processes. Our results reveal that the nearest and non-nearest interactions between residues cause redistributions between polyproline II and β-strand basins while concomitantly stabilizing extended relative to turn-forming and helical structures. They also cause shifts in basin positions. With increasing temperature, β-strand populations become more populated at the expense of polyproline II. While molecular dynamics simulations with Amber ff14SB and CHARMM 36m force fields indicate residue-residue interactions, they do not account for the observed structural changes.
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Affiliation(s)
| | - Raghed Kurbaj
- Department of Chemistry, Drexel University, Philadelphia, PA19104Pennsylvania,United States
| | - Nichole O'Neill
- Department of Chemistry, Drexel University, Philadelphia, PA19104Pennsylvania,United States
| | - Brian Andrews
- Department of Physics, Drexel University, Philadelphia,PA19104Pennsylvania,United States
| | - Riya Shah
- Department of Physics, Drexel University, Philadelphia,PA19104Pennsylvania,United States
| | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia,PA19104Pennsylvania,United States
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4
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Thursch LJ, Lima TA, O'Neill N, Ferreira FF, Schweitzer-Stenner R, Alvarez NJ. Influence of central sidechain on self-assembly of glycine-x-glycine peptides. SOFT MATTER 2023; 19:394-409. [PMID: 36454226 DOI: 10.1039/d2sm01082h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Low molecular weight gelators (LMWGs) are the subject of intense research for a range of biomedical and engineering applications. Peptides are a special class of LMWG, which offer infinite sequence possibilities and, therefore, engineered properties. This work examines the propensity of the GxG peptide family, where x denotes a guest residue, to self-assemble into fibril networks via changes in pH and ethanol concentration. These triggers for gelation are motivated by recent work on GHG and GAG, which unexpectedly self-assemble into centimeter long fibril networks with unique rheological properties. The propensity of GxG peptides to self-assemble, and the physical and chemical properties of the self-assembled structures are characterized by microscopy, spectroscopy, rheology, and X-ray diffraction. Interestingly, we show that the number, length, size, and morphology of the crystalline self-assembled aggregates depend significantly on the x-residue chemistry and the solution conditions, i.e. pH, temperature, peptide concentration, etc. The different x-residues allow us to probe the importance of different peptide interactions, e.g. π-π stacking, hydrogen bonding, and hydrophobicity, on the formation of fibrils. We conclude that fibril formation requires π-π stacking interactions in pure water, while hydrogen bonding can form fibrils in the presence of ethanol-water solutions. These results validate and support theoretical arguments on the propensity for self-assembly and leads to a better understanding of the relationship between peptide chemistry and fibril self-assembly. Overall, GxG peptides constitute a unique family of peptides, whose characterization will aid in advancing our understanding of self-assembly driving forces for fibril formation in peptide systems.
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Affiliation(s)
- Lavenia J Thursch
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA.
| | - Thamires A Lima
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA.
| | - Nichole O'Neill
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA.
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA.
| | - Fabio F Ferreira
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo, Brazil
| | | | - Nicolas J Alvarez
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA.
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5
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O'Neill N, Lima TA, Ferreira FF, Thursch L, Alvarez N, Schweitzer-Stenner R. Forbidden Secondary Structures Found in Gel-Forming Fibrils of Glycylphenylalanylglycine. J Phys Chem B 2022; 126:8080-8093. [PMID: 36194765 DOI: 10.1021/acs.jpcb.2c05010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The zwitterionic l-tripeptide glycylphenylalanylglycine self-assembles into very long crystalline fibrils in an aqueous solution, which causes the formation of an exceptionally strong gel phase (G' ∼ 5 × 106 Pa). The Rietveld refinement analysis of its powder X-ray diffraction (PXRD) pattern reveals a unit cell with four peptides forming a P212121 space group and adopting an inverse polyproline II conformation, that is, a right-handed helical structure that occupies the "forbidden" region of the Ramachandran plot. This unusual structure is stabilized by a plethora of intermolecular interactions facilitated by the large number of different functional groups of the unblocked tripeptide. Comparisons of simulated and experimental Fourier transform infrared and vibrational circular dichroism (VCD) amide I' profiles corroborate the PXRD structure. Our experimental setup reduces the sample to a quasi-two-dimensional network of fibrils. We exploited the influence of this reduced dimensionality on the amide I VCD to identify the main fibril axis. We demonstrate that PXRD, vibrational spectroscopy, and amide I simulations provide a powerful toolset for secondary structure and fibril axis determination.
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Affiliation(s)
- Nichole O'Neill
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States.,Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Thamires A Lima
- Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Fabio Furlan Ferreira
- Center for Natural and Human Sciences (CCNH), Federal University of ABC (UFABC), Av. Dos Estados, 5001, S622-3, Santo André, São Paulo09210-580, Brazil
| | - Lavenia Thursch
- Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Nicolas Alvarez
- Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Reinhard Schweitzer-Stenner
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
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6
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Schweitzer-Stenner R, Alvarez NJ. Short Peptides as Tunable, Switchable, and Strong Gelators. J Phys Chem B 2021; 125:6760-6775. [PMID: 34133176 DOI: 10.1021/acs.jpcb.1c01447] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This Perspective outlines our current understanding of molecular gels composed of short and ultrashort peptides over the past 20 years. We discuss in detail the state of the art regarding self-assembly mechanisms, structure, thermal stability, and kinetics of fibril and/or network formation. Emphasis is put on the importance of the combined use of spectroscopy and rheology for characterizing and validating self-assembly models. While a range of peptide chemistries are reviewed, we focus our discussion on a unique new class of ultrashort peptide gelators, denoted GxG peptides (x: guest residue), which are capable of forming self-assembled fibril networks. The storage moduli of GxG gels are tunable up to 100 kPa depending on concentration, pH, and/or cosolvent. The sheet structures of the fibrils differ from canonical β-sheets. When appropriate, each section highlights opportunities for additional research and technologies that would further our understanding.
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7
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Hesser M, Thursch LJ, Lewis TR, Lima TA, Alvarez NJ, Schweitzer-Stenner R. Concentration Dependence of a Hydrogel Phase Formed by the Deprotonation of the Imidazole Side Chain of Glycylhistidylglycine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6935-6946. [PMID: 34077210 DOI: 10.1021/acs.langmuir.1c00382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Upon deprotonation of its imidazole group at ∼pH 6, the unblocked tripeptide glycylhistidylglycine (GHG) self-assembles into very long crystalline fibrils on a 10-1000 μm scale which are capable of forming a volume spanning network, that is, hydrogel. The critical peptide concentration for self-assembly at a pH of 6 lies between 50 and 60 mM. The fraction of peptides that self-assemble into fibrils depends on the concentration of deprotonated GHG. While IR spectra seem to indicate the formation of fibrils with standard amyloid fibril β-sheet structures, vibrational circular dichroism spectra show a strongly enhanced amide I' signal, suggesting that the formed fibrils exhibit significant chirality. The fibril chirality appears to be a function of peptide concentration. Rheological measurements reveal that the rate of gelation is concentration-dependent and that there is an optimum gel strength at intermediate peptide concentrations of ca. 175 mM. This paper outlines the unique properties of the GHG gel phase which is underlain by a surprisingly dense fibril network with an exceptionally strong modulus that make them potential additives for biomedical applications.
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Affiliation(s)
- Morgan Hesser
- Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Lavenia J Thursch
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Todd R Lewis
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Thamires A Lima
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Nicolas J Alvarez
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
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8
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Vosough F, Barth A. Characterization of Homogeneous and Heterogeneous Amyloid-β42 Oligomer Preparations with Biochemical Methods and Infrared Spectroscopy Reveals a Correlation between Infrared Spectrum and Oligomer Size. ACS Chem Neurosci 2021; 12:473-488. [PMID: 33455165 PMCID: PMC8023574 DOI: 10.1021/acschemneuro.0c00642] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
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Soluble oligomers of the amyloid-β(1-42)
(Aβ42) peptide,
widely considered to be among the relevant neurotoxic species involved
in Alzheimer’s disease, were characterized with a combination
of biochemical and biophysical methods. Homogeneous and stable Aβ42
oligomers were prepared by treating monomeric solutions of the peptide
with detergents. The prepared oligomeric solutions were analyzed with
blue native and sodium dodecyl sulfate polyacrylamide gel electrophoresis,
as well as with infrared (IR) spectroscopy. The IR spectra indicated
a well-defined β-sheet structure of the prepared oligomers.
We also found a relationship between the size/molecular weight of
the Aβ42 oligomers and their IR spectra: The position of the
main amide I′ band of the peptide backbone correlated with
oligomer size, with larger oligomers being associated with lower wavenumbers.
This relationship explained the time-dependent band shift observed
in time-resolved IR studies of Aβ42 aggregation in the absence
of detergents, during which the oligomer size increased. In addition,
the bandwidth of the main IR band in the amide I′ region was
found to become narrower with time in our time-resolved aggregation
experiments, indicating a more homogeneous absorption of the β-sheets
of the oligomers after several hours of aggregation. This is predominantly
due to the consumption of smaller oligomers in the aggregation process.
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Affiliation(s)
- Faraz Vosough
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm SE-106 91, Sweden
| | - Andreas Barth
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm SE-106 91, Sweden
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Basu A, Vaskevich A, Chuntonov L. Glutathione Self-Assembles into a Shell of Hydrogen-Bonded Intermolecular Aggregates on "Naked" Silver Nanoparticles. J Phys Chem B 2021; 125:895-906. [PMID: 33440116 DOI: 10.1021/acs.jpcb.0c10089] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A detailed understanding of the molecular structure in nanoparticle ligand capping layers is crucial for their efficient incorporation into modern scientific and technological applications. Peptide ligands render the nanoparticles as biocompatible materials. Glutathione, a γ-ECG tripeptide, self-assembles into aggregates on the surface of ligand-free silver nanoparticles through intermolecular hydrogen bonding and forms a few nanometer-thick shells. Two-dimensional nonlinear infrared (2DIR) spectroscopy suggests that aggregates adopt a conformation resembling the β-sheet secondary structure. The shell thickness was evaluated with localized surface plasmon resonance spectroscopy and X-ray photoelectron spectroscopy. The amount of glutathione on the surface was obtained with spectrophotometry of a thiol-reactive probe. Our results suggest that the shell consists of ∼15 stacked molecular layers. These values correspond to the inter-sheet distances, which are significantly shorter than those in amyloid fibrils with relatively bulky side chains, but are comparable to glycine-rich silk fibrils, where the side chains are compact. The tight packing of the glutathione layers can be facilitated by hydrogen-bonded carboxylic acid dimers of glycine and the intermolecular salt bridges between the zwitterionic γ-glutamyl groups. The structure of the glutathione aggregates was studied by 2DIR spectroscopy of the amide-I vibrational modes using 13C isotope labeling of the cysteine carbonyl. Isotope dilution experiments revealed the coupling of modes forming vibrational excitons along the cysteine chain. The coupling along the γ-glutamyl exciton chain was estimated from these values. The obtained coupling strengths are slightly lower than those of native β-sheets, yet they appear large enough to point onto an ordered conformation of the peptides within the aggregate. Analysis of the excitons' anharmonicities and the strength of the transition dipole moments generally is in agreement with these observations.
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Affiliation(s)
- Arghyadeep Basu
- Schulich Faculty of Chemistry and Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Alexander Vaskevich
- Department of Materials and Interfaces, and Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Lev Chuntonov
- Schulich Faculty of Chemistry and Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
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Tseng WH, Chen SH, Hiramatsu H. pH-controlled stacking direction of the β-strands in peptide fibrils. Sci Rep 2020; 10:22199. [PMID: 33335192 PMCID: PMC7747703 DOI: 10.1038/s41598-020-79001-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/11/2020] [Indexed: 12/11/2022] Open
Abstract
Peptides provide a framework for generating functional biopolymers. In this study, the pH-dependent structural changes in the 21-29 fragment peptide of β2-microglobulin (β2m21-29) during self-aggregation, i.e., the formation of an amyloid fibril, were discussed. The β-sheet structures formed during parallel stacking under basic conditions (pH ≥ 7.7) adopted an anti-parallel stacking configuration under acidic conditions (pH ≤ 7.6). The parallel and anti-parallel β-sheets existed separately at the intermediate pH (pH = 7.6-7.7). These results were attributed to the rigidity of the β-sheets in the fibrils, which prevented the stable hydrogen bonding interactions between the parallel and anti-parallel β-sheet moieties. This observed pH dependence was ascribed to two phenomena: (i) the pH-dependent collapse of the β2m21-29 fibrils, which consisted of 16 ± 3 anti-parallel β-sheets containing a total of 2000 β-strands during the deprotonation of the NH3+ group (pKa = 8.0) of the β-strands that occurred within 0.7 ± 0.2 strands of each other and (ii) the subsequent formation of the parallel β-sheets. We propose a framework for a functional biopolymer that could alternate between the two β-sheet structures in response to pH changes.
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Affiliation(s)
- Wei-Hsuan Tseng
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu, 30010, Taiwan
| | - Szu-Hua Chen
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu, 30010, Taiwan
| | - Hirotsugu Hiramatsu
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu, 30010, Taiwan.
- Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, 30010, Taiwan.
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On the Secondary Structure of Silk Fibroin Nanoparticles Obtained Using Ionic Liquids: An Infrared Spectroscopy Study. Polymers (Basel) 2020; 12:polym12061294. [PMID: 32516911 PMCID: PMC7361871 DOI: 10.3390/polym12061294] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 05/27/2020] [Accepted: 06/02/2020] [Indexed: 12/30/2022] Open
Abstract
Silk fibroin from Bombyx mori caterpillar is an outstanding biocompatible polymer for the production of biomaterials. Its impressive combination of strength, flexibility, and degradability are related to the protein’s secondary structure, which may be altered during the manufacture of the biomaterial. The present study looks at the silk fibroin secondary structure during nanoparticle production using ionic liquids and high-power ultrasound using novel infrared spectroscopic approaches. The infrared spectrum of silk fibroin fibers shows that they are composed of 58% β-sheet, 9% turns, and 33% irregular and/or turn-like structures. When fibroin was dissolved in ionic liquids, its amide I band resembled that of soluble silk and no β-sheet absorption was detected. Silk fibroin nanoparticles regenerated from the ionic liquid solution exhibited an amide I band that resembled that of the silk fibers but had a reduced β-sheet content and a corresponding higher content of turns, suggesting an incomplete turn-to-sheet transition during the regeneration process. Both the analysis of the experimental infrared spectrum and spectrum calculations suggest a particular type of β-sheet structure that was involved in this deficiency, whereas the two other types of β-sheet structure found in silk fibroin fibers were readily formed.
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12
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Inhibiting and catalysing amyloid fibrillation at dynamic lipid interfaces. J Colloid Interface Sci 2019; 543:256-262. [PMID: 30818141 DOI: 10.1016/j.jcis.2019.02.072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/30/2019] [Accepted: 02/21/2019] [Indexed: 11/20/2022]
Abstract
Proteins are naturally exposed to diverse interfaces in living organisms, from static solid to dynamic fluid. Solid interfaces can enrich proteins as corona, and then catalyze, retard or hinder amyloid fibrillation. But fluid interfaces abundant in biology have rarely been studied for their correlation with protein fibrillation. Unsaturated fatty acids own growing essential roles in diet, whose fluid interfaces are found in vitro to catalyze amyloid fibrillation under certain physiologic conditions. It is determined by the location of double bonds within alkyl chains as well as the presence of physical shear. Docosahexaenoic acid (DHA) shows low catalysis because its unique alkyl chain does not favor to stabilize cross-β nucleus. Mixtures of different fatty acids also decelerate their catalytic activity. High catalysis poses an unprecedented approach to synthesize biologic nanofibrils as one-dimensional (1D) building blocks of functional hybrids. Fibrillation inhibition implied that appropriate diet would be a preventive strategy for amyloid-related diseases. Thus these results may find their significances in diverse fields of science as chemistry, biotechnology, nanotechnology, nutrition, amyloid pathobiology and nanomedicine.
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Abstract
Fourier transform infrared (FTIR) spectroscopy has become one of the major techniques of structural characterization of proteins, peptides, and protein-membrane interactions. While the method does not have the capability of providing the precise, atomic-resolution molecular structure, it is exquisitely sensitive to conformational changes occurring in proteins upon functional transitions or intermolecular interactions. The sensitivity of vibrational frequencies to atomic masses has led to development of "isotope-edited" FTIR spectroscopy, where structural effects in two proteins, one unlabeled and the other labeled with a heavier stable isotope, such as 13C, are resolved simultaneously based on spectral downshift (separation) of the amide I band of the labeled protein. The same isotope effect is used to identify site-specific conformational changes in proteins by site-directed or segmental isotope labeling. Negligible light scattering in the infrared region provides an opportunity to study intermolecular interactions between large protein complexes, interactions of proteins and peptides with lipid vesicles, or protein-nucleic acid interactions without light scattering problems often encountered in ultraviolet spectroscopy. Attenuated total reflection FTIR (ATR-FTIR) is a surface-sensitive version of infrared spectroscopy that has proved useful in studying membrane proteins and lipids, protein-membrane interactions, mechanisms of interfacial enzymes, the structural features of membrane pore forming proteins and peptides, and much more. The purpose of this chapter was to provide a practical guide to analyze protein structure and protein-membrane interactions by FTIR and ATR-FTIR techniques, including procedures of sample preparation, measurements, and data analysis. Basic background information on FTIR spectroscopy, as well as some relatively new developments in structural and functional characterization of proteins and peptides in lipid membranes, is also presented.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
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14
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Zn 2+-triggered self-assembly of Gonadorelin [6-D-Phe] to produce nanostructures and fibrils. Sci Rep 2018; 8:11280. [PMID: 30050082 PMCID: PMC6062538 DOI: 10.1038/s41598-018-29529-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 07/12/2018] [Indexed: 12/23/2022] Open
Abstract
A synthetic derivative, GnRH [6-D-Phe], stable against enzymatic degradation, self-assembles and forms nanostructures and fibrils upon a pH shift in the presence of different concentrations of Zn2+in vitro. Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR–FTIR) revealed the existence of higher order assembly of Zn2+: GnRH [6-D-Phe]. Nuclear Magnetic Resonance spectroscopy (NMR) indicated a weak interaction between Zn2+ and GnRH [6-D-Phe]. Atomic Force Microscopy (AFM) showed the existence of GnRH [6-D-Phe] oligomers and fibrils. Molecular Dynamic (MD) simulation of the 10:1 Zn2+: GnRH [6-D-Phe] explored the interaction and dimerization processes. In contrast to already existing short peptide fibrils, GnRH [6-D-Phe] nanostructures and fibrils form in a Tris-buffered pH environment in a controlled manner through a temperature reduction and a pH shift. The lyophilized Zn2+: GnRH [6-D-Phe] assembly was tested as a platform for the sustained delivery of GnRH [6-D-Phe] and incorporated into two different oil vehicle matrices. The in vitro release was slow and continuous over 14 days and not influenced by the oil matrix.
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15
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Abstract
Attenuated total reflection FTIR (ATR-FTIR) has been used for decades to study protein secondary structures. More recently, it reveals also to be an exquisite and sensitive tool to study and discriminate amyloid aggregates. Based on the analysis of specific spectral features of β-sheet structures, we present here a detailed protocol to differentiate oligomers vs. fibrils. This protocol, applicable to all amyloid proteins, demonstrates the power of this inexpensive, rapid, and low protein material-demanding method.
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Affiliation(s)
- Jean-Marie Ruysschaert
- Faculty of Science, Laboratory of Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium
| | - Vincent Raussens
- Faculty of Science, Laboratory of Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium.
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16
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Roeters SJ, Iyer A, Pletikapić G, Kogan V, Subramaniam V, Woutersen S. Evidence for Intramolecular Antiparallel Beta-Sheet Structure in Alpha-Synuclein Fibrils from a Combination of Two-Dimensional Infrared Spectroscopy and Atomic Force Microscopy. Sci Rep 2017; 7:41051. [PMID: 28112214 PMCID: PMC5253669 DOI: 10.1038/srep41051] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/12/2016] [Indexed: 12/13/2022] Open
Abstract
The aggregation of the intrinsically disordered protein alpha-synuclein (αS) into amyloid fibrils is thought to play a central role in the pathology of Parkinson’s disease. Using a combination of techniques (AFM, UV-CD, XRD, and amide-I 1D- and 2D-IR spectroscopy) we show that the structure of αS fibrils varies as a function of ionic strength: fibrils aggregated in low ionic-strength buffers ([NaCl] ≤ 25 mM) have a significantly different structure than fibrils grown in higher ionic-strength buffers. The observations for fibrils aggregated in low-salt buffers are consistent with an extended conformation of αS molecules, forming hydrogen-bonded intermolecular β-sheets that are loosely packed in a parallel fashion. For fibrils aggregated in high-salt buffers (including those prepared in buffers with a physiological salt concentration) the measurements are consistent with αS molecules in a more tightly-packed, antiparallel intramolecular conformation, and suggest a structure characterized by two twisting stacks of approximately five hydrogen-bonded intermolecular β-sheets each. We find evidence that the high-frequency peak in the amide-I spectrum of αS fibrils involves a normal mode that differs fundamentally from the canonical high-frequency antiparallel β-sheet mode. The high sensitivity of the fibril structure to the ionic strength might form the basis of differences in αS-related pathologies.
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Affiliation(s)
- Steven J Roeters
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Aditya Iyer
- Nanoscale Biophysics Group, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Galja Pletikapić
- Nanoscale Biophysics Group, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Vladimir Kogan
- Dannalab BV, Wethouder Beversstraat 185, 7543 BK Enschede, The Netherlands
| | - Vinod Subramaniam
- Nanoscale Biophysics Group, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.,Vrije Universiteit Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands
| | - Sander Woutersen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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17
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Iyer A, Roeters SJ, Schilderink N, Hommersom B, Heeren RMA, Woutersen S, Claessens MMAE, Subramaniam V. The Impact of N-terminal Acetylation of α-Synuclein on Phospholipid Membrane Binding and Fibril Structure. J Biol Chem 2016; 291:21110-21122. [PMID: 27531743 PMCID: PMC5076520 DOI: 10.1074/jbc.m116.726612] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 11/29/2022] Open
Abstract
Human α-synuclein (αS) has been shown to be N terminally acetylated in its physiological state. This modification is proposed to modulate the function and aggregation of αS into amyloid fibrils. Using bacterially expressed acetylated-αS (NTAc-αS) and endogenous αS (Endo-αS) from human erythrocytes, we show that N-terminal acetylation has little impact on αS binding to anionic membranes and thus likely not relevant for regulating membrane affinity. N-terminal acetylation does have an effect on αS aggregation, resulting in a narrower distribution of the aggregation lag times and rates. 2D-IR spectra show that acetylation changes the secondary structure of αS in fibrils. This difference may arise from the slightly higher helical propensity of acetylated-αS in solution leading to a more homogenous fibril population with different fibril structure than non-acetylated αS. We speculate that N-terminal acetylation imposes conformational restraints on N-terminal residues in αS, thus predisposing αS toward specific interactions with other binding partners or alternatively decrease nonspecific interactions.
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Affiliation(s)
- Aditya Iyer
- From the Nanoscale Biophysics Group, FOM Institute AMOLF, Amsterdam, the Nanobiophysics Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede
| | - Steven J Roeters
- the Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam
| | - Nathalie Schilderink
- the Nanobiophysics Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede
| | - Bob Hommersom
- the BioImaging MS Group, FOM Institute AMOLF, Amsterdam, The Netherlands
| | - Ron M A Heeren
- the BioImaging MS Group, FOM Institute AMOLF, Amsterdam, The Netherlands, the M4I, The Maastricht MultiModal Molecular Imaging Institute, University of Maastricht, and
| | - Sander Woutersen
- the Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam,
| | | | - Vinod Subramaniam
- From the Nanoscale Biophysics Group, FOM Institute AMOLF, Amsterdam, the Nanobiophysics Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Vrije Universiteit Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands
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18
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Edington SC, Flanagan JC, Baiz CR. An Empirical IR Frequency Map for Ester C═O Stretching Vibrations. J Phys Chem A 2016; 120:3888-96. [DOI: 10.1021/acs.jpca.6b02887] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sean C. Edington
- Department
of Chemistry, University of Texas at Austin, 105 E. 24th St. Stop A5300, Austin, Texas 78712-1224, United States
| | - Jennifer C. Flanagan
- Department
of Chemistry, University of Texas at Austin, 105 E. 24th St. Stop A5300, Austin, Texas 78712-1224, United States
| | - Carlos R. Baiz
- Department
of Chemistry, University of Texas at Austin, 105 E. 24th St. Stop A5300, Austin, Texas 78712-1224, United States
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19
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Baldassarre M, Bennett M, Barth A. Simultaneous acquisition of infrared, fluorescence and light scattering spectra of proteins: direct evidence for pre-fibrillar species in amyloid fibril formation. Analyst 2016; 141:963-73. [PMID: 26668843 DOI: 10.1039/c5an02283e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Different spectroscopic approaches are often used to probe specific aspects of amyloid fibril formation but are usually performed separately and under different conditions. This makes it problematic to relate different aspects of the aggregation process when these are monitored by different methods. We report on a multispectral approach for simultaneous acquisition of infrared, fluorescence and light scattering spectra of proteins undergoing aggregation. We have applied our approach to study β-lactoglobulin, a milk protein known to form amyloid fibrils under well-established conditions. Our real-time multispectral measurements show that unfolding of this protein is followed by formation of early aggregates consisting of intermolecular β-sheets with a typical infrared absorption at ∼1619 cm(-1) in (2)H2O. These aggregates, which lead to an increase in the light scattering signal, do not bind the amyloid-specific fluorophore ThT and therefore consist of oligomers or protofibrils. Fibril growth is then observed as a sigmoidal increase in ThT fluorescence. After ∼25 h, a plateau is observed in the intensities of ThT emission and of the band at 1619 cm(-1), indicating that no new fibrils are forming. However, a second phase in the light scattering signal taking place after ∼25 h suggests that the fibrils are assembling into larger structures, known as mature fibrils. This is associated with an upshift of the main β-sheet band in the infrared spectrum. TEM analyses confirmed the existence of thick fibrils comprising 3-5 filaments.
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Affiliation(s)
- Maurizio Baldassarre
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
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20
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Baldassarre M, Li C, Eremina N, Goormaghtigh E, Barth A. Simultaneous Fitting of Absorption Spectra and Their Second Derivatives for an Improved Analysis of Protein Infrared Spectra. Molecules 2015; 20:12599-622. [PMID: 26184143 PMCID: PMC6331840 DOI: 10.3390/molecules200712599] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/06/2015] [Accepted: 07/07/2015] [Indexed: 02/06/2023] Open
Abstract
Infrared spectroscopy is a powerful tool in protein science due to its sensitivity to changes in secondary structure or conformation. In order to take advantage of the full power of infrared spectroscopy in structural studies of proteins, complex band contours, such as the amide I band, have to be decomposed into their main component bands, a process referred to as curve fitting. In this paper, we report on an improved curve fitting approach in which absorption spectra and second derivative spectra are fitted simultaneously. Our approach, which we name co-fitting, leads to a more reliable modelling of the experimental data because it uses more spectral information than the standard approach of fitting only the absorption spectrum. It also avoids that the fitting routine becomes trapped in local minima. We have tested the proposed approach using infrared absorption spectra of three mixed α/β proteins with different degrees of spectral overlap in the amide I region: ribonuclease A, pyruvate kinase, and aconitase.
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Affiliation(s)
- Maurizio Baldassarre
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.
| | - Chenge Li
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.
| | - Nadejda Eremina
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.
| | - Erik Goormaghtigh
- Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, 1050 Brussels, Belgium.
| | - Andreas Barth
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.
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21
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Daidone I, Thukral L, Smith JC, Amadei A. Monitoring the Folding Kinetics of a β-Hairpin by Time-Resolved IR Spectroscopy in Silico. J Phys Chem B 2015; 119:4849-56. [DOI: 10.1021/acs.jpcb.5b01477] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Isabella Daidone
- Department
of Physical and Chemical Sciences, University of L’Aquila, via
Vetoio (Coppito 1), 67010 L’Aquila, Italy
| | - Lipi Thukral
- CSIR-Institute of Genomics and Integrative Biology, South Campus, Mathura Road, New Delhi 110020, India
| | - Jeremy C. Smith
- University of Tennessee/Oak Ridge National Laboratory, Center for Molecular Biophysics, P.O. Box 2008, Oak Ridge, Tennessee 37831-6309, United States
- Department
of Biochemistry and Cellular and Molecular Biology, University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, Tennessee 37996, United States
| | - Andrea Amadei
- Department
of Chemical Sciences and Technologies, University of Rome “Tor Vergata”, via della Ricerca Scientifica 1, 00133 Rome, Italy
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22
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Kessler J, Keiderling TA, Bouř P. Arrangement of Fibril Side Chains Studied by Molecular Dynamics and Simulated Infrared and Vibrational Circular Dichroism Spectra. J Phys Chem B 2014; 118:6937-45. [DOI: 10.1021/jp502178d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jiří Kessler
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences, Flemingovo
náměstí 2, 166
10 Prague, Czech Republic
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 40 Prague, Czech Republic
| | - Timothy A. Keiderling
- Department
of Chemistry, University of Illinois at Chicago, 845 West Taylor
Street, Chicago, Illinois 60607-7061, United States
| | - Petr Bouř
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences, Flemingovo
náměstí 2, 166
10 Prague, Czech Republic
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23
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Małolepsza E, Straub JE. Empirical maps for the calculation of amide I vibrational spectra of proteins from classical molecular dynamics simulations. J Phys Chem B 2014; 118:7848-55. [PMID: 24654732 PMCID: PMC4317051 DOI: 10.1021/jp412827s] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
New sets of parameters (maps) for
calculating amide I vibrational
spectra for proteins through a vibrational exciton model are proposed.
The maps are calculated as a function of electric field and van der
Waals forces on the atoms of peptide bonds, taking into account the
full interaction between peptide bonds and the surrounding environment.
The maps are designed to be employed using data obtained from standard
all-atom molecular simulations without any additional constraints
on the system. Six proteins representing a wide range of sizes and
secondary structure complexity were chosen as a test set. Spectra
calculated for these proteins reproduce experimental data both qualitatively
and quantitatively. The proposed maps lead to spectra that capture
the weak second peak observed in proteins containing β-sheets,
allowing for clear distinction between α-helical and β-sheet
proteins. While the parametrization is specific to the CHARMM force
field, the methodology presented can be readily applied to any empirical
force field.
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Affiliation(s)
- Edyta Małolepsza
- Department of Chemistry, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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24
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Chi H, Welch WRW, Kubelka J, Keiderling TA. Insight into the Packing Pattern of β2 Fibrils: A Model Study of Glutamic Acid Rich Oligomers with 13C Isotopic Edited Vibrational Spectroscopy. Biomacromolecules 2013; 14:3880-91. [DOI: 10.1021/bm401015f] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Heng Chi
- Department
of Chemistry, University of Illinois at Chicago, 845 West Taylor
Street (m/c111), Chicago, Illinois 60607-7061, United States
| | - William R. W. Welch
- Department
of Chemistry, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Jan Kubelka
- Department
of Chemistry, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Timothy A. Keiderling
- Department
of Chemistry, University of Illinois at Chicago, 845 West Taylor
Street (m/c111), Chicago, Illinois 60607-7061, United States
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25
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Welch WRW, Kubelka J, Keiderling TA. Infrared, vibrational circular dichroism, and Raman spectral simulations for β-sheet structures with various isotopic labels, interstrand, and stacking arrangements using density functional theory. J Phys Chem B 2013; 117:10343-58. [PMID: 23924300 DOI: 10.1021/jp4056126] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Infrared (IR), Raman, and vibrational circular dichroism (VCD) spectral variations for different β-sheet structures were studied using simulations based on density functional theory (DFT) force field and intensity computations. The DFT vibrational parameters were obtained for β-sheet fragments containing nine-amides and constrained to a variety of conformations and strand arrangements. These were subsequently transferred onto corresponding larger β-sheet models, normally consisting of five strands with ten amides each, for spectral simulations. Further extension to fibril models composed of multiple stacked β-sheets was achieved by combining the transfer of DFT parameters for each sheet with dipole coupling methods for interactions between sheets. IR spectra of the amide I show different splitting patterns for parallel and antiparallel β-sheets, and their VCD, in the absence of intersheet stacking, have distinct sign variations. Isotopic labeling by (13)C of selected residues yields spectral shifts and intensity changes uniquely sensitive to relative alignment of strands (registry) for antiparallel sheets. Stacking of multiple planar sheets maintains the qualitative spectral character of the single sheet but evidences some reduction in the exciton splitting of the amide I mode. Rotating sheets with respect to each other leads to a significant VCD enhancement, whose sign pattern and intensity is dependent on the handedness and degree of rotation. For twisted β-sheets, a significant VCD enhancement is computed even for sheets stacked with either the same or opposite alignments and the inter-sheet rotation, depending on the sense, can either further increase or weaken the enhanced VCD intensity. In twisted, stacked structures (without rotation), similar VCD amide I patterns (positive couplets) are predicted for both parallel and antiparallel sheets, but different IR intensity distributions still enable their differentiation. Our simulation results prove useful for interpreting experimental vibrational spectra in terms of β-sheet and fibril structure, as illustrated in the accompanying paper.
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Affiliation(s)
- William R W Welch
- Department of Chemistry, University of Wyoming , Laramie, Wyoming 82071, United States
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26
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Welch WRW, Keiderling TA, Kubelka J. Structural analyses of experimental 13C edited amide I' IR and VCD for peptide β-sheet aggregates and fibrils using DFT-based spectral simulations. J Phys Chem B 2013; 117:10359-69. [PMID: 23924239 DOI: 10.1021/jp405613r] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the preceding paper, computational models based on density functional theory (DFT) were presented to characterize the sensitivity of vibrational spectroscopic methods (IR, VCD, and Raman) to structural features of β-sheets. Isotopically edited amide I' IR for peptides labeled with (13)C in multiple different sites provides the most structurally distinct signatures of strand alignment, while VCD is sensitive to the sheet twist and intersheet stacking. In this report, we simulate the IR and VCD spectra for models approximating structures of four β-sheet forming peptides previously experimentally studied using these methods with (13)C isotopic editing. Various register alignments are tested. Agreement with experiment is evaluated based on frequency shifts of both the (12)C and (13)C IR amide I' signals, relative intensity patterns, and VCD spectra where available. While for the simulation of IR spectra canonical planar sheets provide a sufficient model system, for VCD simulation twisted, stacked sheets are required in order to reproduce strong couplet-like amide I' VCD. Effects of the solvent (water) and amino acid side chains are also tested by using a simplified, electrostatic solvent model and atomic partial charges for the side chains. Very good agreement with experimental spectra is obtained, particularly for the relative (12)C and (13)C band frequencies. All four peptide models are shown to be antiparallel as had previously been assumed. However, in some cases our simulations are consistent with different register alignment of strands than originally proposed.
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Affiliation(s)
- William R W Welch
- Department of Chemistry, University of Wyoming , Laramie, Wyoming 82071, United States
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27
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Fabian H, Gast K, Laue M, Jetzschmann KJ, Naumann D, Ziegler A, Uchanska-Ziegler B. IR spectroscopic analyses of amyloid fibril formation of β2-microglobulin using a simplified procedure for its in vitro generation at neutral pH. Biophys Chem 2013; 179:35-46. [PMID: 23727989 DOI: 10.1016/j.bpc.2013.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 04/29/2013] [Accepted: 05/01/2013] [Indexed: 11/16/2022]
Abstract
β2-microglobulin (β2m) is known to be the major component of fibrillar deposits in the joints of patients suffering from dialysis-related amyloidosis. We have developed a simplified procedure to convert monomeric recombinant β2m into amyloid fibrils at physiological pH by a combination of stirring and heating, enabling us to follow conformational changes associated with the assembly by infrared spectroscopy and electron microscopy. Our studies reveal that fibrillogenesis begins with the formation of relatively large aggregates, with secondary structure not significantly altered by the stirring-induced association. In contrast, the conversion of the amorphous aggregates into amyloid fibrils is associated with a profound re-organization at the level of the secondary and tertiary structures, leading to non-native like parallel arrangements of the β-strands in the fully formed amyloid structure of β2m. This study highlights the power of an approach to investigate the formation of β2m fibrils by a combination of biophysical techniques including IR spectroscopy.
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Affiliation(s)
- Heinz Fabian
- Robert Koch-Institut, ZBS 6, Nordufer 20, D-13353 Berlin, Germany.
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28
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Tatulian SA. Structural characterization of membrane proteins and peptides by FTIR and ATR-FTIR spectroscopy. Methods Mol Biol 2013; 974:177-218. [PMID: 23404277 DOI: 10.1007/978-1-62703-275-9_9] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Fourier transform infrared (FTIR) spectroscopy is widely used in structural characterization of proteins or peptides. While the method does not have the capability of providing the precise, atomic-resolution molecular structure, it is exquisitely sensitive to conformational changes occurring in proteins upon functional transitions or upon intermolecular interactions. Sensitivity of vibrational frequencies to atomic masses has led to development of "isotope-edited" FTIR spectroscopy, where structural effects in two proteins, one unlabeled and the other labeled with a heavier stable isotope, such as (13)C, are resolved simultaneously based on spectral downshift (separation) of the amide I band of the labeled protein. The same isotope effect is used to identify site-specific conformational changes in proteins by site-directed or segmental isotope labeling. Negligible light scattering in the infrared region provides an opportunity to study intermolecular interactions between large protein complexes, interactions of proteins and peptides with lipid vesicles, or protein-nucleic acid interactions without light scattering problems often encountered in ultraviolet spectroscopy. Attenuated total reflection FTIR (ATR-FTIR) is a surface-sensitive version of infrared spectroscopy that has proved useful in studying membrane proteins and lipids, protein-membrane interactions, mechanisms of interfacial enzymes, and molecular architecture of membrane pore or channel forming proteins and peptides. The purpose of this article was to provide a practical guide to analyze protein structure and protein-membrane interactions by FTIR and ATR-FTIR techniques, including procedures of sample preparation, measurements, and data analysis. Basic background information on FTIR spectroscopy, as well as some relatively new developments in structural and functional characterization of proteins and peptides in lipid membranes, are also presented.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
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29
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Kawasaki T, Fujioka J, Imai T, Tsukiyama K. Effect of mid-infrared free-electron laser irradiation on refolding of amyloid-like fibrils of lysozyme into native form. Protein J 2012; 31:710-6. [PMID: 23054332 PMCID: PMC3483483 DOI: 10.1007/s10930-012-9452-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Aggregation of lysozyme in an acidic solution generates inactive amyloid-like fibrils, with a broad infrared peak appearing at 1,610-1,630 cm(-1), characteristic of a β-sheet rich structure. We report here that spontaneous refolding of these fibrils in water could be promoted by mid-infrared free-electron laser (mid-IR FEL) irradiation targeting the amide bands. The Fourier transform infrared spectrum of the fibrils reflected a β-sheet content that was as low as that of the native structure, following FEL irradiation at 1,620 cm(-1) (amide I band); both transmission-electron microscopy imaging and Congo Red assay results also demonstrated a reduced fibril structure, and the enzymatic activity of lysozyme fibrils recovered to 70-90 % of the native form. Both irradiations at 1,535 cm(-1)(amide II band) and 1,240 cm(-1) (amide III band) were also more effective for the refolding of the fibrils than mere heating in the absence of FEL. On the contrary, either irradiation at 1,100 or 2,000 cm(-1) afforded only about 60 % recovery of lysozyme activity. These results indicate that the specific FEL irradiation tuned to amide bands is efficient in refolding of lysozyme fibrils into native form.
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Affiliation(s)
- Takayasu Kawasaki
- IR Free Electron Laser Research Center, Research Institute for Science and Technology (RIST), Tokyo University of Science, Yamazaki, Noda, Chiba, Japan.
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30
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Woys AM, Almeida AM, Wang L, Chiu CC, McGovern M, de Pablo JJ, Skinner JL, Gellman SH, Zanni MT. Parallel β-sheet vibrational couplings revealed by 2D IR spectroscopy of an isotopically labeled macrocycle: quantitative benchmark for the interpretation of amyloid and protein infrared spectra. J Am Chem Soc 2012; 134:19118-28. [PMID: 23113791 DOI: 10.1021/ja3074962] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Infrared spectroscopy is playing an important role in the elucidation of amyloid fiber formation, but the coupling models that link spectra to structure are not well tested for parallel β-sheets. Using a synthetic macrocycle that enforces a two stranded parallel β-sheet conformation, we measured the lifetimes and frequency for six combinations of doubly (13)C═(18)O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequencies of the labels ranged from 1585 to 1595 cm(-1), with the largest frequency shift occurring for in-register amino acids. The 2D IR spectra of the coupled isotope labels were calculated from molecular dynamics simulations of a series of macrocycle structures generated from replica exchange dynamics to fully sample the conformational distribution. The models used to simulate the spectra include through-space coupling, through-bond coupling, and local frequency shifts caused by environment electrostatics and hydrogen bonding. The calculated spectra predict the line widths and frequencies nearly quantitatively. Historically, the characteristic features of β-sheet infrared spectra have been attributed to through-space couplings such as transition dipole coupling. We find that frequency shifts of the local carbonyl groups due to nearest neighbor couplings and environmental factors are more important, while the through-space couplings dictate the spectral intensities. As a result, the characteristic absorption spectra empirically used for decades to assign parallel β-sheet secondary structure arises because of a redistribution of oscillator strength, but the through-space couplings do not themselves dramatically alter the frequency distribution of eigenstates much more than already exists in random coil structures. Moreover, solvent exposed residues have amide I bands with >20 cm(-1) line width. Narrower line widths indicate that the amide I backbone is solvent protected inside the macrocycle. This work provides calculated and experimentally verified couplings for parallel β-sheets that can be used in structure-based models to simulate and interpret the infrared spectra of β-sheet containing proteins and protein assemblies, such as amyloid fibers.
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Affiliation(s)
- Ann Marie Woys
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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Faller P, Hureau C, Dorlet P, Hellwig P, Coppel Y, Collin F, Alies B. Methods and techniques to study the bioinorganic chemistry of metal–peptide complexes linked to neurodegenerative diseases. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.03.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Karjalainen EL, Barth A. Vibrational coupling between helices influences the amide I infrared absorption of proteins: application to bacteriorhodopsin and rhodopsin. J Phys Chem B 2012; 116:4448-56. [PMID: 22435481 DOI: 10.1021/jp300329k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The amide I spectrum of multimers of helical protein segments was simulated using transition dipole coupling (TDC) for long-range interactions between individual amide oscillators and DFT data from dipeptides (la Cour Jansen et al. J. Chem. Phys.2006, 125, 44312) for nearest neighbor interactions. Vibrational coupling between amide groups on different helices shift the helix absorption to higher wavenumbers. This effect is small for helix dimers (1 cm(-1)) at 10 Å distance and only moderately affected by changes in the relative orientation between the helices. However, the effect becomes considerable when several helices are bundled in membrane proteins. Particular examples are the 7-helix membrane proteins bacteriorhodopsin (BR) and rhodopsin, where the upshift is 4.3 and 5.3 cm(-1), respectively, due to interhelical coupling within a BR monomer. A further upshift of 4.0 cm(-1) occurs when BR monomers associate to trimers. We propose that interhelical vibrational coupling explains the experimentally observed unusually high wavenumber of the amide I band of BR.
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Affiliation(s)
- Eeva-Liisa Karjalainen
- Department of Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, Stockholm, Sweden
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Rocha S, Loureiro JA, Brezesinski G, Pereira MDC. Peptide-surfactant interactions: consequences for the amyloid-beta structure. Biochem Biophys Res Commun 2012; 420:136-40. [PMID: 22405768 DOI: 10.1016/j.bbrc.2012.02.129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 02/22/2012] [Indexed: 12/15/2022]
Abstract
The conformation of amyloid-beta peptide (Aβ) determines if toxic aggregates are formed. The peptide structure by its turn depends on the environment and molecule-molecule interactions. We characterized the secondary structure of Aβ-(1-40) in surfactant solutions and interacting with monolayers. The peptide adopts β-sheet structure in solutions of ionic surfactants at sub-micelle concentrations and α-helix in the presence of ionic micelles. Uncharged micelles induce β-sheets. Aβ-(1-40) alters the critical micelle concentration value of the non-ionic surfactant, underlining hydrophobic interactions. At ionic monolayers the peptide forms β-sheets when its concentration at the surface is high enough. These results suggest that only electrostatic interactions of charged micelles that surround completely the peptide are able to induce non-aggregated α-helix structure.
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Affiliation(s)
- Sandra Rocha
- LEPAE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Roberto Frias, Porto, Portugal.
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Torii H, Giorgini MG, Musso M. Merged- and Separate-Band Behavior of the C═O Stretching Band in N,N-Dimethylformamide Isotopic Liquid Mixtures: DMF/DMF-d1, DMF/DMF-d6, and DMF/DMF-13C═O. J Phys Chem B 2011; 116:353-66. [DOI: 10.1021/jp209119e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hajime Torii
- Department of Chemistry, School of Education, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan
| | - Maria Grazia Giorgini
- Dipartimento di Chimica Fisica ed Inorganica, Università di Bologna, Viale del Risorgimento 4, I-40136 Bologna, Italy
| | - Maurizio Musso
- Fachbereich Materialforschung und Physik, Abteilung Physik und Biophysik, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
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Zanetti Polzi L, Daidone I, Anselmi M, Carchini G, Di Nola A, Amadei A. Analysis of Infrared Spectra of β-Hairpin Peptides As Derived from Molecular Dynamics Simulations. J Phys Chem B 2011; 115:11872-8. [DOI: 10.1021/jp202332z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
| | - Isabella Daidone
- Dipartimento di Chimica Ingegneria Chimica e Materiali, University of L′Aquila, Coppito (AQ), Italy
| | | | - Giuliano Carchini
- Dipartimento di Chimica, University of Rome “La Sapienza”, Rome, Italy
| | - Alfredo Di Nola
- Dipartimento di Chimica, University of Rome “La Sapienza”, Rome, Italy
| | - Andrea Amadei
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome “Tor Vergata”, Rome, Italy
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Cheng HM, Tsai TWT, Huang WYC, Lee HK, Lian HY, Chou FC, Mou Y, Chan JCC. Steric zipper formed by hydrophobic peptide fragment of Syrian hamster prion protein. Biochemistry 2011; 50:6815-23. [PMID: 21749158 DOI: 10.1021/bi200712z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Steric zippers, where the residues of two neighboring β-sheet layers are tightly interdigitated, have been proposed as fundamental structural units of amyloid fibrils by Eisenberg and co-workers. The steric zipper formed by polypeptides containing the palindromic sequence AGAAAAGA has a distinctive feature that the distance between two interdigitated β-sheet layers is comparable to the interstrand distance of the individual β-sheet. This structural motif is of great interest in the study of prion disease because the AGAAAAGA sequence is highly conserved in prion proteins of different species. In this work, the amyloid fibrils formed by the polypeptides of PrP(113-127), viz. Ac-AGAAAAGAVVGGLGG-NH(2), are taken as the model compound to investigate the biophysical principles governing the steric zipper formation. The target fibrils adopt the structural motif of class 7 steric zipper, which is formed by stacking of antiparallel β-sheet layers with residue 117 + k forming backbone hydrogen bonds to residue 120 - k. Implication of our results in the infectivity of scrapie prion is briefly discussed.
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Affiliation(s)
- Hsin-Mei Cheng
- Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 106, Taiwan
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Zanetti Polzi L, Amadei A, Aschi M, Daidone I. New Insight into the IR-Spectra/Structure Relationship in Amyloid Fibrils: A Theoretical Study on a Prion Peptide. J Am Chem Soc 2011; 133:11414-7. [DOI: 10.1021/ja2028662] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Laura Zanetti Polzi
- Department of Chemistry, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Andrea Amadei
- Department of Chemical Sciences and Technologies, University of Rome “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Massimiliano Aschi
- Department of Chemistry, Chemical Engineering and Materials, University of L’Aquila, Via Vetoio (Coppito 1), 67010 L’Aquila, Italy
| | - Isabella Daidone
- Department of Chemistry, Chemical Engineering and Materials, University of L’Aquila, Via Vetoio (Coppito 1), 67010 L’Aquila, Italy
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