1
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Suladze S, Sarkar R, Rodina N, Bokvist K, Krewinkel M, Scheps D, Nagel N, Bardiaux B, Reif B. Atomic resolution structure of full-length human insulin fibrils. Proc Natl Acad Sci U S A 2024; 121:e2401458121. [PMID: 38809711 PMCID: PMC11161806 DOI: 10.1073/pnas.2401458121] [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: 02/07/2024] [Accepted: 05/02/2024] [Indexed: 05/31/2024] Open
Abstract
Patients with type 1 diabetes mellitus who are dependent on an external supply of insulin develop insulin-derived amyloidosis at the sites of insulin injection. A major component of these plaques is identified as full-length insulin consisting of the two chains A and B. While there have been several reports that characterize insulin misfolding and the biophysical properties of the fibrils, atomic-level information on the insulin fibril architecture remains elusive. We present here an atomic resolution structure of a monomorphic insulin amyloid fibril that has been determined using magic angle spinning solid-state NMR spectroscopy. The structure of the insulin monomer yields a U-shaped fold in which the two chains A and B are arranged in parallel to each other and are oriented perpendicular to the fibril axis. Each chain contains two β-strands. We identify two hydrophobic clusters that together with the three preserved disulfide bridges define the amyloid core structure. The surface of the monomeric amyloid unit cell is hydrophobic implicating a potential dimerization and oligomerization interface for the assembly of several protofilaments in the mature fibril. The structure provides a starting point for the development of drugs that bind to the fibril surface and disrupt secondary nucleation as well as for other therapeutic approaches to attenuate insulin aggregation.
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Affiliation(s)
- Saba Suladze
- Bavarian Nuclear Magnetic Resonance Center at the Department of Biosciences, School of Natural Sciences, Technische Universität München, Garching85747, Germany
- Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Institute of Structural Biology, Neuherberg85764, Germany
| | - Riddhiman Sarkar
- Bavarian Nuclear Magnetic Resonance Center at the Department of Biosciences, School of Natural Sciences, Technische Universität München, Garching85747, Germany
- Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Institute of Structural Biology, Neuherberg85764, Germany
| | - Natalia Rodina
- Bavarian Nuclear Magnetic Resonance Center at the Department of Biosciences, School of Natural Sciences, Technische Universität München, Garching85747, Germany
| | - Krister Bokvist
- Sanofi-Aventis Deutschland GmbH, Diabetes Research, Industriepark Höchst, Frankfurt65926, Germany
| | - Manuel Krewinkel
- Sanofi-Aventis Deutschland GmbH, Manufacturing Science and Technology, Industriepark Höchst, Frankfurt65926, Germany
| | - Daniel Scheps
- Chemistry Manufacturing & Controls Microbial Platform, Sanofi-Aventis Deutschland GmbH, Microbial Platform, Industriepark Höchst, Frankfurt65926, Germany
| | - Norbert Nagel
- Sanofi-Aventis Deutschland GmbH, Tides Platform, Industriepark Höchst, Frankfurt65926, Germany
| | - Benjamin Bardiaux
- Institut Pasteur, Department of Structural Biology and Chemistry, Structural Bioinformatics Unit, CNRS UMR 3528, Université Paris Cité, Paris75015, France
- Institut Pasteur, Department of Structural Biology and Chemistry, Bacterial Transmembrane Systems Unit, CNRS UMR 3528, Université Paris Cité, Paris75015, France
| | - Bernd Reif
- Bavarian Nuclear Magnetic Resonance Center at the Department of Biosciences, School of Natural Sciences, Technische Universität München, Garching85747, Germany
- Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Institute of Structural Biology, Neuherberg85764, Germany
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2
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Dolui S, Roy A, Pal U, Kundu S, Pandit E, N Ratha B, Pariary R, Saha A, Bhunia A, Maiti NC. Raman Spectroscopic Insights of Phase-Separated Insulin Aggregates. ACS PHYSICAL CHEMISTRY AU 2024; 4:268-280. [PMID: 38800728 PMCID: PMC11117687 DOI: 10.1021/acsphyschemau.3c00065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 05/29/2024]
Abstract
Phase-separated protein accumulation through the formation of several aggregate species is linked to the pathology of several human disorders and diseases. Our current investigation envisaged detailed Raman signature and structural intricacy of bovine insulin in its various forms of aggregates produced in situ at an elevated temperature (60 °C). The amide I band in the Raman spectrum of the protein in its native-like conformation appeared at 1655 cm-1 and indicated the presence of a high content of α-helical structure as prepared freshly in acidic pH. The disorder content (turn and coils) also was predominately present in both the monomeric and oligomeric states and was confirmed by the presence shoulder amide I maker band at ∼1680 cm-1. However, the band shifted to ∼1671 cm-1 upon the transformation of the protein solution into fibrillar aggregates as produced for a longer time of incubation. The protein, however, maintained most of its helical conformation in the oligomeric phase; the low-frequency backbone α-helical conformation signal at ∼935 cm-1 was similar to that of freshly prepared aqueous protein solution enriched in helical conformation. The peak intensity was significantly weak in the fibrillar aggregates, and it appeared as a good Raman signature to follow the phase separation and the aggregation behavior of insulin and similar other proteins. Tyrosine phenoxy moieties in the protein may maintained its H-bond donor-acceptor integrity throughout the course of fibril formation; however, it entered in more hydrophobic environment in its journey of fibril formation. In addition, it was noticed that oligomeric bovine insulin maintained the orientation/conformation of the disulfide bonds. However, in the fibrillar state, the disulfide linkages became more strained and preferred to maintain a single conformation state.
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Affiliation(s)
- Sandip Dolui
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Anupam Roy
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Uttam Pal
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Shubham Kundu
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Esha Pandit
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Bhisma N Ratha
- Department
of Chemical Sciences, Bose Institute, Unified Academic Campus, Salt Lake,
Sector V, Kolkata 700091, India
| | - Ranit Pariary
- Department
of Chemical Sciences, Bose Institute, Unified Academic Campus, Salt Lake,
Sector V, Kolkata 700091, India
| | - Achintya Saha
- Department
of Chemical Technology, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009, India
| | - Anirban Bhunia
- Department
of Chemical Sciences, Bose Institute, Unified Academic Campus, Salt Lake,
Sector V, Kolkata 700091, India
| | - Nakul C. Maiti
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
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3
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Harper M, Nudurupati U, Workman RJ, Lakoba TI, Perez N, Nelson D, Ou Y, Punihaole D. Toward determining amyloid fibril structures using experimental constraints from Raman spectroscopy. J Chem Phys 2023; 159:225101. [PMID: 38078532 PMCID: PMC10720587 DOI: 10.1063/5.0177437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
We present structural models for three different amyloid fibril polymorphs prepared from amylin20-29 (sequence SNNFGAILSS) and amyloid-β25-35 (Aβ25-35) (sequence GSNKGAIIGLM) peptides. These models are based on the amide C=O bond and Ramachandran ψ-dihedral angle data from Raman spectroscopy, which were used as structural constraints to guide molecular dynamics (MD) simulations. The resulting structural models indicate that the basic structural motif of amylin20-29 and Aβ25-35 fibrils is extended β-strands. Our data indicate that amylin20-29 forms both antiparallel and parallel β-sheet fibril polymorphs, while Aβ25-35 forms a parallel β-sheet fibril structure. Overall, our work lays the foundation for using Raman spectroscopy in conjunction with MD simulations to determine detailed molecular-level structural models of amyloid fibrils in a manner that complements gold-standard techniques, such as solid-state nuclear magnetic resonance and cryogenic electron microscopy.
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Affiliation(s)
- Madeline Harper
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA
| | - Uma Nudurupati
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA
| | - Riley J. Workman
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Taras I. Lakoba
- Department of Mathematics and Statistics, University of Vermont, Burlington, Vermont 05405, USA
| | - Nicholas Perez
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA
| | - Delaney Nelson
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA
| | - Yangguang Ou
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA
| | - David Punihaole
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA
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4
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Meraj L, Mehmood N, Majeed MI, Nawaz H, Rashid N, Fatima R, Habiba UE, Tahseen H, Naz M, Asghar M, Ghafoor N, Ahmad H. Characterization of structural changes occurring in insulin at different time intervals at room temperature by surface-enhanced Raman spectroscopy. Photodiagnosis Photodyn Ther 2023; 44:103796. [PMID: 37699467 DOI: 10.1016/j.pdpdt.2023.103796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/23/2023] [Accepted: 09/07/2023] [Indexed: 09/14/2023]
Abstract
BACKGROUND Insulin storage above the temperature recommended by food and drug administration (FDA) causes decrease in its functional efficacy due to degradation and aggregation of its protein based active pharmaceutical ingredient (API) that results poor glycemic control in diabetic patients. The aggregation of protein causes serious neurodegenerative diseases such as type-2 diabetes, Huntington disease, Parkinson's disease, and Alzheimer's disease. Surface-enhanced Raman spectroscopy (SERS) has been employed for the denaturation study of many proteins at the temperature above the recommendations of food and drug administration (FDA) (above 30 °C) which indicates potential of technique for such studies. OBJECTIVE SERS along with multivariate discriminating analysis techniques-based analysis of degradation of liquid pharmaceutical insulin protein after regular intervals of time at room temperature to analyze the structural changes in this protein during the storage of insulin pharmaceutical at room temperature. METHODS Silver nanoparticles (Ag-NPs) prepared by chemical reduction method are used as SERS active substrate for the surface enhancement of the insulin spectral signal. SERS spectral measurements of insulin were collected from eight different samples of insulin in the time range of 7 pm to 7 am first at fridge temperature (5 °C), second after half hour and next six with the time difference of 2 h each time at room temperature. The acquired SERS spectral data was preprocessed and analyzed. SERS structural transformations detection and discrimination potential in insulin was further confirmed by applying multivariate discriminating analysis techniques including principal component analysis (PCA) and Partial least square regression analysis (PLSR). RESULTS SERS significantly detects the structural changes produced in insulin even after 2 h of insulin placement at room temperature. PCA successfully differentiates the insulin spectral data obtained after regular intervals of time according to PC-1 (77 %) explained variance. Application of PLSR model provides quantitative confirmation of SERS efficiency, by providing insulin data regression coefficients plot, efficient prediction of time with calibration data set having 0.77 mean square absolute error of calibration (RMSAEC), validation data set with 0.80 mean square absolute error of prediction (RMSAEP) and 0.98 coefficient of determination (R2) for both calibration and validation data set. CONCLUSION SERS is proved as a highly sensitive and discriminating technique to detect and discriminate insulin structural changes after regular intervals of time at room temperature.
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Affiliation(s)
- Lubna Meraj
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Nasir Mehmood
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Muhammad Irfan Majeed
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan.
| | - Haq Nawaz
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan.
| | - Nosheen Rashid
- Department of Chemistry, University of Education, Faisalabad Campus, Faisalabad 38000, Pakistan
| | - Rida Fatima
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Umm E Habiba
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Hira Tahseen
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Maira Naz
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Maria Asghar
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Nida Ghafoor
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Hafsa Ahmad
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
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5
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Chemical Characteristics of Wood Cell Wall with an Emphasis on Ultrastructure: A Mini-Review. FORESTS 2022. [DOI: 10.3390/f13030439] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Wood is complex in its chemical composition that has an important influence on its chemical behavior and mechanical strength. The complexity is reflected in the ultrastructure of the wood cell wall. In particular, the concentration of main components (cellulose, hemicelluloses and lignin) changes depending on many factors such as the different type or parts of wood, and varies in different cell wall layers. From an ultrastructural standpoint, we describe the current level of knowledge about chemical characteristics of the wood cell walls. The information of distribution of main components in the cell walls of normal wood, reaction wood and water-logged archaeological wood, the cellulose microfibrils orientation, and the interactions between main components were presented based on the use of advanced techniques including transmission electron microscopy, scanning electron microscopy, spectral imaging and nuclear magnetic resonance. In addition, the chemical changes of the wood cell wall during pretreatment are discussed. This mini-review not only provides a better understanding of wood chemistry, but also brings new insights into cell wall recalcitrance.
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6
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Dhayalan B, Chatterjee D, Chen YS, Weiss MA. Structural Lessons From the Mutant Proinsulin Syndrome. Front Endocrinol (Lausanne) 2021; 12:754693. [PMID: 34659132 PMCID: PMC8514764 DOI: 10.3389/fendo.2021.754693] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/13/2021] [Indexed: 12/30/2022] Open
Abstract
Insight into folding mechanisms of proinsulin has been provided by analysis of dominant diabetes-associated mutations in the human insulin gene (INS). Such mutations cause pancreatic β-cell dysfunction due to toxic misfolding of a mutant proinsulin and impairment in trans of wild-type insulin secretion. Anticipated by the "Akita" mouse (a classical model of monogenic diabetes mellitus; DM), this syndrome illustrates the paradigm endoreticulum (ER) stress leading to intracellular proteotoxicity. Diverse clinical mutations directly or indirectly perturb native disulfide pairing leading to protein misfolding and aberrant aggregation. Although most introduce or remove a cysteine (Cys; leading in either case to an unpaired thiol group), non-Cys-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the hormone's evolution has been constrained not only by structure-function relationships, but also by the susceptibility of its single-chain precursor to impaired foldability. An intriguing hypothesis posits that INS overexpression in response to peripheral insulin resistance likewise leads to chronic ER stress and β-cell dysfunction in the natural history of non-syndromic Type 2 DM. Cryptic contributions of conserved residues to folding efficiency, as uncovered by rare genetic variants, define molecular links between biophysical principles and the emerging paradigm of Darwinian medicine: Biosynthesis of proinsulin at the edge of non-foldability provides a key determinant of "diabesity" as a pandemic disease of civilization.
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Affiliation(s)
| | | | | | - Michael A. Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
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7
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Abstract
A rapid-acting insulin lispro and long-acting insulin glargine are commonly used for the treatment of diabetes. Clinical cases have described the formation of injectable amyloidosis with these insulin analogues, but their amyloid core regions of fibrils were unknown. To reveal these regions, we have analysed the hydrolyzates of insulin fibrils and its analogues using high-performance liquid chromatography and mass spectrometry methods and found that insulin and its analogues have almost identical amyloid core regions that intersect with the predicted amyloidogenic regions. The obtained results can be used to create new insulin analogues with a low ability to form fibrils. Abbreviations a.a., amino acid residues; HPLC-MS, high-performance liquid chromatography/mass spectrometry; m/z, mass-to-charge ratio; TEM, transmission electron microscopy.
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Affiliation(s)
- Alexey K Surin
- Institute of Protein Research, Russian Academy of Sciences , Pushchino, Russian Federation.,State Research Center for Applied Microbiology and Biotechnology , Obolensk, Russian Federation.,The Branch of the Institute of Bioorganic Chemistry, Russian Academy of Sciences , Pushchino, Russian Federation
| | - Sergei Yu Grishin
- Institute of Protein Research, Russian Academy of Sciences , Pushchino, Russian Federation
| | - Oxana V Galzitskaya
- Institute of Protein Research, Russian Academy of Sciences , Pushchino, Russian Federation.,Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences , Pushchino, Russian Federation
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8
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Waeytens J, Mathurin J, Deniset-Besseau A, Arluison V, Bousset L, Rezaei H, Raussens V, Dazzi A. Probing amyloid fibril secondary structures by infrared nanospectroscopy: experimental and theoretical considerations. Analyst 2021; 146:132-145. [PMID: 33107501 DOI: 10.1039/d0an01545h] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Amyloid fibrils are composed of aggregated peptides or proteins in a fibrillary structure with a higher β-sheet content than their native structure. Attenuated total reflection Fourier transform infrared spectroscopy only provides bulk analysis of a sample therefore it is impossible to discriminate between different aggregated structures. To overcome this limitation, near-field techniques like AFM-IR have emerged in the last twenty years to allow infrared nanospectroscopy. This technique obtains IR spectra with a spatial resolution of ten nanometres, the size of isolated fibrils. Here, we present essential practical considerations to avoid misinterpretations and artefacts during these analyses. Effects of polarization of the incident IR laser, illumination configuration and coating of the AFM probes are discussed, including the advantages and drawbacks of their use. This approach will improve interpretation of AFM-IR spectra especially for the determination of secondary structures of species not accessible using classical ATR-FTIR.
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Affiliation(s)
- Jehan Waeytens
- Structure et Fonction des Membranes Biologiques, Université libre de Bruxelles, Bruxelles, Belgique.
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9
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Dhayalan B, Chatterjee D, Chen YS, Weiss MA. Diabetes mellitus due to toxic misfolding of proinsulin variants. Mol Metab 2021:101229. [PMID: 33823319 DOI: 10.1016/j.molmet.2021.101229] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/10/2021] [Accepted: 03/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Dominant mutations in the human insulin gene (INS) lead to pancreatic β-cell dysfunction and diabetes mellitus (DM) due to toxic misfolding of a mutant proinsulin. Analogous to a classical mouse model of monogenic DM ("Akita"), this syndrome highlights the susceptibility of β-cells to endoreticulum (ER) stress due to protein misfolding and aberrant aggregation. SCOPE OF REVIEW Diverse clinical mutations directly or indirectly perturb native disulfide pairing. Whereas most introduce or remove a cysteine (Cys; leading in either case to an unpaired thiol group), non-Cys-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the hormone's evolution has been constrained not only by structure-function relationships but also by the susceptibility of its single-chain precursor to impaired foldability. An intriguing hypothesis posits that INS overexpression in response to peripheral insulin resistance likewise leads to chronic ER stress and β-cell dysfunction in the natural history of nonsyndromic Type 2 DM. MAJOR CONCLUSIONS Cryptic contributions of conserved residues to folding efficiency, as uncovered by rare genetic variants, define molecular links between biophysical principles and the emerging paradigm of Darwinian medicine: Biosynthesis of proinsulin at the edge of nonfoldability provides a key determinant of "diabesity" as a pandemic disease of civilization.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Deepak Chatterjee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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10
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Ratha BN, Kar RK, Bednarikova Z, Gazova Z, Kotler SA, Raha S, De S, Maiti NC, Bhunia A. Molecular Details of a Salt Bridge and Its Role in Insulin Fibrillation by NMR and Raman Spectroscopic Analysis. J Phys Chem B 2020; 124:1125-1136. [PMID: 31958230 DOI: 10.1021/acs.jpcb.9b10349] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Insulin, a simple polypeptide hormone with huge biological importance, has long been known to self-assemble in vitro and form amyloid-like fibrillar aggregates. Utilizing high-resolution NMR, Raman spectroscopy, and computational analysis, we demonstrate that the fluctuation of the carboxyl terminal (C-ter) residues of the insulin B-chain plays a key role in the growth phase of insulin aggregation. By comparing the insulin sourced from bovine, human, and the modified glargine (GI), we observed reduced aggregation propensity in the GI variant, resulting from two additional Arg residues at its C-ter. NMR analysis showed atomic contacts and residue-specific interactions, particularly the salt bridge and H-bond formed among the C-ter residues Arg31B, Lys29B, and Glu4A. These inter-residue interactions were reflected in strong nuclear Overhauser effects among Arg31BδH-Glu4AδH and Lys29BδHs-Glu4AδH in GI, as well as the associated downfield chemical shift of several A-chain amino terminal (N-ter) residues. The two additional Arg residues of GI, Arg31B and Arg32B, enhanced the stability of the GI native structure by strengthening the Arg31B, Lys29B, and Glu4A salt bridge, thus reducing extensive thermal distortion and fluctuation of the terminal residues. The high stability of the salt bridge retards tertiary collapse, a crucial biochemical event for oligomerization and subsequent fibril formation. Circular dichroism and Raman spectroscopic measurement also suggest slow structural distortion in the early phase of the aggregation of GI because of the restricted mobility of the C-ter residues as explained by NMR. In addition, the structural and dynamic parameters derived from molecular dynamics simulations of insulin variants highlight the role of residue-specific contacts in aggregation and amyloid-like fibril formation.
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Affiliation(s)
- Bhisma N Ratha
- Department of Biophysics , Bose Institute , P-1/12 CIT Scheme VII (M) , Kolkata 700054 , India
| | - Rajiv K Kar
- Department of Biophysics , Bose Institute , P-1/12 CIT Scheme VII (M) , Kolkata 700054 , India
| | - Zuzana Bednarikova
- Department of Biophysics , Institute of Experimental Physics Slovak Academy of Sciences , Kosice 040 01 , Slovakia
| | - Zuzana Gazova
- Department of Biophysics , Institute of Experimental Physics Slovak Academy of Sciences , Kosice 040 01 , Slovakia
| | - Samuel A Kotler
- National Center for Advancing Translational Sciences , National Institutes of Health , Rockville , Maryland 20850 , United States
| | - Sreyan Raha
- Department of Physics , Bose Institute , 93/1 APC Road , Kolkata 700009 , India
| | - Soumya De
- School of Bioscience , IIT Kharagpur , Kharagpur 721302 , India
| | - Nakul C Maiti
- Division Structural Biology and Bioinformatics , CSIR-Indian Institute of Chemical Biology , Kolkata 700032 , India
| | - Anirban Bhunia
- Department of Biophysics , Bose Institute , P-1/12 CIT Scheme VII (M) , Kolkata 700054 , India
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11
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Akbarian M, Rezaie E, Farjadian F, Bazyar Z, Hosseini-Sarvari M, Ara EM, Mirhosseini SA, Amani J. Inhibitory effect of coumarin and its analogs on insulin fibrillation /cytotoxicity is depend on oligomerization states of the protein. RSC Adv 2020; 10:38260-38274. [PMID: 35517555 PMCID: PMC9057281 DOI: 10.1039/d0ra07710k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/11/2020] [Indexed: 12/02/2022] Open
Abstract
Looking through a historical lens, attention to the stabilization of pharmaceutical proteins/peptides has been dramatically increased. Human insulin is the most challenging and the most widely used pharmaceutical protein in the world. In this study, the protein and coumarin as a plant-derived phenolic compound and two coumarin analogs with different moieties were investigated to evaluate the protein fibrillation and cytotoxicity. The obtained data showed that with a change in environmental pH, the behavior of the compounds on the process of insulin fibrillation will be changed completely. Coumarin (C1) and its hydrophobic analog, 7-methyl coumarin (C2), in an acidic environment, inhibit insulin fibrillation, change the oligomerization state of insulin and produce fibrils with notable lateral interactions with low cytotoxicity. However, negatively-charged 3-trifluoromethyl coumarin (C3) without significant changes in insulin structure and by altering the oligomerization state of the protein, slightly accelerates hormone fibrillation. Also, the compounds showed a disulfide protecting role during protein aggregation. Regarding the toxicity of the fibrils, it was observed that in addition to the secondary structures of proteinous fibrils, the ability to destroy the cell membrane is also related to the length of the fibrils and their degree of lateral interactions. By and large, this work can be useful in finding a better formulation for bio-pharmaceutical macro-molecules. The effect of the applied compounds on insulin fibrillation at two pHs. By and large, the compounds through changing the oligomerization states and altering structure integrity of insulin can govern the fibrillation process.![]()
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Affiliation(s)
- Mohsen Akbarian
- Molecular Biology Research Center
- Systems Biology and Poisonings Institute
- Baqiyatallah University of Medical Sciences
- Tehran
- Iran
| | - Ehsan Rezaie
- Molecular Biology Research Center
- Systems Biology and Poisonings Institute
- Baqiyatallah University of Medical Sciences
- Tehran
- Iran
| | - Fatemeh Farjadian
- Pharmaceutical Sciences Research Center
- Shiraz University of Medical Sciences
- Shiraz
- Iran
| | - Zahra Bazyar
- Department of Chemistry
- Shiraz University
- Shiraz
- Iran
| | | | - Ehsan Malek Ara
- Applied Microbiology Research Center
- Baqiyatallah University of Medical Sciences
- Tehran
- Iran
| | - Seyed Ali Mirhosseini
- Applied Microbiology Research Center
- Baqiyatallah University of Medical Sciences
- Tehran
- Iran
| | - Jafar Amani
- Applied Microbiology Research Center
- Baqiyatallah University of Medical Sciences
- Tehran
- Iran
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12
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Khatun S, Singh A, Pawar N, Gupta AN. Aggregation of amylin: Spectroscopic investigation. Int J Biol Macromol 2019; 133:1242-1248. [PMID: 31028814 DOI: 10.1016/j.ijbiomac.2019.04.167] [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: 02/26/2019] [Revised: 04/12/2019] [Accepted: 04/23/2019] [Indexed: 12/17/2022]
Abstract
Apart from its relevance to pathology, protein misfolding disease like Type-II Diabetes Mellitus, caused by amyloids of amylin protein has attracted more attention due to structural changes occurring during the aggregation process. We report extensive spectroscopy data of amylin during fibril formation through Raman, FTIR, CD, UV-vis absorption and photoluminescence (PL) spectroscopy. UV-vis and PL spectrum showed the sigmoidal growth of fibril with a lag time of ~2 days, which is consistent with earlier reported work using dynamic light scattering (DLS). Raman spectra revealed the formation of parallel and anti-parallel β-sheet from 0% to 20% with ageing (1st day to 21st day) at pH 6.5 ± 0.1. The results are corroborated by CD and FTIR data. These show the change in β-sheet by 23% at pH 6.5 ± 0.1, 26% at pH = 1.0 ± 0.1 and 30% at pH = 12 ± 0.1. It is also shown that the formation and conversion of other secondary structures into β-sheet is very sensitive towards the pH and ageing. The study may be used for the development of therapeutic strategies that could inhibit or even reverse the process of aggregation.
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Affiliation(s)
- Suparna Khatun
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India
| | - Anurag Singh
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India
| | - Nisha Pawar
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India
| | - Amar Nath Gupta
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India.
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Ratha BN, Kar RK, Kalita S, Kalita S, Raha S, Singha A, Garai K, Mandal B, Bhunia A. Sequence specificity of amylin-insulin interaction: a fragment-based insulin fibrillation inhibition study. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:405-415. [DOI: 10.1016/j.bbapap.2019.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/03/2019] [Accepted: 01/13/2019] [Indexed: 01/10/2023]
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14
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Devitt G, Howard K, Mudher A, Mahajan S. Raman Spectroscopy: An Emerging Tool in Neurodegenerative Disease Research and Diagnosis. ACS Chem Neurosci 2018; 9:404-420. [PMID: 29308873 DOI: 10.1021/acschemneuro.7b00413] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The pathogenesis underlining many neurodegenerative diseases remains incompletely understood. The lack of effective biomarkers and disease preventative medicine demands the development of new techniques to efficiently probe the mechanisms of disease and to detect early biomarkers predictive of disease onset. Raman spectroscopy is an established technique that allows the label-free fingerprinting and imaging of molecules based on their chemical constitution and structure. While analysis of isolated biological molecules has been widespread in the chemical community, applications of Raman spectroscopy to study clinically relevant biological species, disease pathogenesis, and diagnosis have been rapidly increasing since the past decade. The growing number of biomedical applications has shown the potential of Raman spectroscopy for detection of novel biomarkers that could enable the rapid and accurate screening of disease susceptibility and onset. Here we provide an overview of Raman spectroscopy and related techniques and their application to neurodegenerative diseases. We further discuss their potential utility in research, biomarker detection, and diagnosis. Challenges to routine use of Raman spectroscopy in the context of neuroscience research are also presented.
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15
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Dolui S, Roy A, Pal U, Saha A, Maiti NC. Structural Insight of Amyloidogenic Intermediates of Human Insulin. ACS OMEGA 2018; 3:2452-2462. [PMID: 30023834 PMCID: PMC6045404 DOI: 10.1021/acsomega.7b01776] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 02/16/2018] [Indexed: 05/27/2023]
Abstract
Engaging Raman spectroscopy as a primary tool, we investigated the early events of insulin fibrilization and determined the structural content present in oligomer and protofibrils that are formed as intermediates in the fibril formation pathway. Insulin oligomer, as obtained upon incubation of zinc-free insulin at 60 °C, was mostly spherical in shape, with a diameter of 3-5 nm. Longer incubation produced "necklace"-like beaded protofibrillar assembly species. These intermediates eventually transformed into 5-8 nm thick fibers with smooth surface texture. A broad amide I band in the Raman spectrum of insulin monomer appeared at 1659 cm-1, with a shoulder band at 1676 cm-1. This signature suggested the presence of major helical and extended secondary structure of the protein backbone. In the oligomeric state, the protein maintained its helical imprint (∼50%) and no substantial increment of the compact cross-β-sheet structure was observed. A nonamide helix signature band at 940 cm-1 was present in the oligomeric state, and it was weakened in the fibrillar structure. The 1-anilino-8-naphthalene-sulfonate binding study strongly suggested that a collapse in the tertiary structure, not the major secondary structural realignment, was the dominant factor in the formation of oligomers. In the fibrillar state, the contents of helical and disordered secondary structures decreased significantly and the β-sheet amount increased to ∼62%. The narrow amide I Raman band at 1674 cm-1 in the fibrillar state connoted the formation of vibrationally restricted highly organized β-sheet structure with quaternary realignment into steric-zipped species.
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Affiliation(s)
- Sandip Dolui
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Anupam Roy
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
| | - Uttam Pal
- Chemical
Sciences Division, Saha Institute of Nuclear
Physics, 1/AF Bidhannagar, Kolkata 700064, India
| | - Achintya Saha
- Department
of Chemical Technology, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009, India
| | - Nakul C. Maiti
- Structural
Biology and Bioinformatics Division, Indian
Institute of Chemical Biology, Council of Scientific and Industrial
Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India
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16
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Tracking the amyloidogenic core of IAPP amyloid fibrils: Insights from micro-Raman spectroscopy. J Struct Biol 2017; 199:140-152. [PMID: 28602716 DOI: 10.1016/j.jsb.2017.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 05/19/2017] [Accepted: 06/03/2017] [Indexed: 12/14/2022]
Abstract
Human islet amyloid polypeptide (hIAPP) is the major protein component of extracellular amyloid deposits, located in the islets of Langerhans, a hallmark of type II diabetes. The underlying mechanisms of IAPP aggregation have not yet been clearly defined, although the highly amyloidogenic sequence of the protein has been extensively studied. Several segments have been highlighted as aggregation-prone regions (APRs), with much attention focused on the central 8-17 and 20-29 stretches. In this work, we employ micro-Raman spectroscopy to identify specific regions that are contributing to or are excluded from the amyloidogenic core of IAPP amyloid fibrils. Our results demonstrate that both the N-terminal region containing a conserved disulfide bond between Cys residues at positions 2 and 7, and the C-terminal region containing the only Tyr residue are excluded from the amyloid core. Finally, by performing detailed aggregation assays and molecular dynamics simulations on a number of IAPP variants, we demonstrate that point mutations within the central APRs contribute to the reduction of the overall amyloidogenic potential of the protein but do not completely abolish the formation of IAPP amyloid fibrils.
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17
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Zhang G, Li J, Cui P, Wang T, Jiang J, Prezhdo OV. Two-Dimensional Linear Dichroism Spectroscopy for Identifying Protein Orientation and Secondary Structure Composition. J Phys Chem Lett 2017; 8:1031-1037. [PMID: 28198629 DOI: 10.1021/acs.jpclett.7b00311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Quantitative measurements of protein orientation and secondary structure composition are of great importance for protein biotechnology applications and disease treatments, and yet, they are technically challenging for a spectroscopic study. On the basis of quantum mechanics/molecular mechanics simulations, we demonstrate that two-dimensional (2D) linear dichroism spectroscopy is capable of probing the direction of α-helix motifs in proteins. Compared to the conventional linear dichroism (LD) spectra, 2D spectra double the measurable range of orientation of secondary structures. In addition, by calculating the ratio of transverse ππ* signals to longitudinal ππ* signals in 2D spectra, we can achieve quantitative measurement of the fraction of α-helix content in a protein.
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Affiliation(s)
- Guozhen Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Jun Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Peng Cui
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Tao Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Jun Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Oleg V Prezhdo
- Department of Chemistry, Department of Physics, and Department of Astronomy, University of Southern California , Los Angeles, California 90089, United States
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Cannon D, Eichhorn S, Donald AM. Structure of Spherulites in Insulin, β-Lactoglobulin, and Amyloid β. ACS OMEGA 2016; 1:915-922. [PMID: 31457172 PMCID: PMC6640738 DOI: 10.1021/acsomega.6b00208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/27/2016] [Indexed: 05/12/2023]
Abstract
Under denaturing conditions such as low pH and elevated temperatures, proteins in vitro can misfold and aggregate to form long rigid rods called amyloid fibrils; further self-assembly can lead to larger structures termed spherulites. Both of these aggregates resemble amyloid tangles and plaques associated with Alzheimer's disease in vivo. The ability to form such aggregates in a multitude of different proteins suggests that it is a generic ability in their mechanism to form. Little is known about the structure of these large spherulites ranging from 5 to 100 microns and whether they can reproducibly form in amyloid β (1-40) (Aβ40), a 40-amino acid residue peptide, which is one of the major components of Alzheimer's amyloid deposits. Here, we show that spherulites can readily form in Aβ40 under certain monomerization and denaturing conditions. Using polarized and nonpolarized Raman spectroscopy, we analyzed the secondary structure of spherulites formed from three different proteins: insulin, β-lactoglobulin (BLG), and Aβ40. Visually, these spherulites have a characteristic "Maltese Cross" structure under crossed polarizers through an optical microscope. However, our results indicate that insulin and Aβ40 spherulites have similar core structures consisting mostly of random coils with radiating fibrils, whereas BLG mostly contains β-sheets and fibrils that are likely to be spiraling from the core to the edge.
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Affiliation(s)
- Danielle Cannon
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, U.K.
| | - Stephen
J. Eichhorn
- School
of Materials, University of Manchester, Sackville Street, M13 9PL Manchester, U.K.
| | - Athene M. Donald
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, U.K.
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Sereda V, Ralbovsky NM, Vasudev MC, Naik RR, Lednev IK. Polarized Raman Spectroscopy for Determining the Orientation of di-D-phenylalanine Molecules in a Nanotube. JOURNAL OF RAMAN SPECTROSCOPY : JRS 2016; 47:1056-1062. [PMID: 27795612 PMCID: PMC5079532 DOI: 10.1002/jrs.4884] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Self-assembly of short peptides into nanostructures has become an important strategy for the bottom-up fabrication of nanomaterials. Significant interest to such peptide-based building blocks is due to the opportunity to control the structure and properties of well-structured nanotubes, nanofibrils, and hydrogels. X-ray crystallography and solution NMR, two major tools of structural biology, have significant limitations when applied to peptide nanotubes because of their non-crystalline structure and large weight. Polarized Raman spectroscopy was utilized for structural characterization of well-aligned D-Diphenylalanine nanotubes. The orientation of selected chemical groups relative to the main axis of the nanotube was determined. Specifically, the C-N bond of CNH3+groups is oriented parallel to the nanotube axis, the peptides' carbonyl groups are tilted at approximately 54° from the axis and the COO- groups run perpendicular to the axis. The determined orientation of chemical groups allowed the understanding of the orientation of D-diphenylalanine molecule that is consistent with its equilibrium conformation. The obtained data indicate that there is only one orientation of D-diphenylalanine molecules with respect to the nanotube main axis.
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Affiliation(s)
- Valentin Sereda
- Department of Chemistry, University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, United States
| | - Nicole M. Ralbovsky
- Department of Chemistry, University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, United States
| | - Milana C. Vasudev
- Department of Bioengineering, University of Massachusetts Dartmouth, 285 Old Westport Road, Dartmouth MA 02747, United States
| | - Rajesh R. Naik
- Soft Matter Materials Branch, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Igor K. Lednev
- Department of Chemistry, University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, United States
- Corresponding author: , Phone: (518) 591 8863, Fax: (518) 442-3462
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20
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Ivancic VA, Ekanayake O, Lazo ND. Binding Modes of Thioflavin T on the Surface of Amyloid Fibrils Studied by NMR. Chemphyschem 2016; 17:2461-4. [DOI: 10.1002/cphc.201600246] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/06/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Valerie A. Ivancic
- Carlson School of Chemistry and Biochemistry; Clark University; 950 Main St Worcester MA 01610 USA
| | - Oshini Ekanayake
- Department of Chemistry and Biochemistry; University of Delaware; Newark Delaware 19716 USA
| | - Noel D. Lazo
- Carlson School of Chemistry and Biochemistry; Clark University; 950 Main St Worcester MA 01610 USA
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21
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Xia H, Wang R, Liu Y, Cheng J, Zou G, Zhang Q, Zhang D, Wang P, Ming H, Badugu R, Lakowicz JR. Active Polymer Microfiber with Controlled Polarization Sensitivity. ADVANCED OPTICAL MATERIALS 2016; 4:371-377. [PMID: 27099828 PMCID: PMC4835039 DOI: 10.1002/adom.201500552] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Controlled Polarization Sensitivity of an active polymer microfiber has been proposed and realized with the electrospun method. The fluorescence intensity guiding through this active polymer microfiber shows high sensitivity to the polarization state of the excitation light. What is more, the fluorescence out-coupled from tip of the microfiber can be of designed polarization state. Principle of these phenomena lies on the ordered and controlled orientation of the polydiacetylene (PDA) main chains inside polymer microfiber.
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Affiliation(s)
- Hongyan Xia
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, iChEM, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Ruxue Wang
- Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Yingying Liu
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, iChEM, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Junjie Cheng
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, iChEM, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Gang Zou
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, iChEM, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Qijin Zhang
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, iChEM, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Douguo Zhang
- Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Pei Wang
- Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Hai Ming
- Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Ramachandram Badugu
- Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Joseph R. Lakowicz
- Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
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