1
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Mignon J, Leyder T, Mottet D, Uversky VN, Michaux C. In-depth investigation of the effect of pH on the autofluorescence properties of DPF3b and DPF3a amyloid fibrils. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 313:124156. [PMID: 38508075 DOI: 10.1016/j.saa.2024.124156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/10/2024] [Accepted: 03/12/2024] [Indexed: 03/22/2024]
Abstract
Double PHD fingers 3 (DPF3) protein exists as two splicing variants, DPF3b and DPF3a, the involvement of which in human cancer and neurodegeneration is beginning to be increasingly recognised. Both isoforms have recently been identified as intrinsically disordered proteins able to undergo amyloid fibrillation. Upon their aggregation, DPF3 proteins exhibit an intrinsic fluorescence in the visible range, referred to as deep-blue autofluorescence (dbAF). Comprehension of such phenomenon remaining elusive, we investigated in the present study the influence of pH on the optical properties of DPF3b and DPF3a fibrils. By varying the excitation wavelength and the pH condition, the two isoforms were revealed to display several autofluorescence modes that were defined as violet, deep-blue, and blue-green according to their emission range. Complementarily, analysis of excitation spectra and red edge shift plots allowed to better decipher their photoselection mechanism and to highlight isoform-specific excitation-emission features. Furthermore, the observed violation to Kasha-Vavilov's rule was attributed to red edge excitation shift effects, which were impacted by pH-mediated H-bond disruption, leading to changes in intramolecular charge and proton transfer, or π-electrons delocalisation. Finally, emergence of different autofluorescence emitters was likely related to structurally distinct fibrillar assemblies between isoforms, as well as to discrepancies in the amino acid composition of their aggregation prone regions.
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Affiliation(s)
- Julien Mignon
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Institute of Structured Matter (NISM), University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Research Institute for Life Sciences (NARILIS), University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
| | - Tanguy Leyder
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
| | - Denis Mottet
- Gene Expression and Cancer Laboratory, GIGA-Molecular Biology of Diseases, University of Liège, B34, Avenue de l'Hôpital, 4000 Liège, Belgium.
| | - Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States.
| | - Catherine Michaux
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Institute of Structured Matter (NISM), University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Research Institute for Life Sciences (NARILIS), University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
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2
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Balasco N, Diaferia C, Rosa E, Monti A, Ruvo M, Doti N, Vitagliano L. A Comprehensive Analysis of the Intrinsic Visible Fluorescence Emitted by Peptide/Protein Amyloid-like Assemblies. Int J Mol Sci 2023; 24:ijms24098372. [PMID: 37176084 PMCID: PMC10178990 DOI: 10.3390/ijms24098372] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
Amyloid aggregation is a widespread process that involves proteins and peptides with different molecular complexity and amino acid composition. The structural motif (cross-β) underlying this supramolecular organization generates aggregates endowed with special mechanical and spectroscopic properties with huge implications in biomedical and technological fields, including emerging precision medicine. The puzzling ability of these assemblies to emit intrinsic and label-free fluorescence in regions of the electromagnetic spectrum, such as visible and even infrared, usually considered to be forbidden in the polypeptide chain, has attracted interest for its many implications in both basic and applied science. Despite the interest in this phenomenon, the physical basis of its origin is still poorly understood. To gain a global view of the available information on this phenomenon, we here provide an exhaustive survey of the current literature in which original data on this fluorescence have been reported. The emitting systems have been classified in terms of their molecular complexity, amino acid composition, and physical state. Information about the wavelength of the radiation used for the excitation as well as the emission range/peak has also been retrieved. The data collected here provide a picture of the complexity of this multifaceted phenomenon that could be helpful for future studies aimed at defining its structural and electronic basis and/or stimulating new applications.
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Affiliation(s)
- Nicole Balasco
- Institute of Molecular Biology and Pathology, National Research Council (CNR), Department of Chemistry, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Carlo Diaferia
- Department of Pharmacy and CIRPeB, Research Centre on Bioactive Peptides "Carlo Pedone", University of Naples "Federico II", Via Montesano 49, 80131 Naples, Italy
| | - Elisabetta Rosa
- Department of Pharmacy and CIRPeB, Research Centre on Bioactive Peptides "Carlo Pedone", University of Naples "Federico II", Via Montesano 49, 80131 Naples, Italy
| | - Alessandra Monti
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
| | - Menotti Ruvo
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
| | - Nunzianna Doti
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
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3
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Sapra R, Gupta M, Khare K, Chowdhury PK, Haridas V. Fluorescence by self-assembly: autofluorescent peptide vesicles and fibers. Analyst 2023; 148:973-984. [PMID: 36756978 DOI: 10.1039/d3an00124e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A series of oxidized cysteinyl peptides ([P-Cys-X-OMe]2; P = Boc or H; X = Trp or Glu) showed vesicular and fibrillar assemblies. The anatomy of the self-assembled vesicles from the water-soluble cystine peptide [Cys-Trp-OMe]2 (1a) has been investigated by using various fluorescent probes such as ammonium 8-anilinonaphthalene-1-sulfonate, Nile Red and pyrene. The morphological characterization was carried out by fluorescence lifetime imaging microscopy (FLIM) and super resolution-structured illumination microscopy (SR-SIM) utilizing the autofluorescence of the vesicles stemming from the self-assembly. The self-assembled structures are also observed in solution as evident from the quantitative phase images obtained using a dual-mode digital holographic microscope (DHM) system. Present investigations show that the self-assembly is enthalpy- and entropy-driven in the aqueous medium. Based on the CD spectral studies, we proposed that 1a organizes into vesicles through the sequestration of indole units. We observed that the solutions of dipeptides 1a-b exhibit autofluorescence in the blue region upon excitation at a wavelength >350 nm. Detailed spectroscopic studies on the peptides lacking tryptophan 2a-b unequivocally showed that the autofluorescence stems exclusively from peptide aggregation. Our experimental results with appropriate controls revealed that the clustering of carbonyl chromophores is central to autofluorescence. Autofluorescence was also used to probe the vesicle formation without using any external fluorescent probe. To the best of our knowledge, this is the first report on autofluorescent vesicles formed by the spontaneous association of dipeptides. We also found that the vesicles formed by 1a can act as a host for guests like C60. The biocompatibility and biodegradability of these peptides along with the autofluorescent nature and guest binding ability of peptide-based vesicles offer numerous applications in the biomedical area.
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Affiliation(s)
- Rachit Sapra
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Monika Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Kedar Khare
- Optics and Photonics Centre, Indian Institute of Technology Delhi, New Delhi-110016, India
| | - Pramit K Chowdhury
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - V Haridas
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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4
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Jesus CSH, Soares HT, Piedade AP, Cortes L, Serpa C. Using amyloid autofluorescence as a biomarker for lysozyme aggregation inhibition. Analyst 2021; 146:2383-2391. [PMID: 33646214 DOI: 10.1039/d0an02260h] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The assembly of proteins into amyloidogenic aggregates underlies the onset and symptoms of several pathologies, including Alzheimer's disease, Parkinson's disease and type II diabetes. Among the efforts for fighting these diseases, there is a great demand for developing novel, fast and reliable methods for in vitro screening of new drugs that may suppress or reverse amyloidogenesis. Recent studies unravelled a progressive increase in a blue autofluorescence upon amyloid formation originated from many different proteins, including the peptide amyloid-β, lysozyme or insulin. Herein, we propose a drug screening method using this property, avoiding the use of external probe dyes. We demonstrate that the inhibition of lysozyme amyloid formation by means of two known inhibitors, tartrazine and amaranth, can be monitored based on the autofluorescence of lysozyme amyloid aggregates. Our results show that amyloid luminescence is an intrinsic property that can be potentially applied in a screening assay, allowing the ranking of drug efficiency. The assays demonstrated here are fast to perform and suitable for scaling using microplate assays, configuring a new sensitive and economically feasible method.
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Affiliation(s)
- Catarina S H Jesus
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
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5
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Ahanger I, Parray ZA, Nasreen K, Ahmad F, Hassan MI, Islam A, Sharma A. Heparin Accelerates the Protein Aggregation via the Downhill Polymerization Mechanism: Multi-Spectroscopic Studies to Delineate the Implications on Proteinopathies. ACS OMEGA 2021; 6:2328-2339. [PMID: 33521471 PMCID: PMC7841943 DOI: 10.1021/acsomega.0c05638] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
Heparin is one of the members of the glycosaminoglycan (GAG) family, which has been associated with protein aggregation diseases including Alzheimer's disease, Parkinson's disease, and prion diseases. Here, we investigate heparin-induced aggregation of bovine serum albumin (BSA) using different spectroscopic techniques [absorption, 8-anilino-1-naphthalene sulfonic acid (ANS) and thioflavin T (ThT) fluorescence binding, and far- and near-UV circular dichroism]. Kinetic measurements revealed that heparin is involved in the significant enhancement of aggregation of BSA. The outcomes showed dearth of the lag phase and a considerable change in rate constant, which provides conclusive evidence, that is, heparin-induced BSA aggregation involves the pathway of the downhill polymerization mechanism. Heparin also causes enhancement of fluorescence intensity of BSA significantly. Moreover, heparin was observed to form amyloids and amorphous aggregates of BSA which were confirmed by ThT and ANS fluorescence, respectively. Circular dichroism measurements exhibit a considerable change in the secondary and tertiary structure of the protein due to heparin. In addition, binding studies of heparin with BSA to know the cause of aggregation, isothermal titration calorimetry measurements were exploited, from which heparin was observed to promote the aggregation of BSA by virtue of electrostatic interactions between positively charged amino acid residues of protein and negatively charged groups of GAG. The nature of binding of heparin with BSA is very much apparent with an appreciable heat of interaction and is largely exothermic in nature. Moreover, the Gibbs free energy change (ΔG) is negative, which indicates spontaneous nature of binding, and the enthalpy change (ΔH) and entropy change (ΔS) are also largely negative, which suggest that the interaction is driven by hydrogen bonding.
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Affiliation(s)
- Ishfaq
Ahmad Ahanger
- Department
of Chemistry, Biochemistry and Forensic Science, Amity School of Applied
Sciences, Amity University Haryana, Gurugram 122 413, India
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Zahoor Ahmad Parray
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Khalida Nasreen
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Faizan Ahmad
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Md. Imtaiyaz Hassan
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Asimul Islam
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Anurag Sharma
- Department
of Chemistry, Biochemistry and Forensic Science, Amity School of Applied
Sciences, Amity University Haryana, Gurugram 122 413, India
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6
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Abdelrahman S, Alghrably M, Lachowicz JI, Emwas AH, Hauser CAE, Jaremko M. "What Doesn't Kill You Makes You Stronger": Future Applications of Amyloid Aggregates in Biomedicine. Molecules 2020; 25:E5245. [PMID: 33187056 PMCID: PMC7696280 DOI: 10.3390/molecules25225245] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/24/2020] [Accepted: 10/27/2020] [Indexed: 02/06/2023] Open
Abstract
Amyloid proteins are linked to the pathogenesis of several diseases including Alzheimer's disease, but at the same time a range of functional amyloids are physiologically important in humans. Although the disease pathogenies have been associated with protein aggregation, the mechanisms and factors that lead to protein aggregation are not completely understood. Paradoxically, unique characteristics of amyloids provide new opportunities for engineering innovative materials with biomedical applications. In this review, we discuss not only outstanding advances in biomedical applications of amyloid peptides, but also the mechanism of amyloid aggregation, factors affecting the process, and core sequences driving the aggregation. We aim with this review to provide a useful manual for those who engineer amyloids for innovative medicine solutions.
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Affiliation(s)
- Sherin Abdelrahman
- Laboratory for Nanomedicine, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia;
| | - Mawadda Alghrably
- Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia;
| | - Joanna Izabela Lachowicz
- Department of Medical Sciences and Public Health, University of Cagliari, Policlinico Universitario, I-09042 Monserrato, Italy
| | - Abdul-Hamid Emwas
- Core Labs, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia;
| | - Charlotte A. E. Hauser
- Laboratory for Nanomedicine, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia;
| | - Mariusz Jaremko
- Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia;
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7
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Wang Y, Zhao Z, Yuan WZ. Intrinsic Luminescence from Nonaromatic Biomolecules. Chempluschem 2020; 85:1065-1080. [DOI: 10.1002/cplu.202000021] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 05/02/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Yunzhong Wang
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesShanghai Key Lab of Electrical Insulation and Thermal AgingShanghai Electrochemical Energy Devices Research CenterShanghai Jiao Tong University No. 800 Dongchuan Rd. Minhang District Shanghai 200240 P. R. China
| | - Zihao Zhao
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesShanghai Key Lab of Electrical Insulation and Thermal AgingShanghai Electrochemical Energy Devices Research CenterShanghai Jiao Tong University No. 800 Dongchuan Rd. Minhang District Shanghai 200240 P. R. China
| | - Wang Zhang Yuan
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesShanghai Key Lab of Electrical Insulation and Thermal AgingShanghai Electrochemical Energy Devices Research CenterShanghai Jiao Tong University No. 800 Dongchuan Rd. Minhang District Shanghai 200240 P. R. China
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8
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Ziaunys M, Sneideris T, Smirnovas V. Exploring the potential of deep-blue autofluorescence for monitoring amyloid fibril formation and dissociation. PeerJ 2019; 7:e7554. [PMID: 31440437 PMCID: PMC6699583 DOI: 10.7717/peerj.7554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 07/25/2019] [Indexed: 02/03/2023] Open
Abstract
Protein aggregation into amyloid fibrils has been linked to multiple neurodegenerative disorders. Determining the kinetics of fibril formation, as well as their structural stability are important for the mechanistic understanding of amyloid aggregation. Tracking both fibril association and dissociation is usually performed by measuring light scattering of the solution or fluorescence of amyloid specific dyes, such as thioflavin-T. A possible addition to these methods is the recently discovered deep-blue autofluorescence (dbAF), which is linked to amyloid formation. In this work we explore the potential of this phenomenon to monitor amyloid fibril formation and dissociation, as well as show its possible relation to fibril size rather than amyloid structure.
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Affiliation(s)
- Mantas Ziaunys
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
| | - Tomas Sneideris
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
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9
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Dissection of the deep-blue autofluorescence changes accompanying amyloid fibrillation. Arch Biochem Biophys 2018; 651:13-20. [PMID: 29803394 DOI: 10.1016/j.abb.2018.05.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/02/2018] [Accepted: 05/23/2018] [Indexed: 11/21/2022]
Abstract
Pathogenesis of numerous diseases is associated with the formation of amyloid fibrils. Extrinsic fluorescent dyes, including Thioflavin T (ThT), are used to follow the fibrillation kinetics. It has recently been reported that the so-called deep-blue autofluorescence (dbAF) is changing during the aggregation process. However, the origin of dbAF and the reasons for its change remain debatable. Here, the kinetics of fibril formation in model proteins were comprehensively analyzed using fluorescence lifetime and intensity of ThT, intrinsic fluorescence of proteinaceous fluorophores, and dbAF. For all systems, intensity enhancement of the dbAF band with similar spectral parameters (∼350 nm excitation; ∼450 nm emission) was observed. Although the time course of ThT lifetime (indicative of protofibrils formation) coincided with that of tyrosine residues in insulin, and the kinetic changes in the ThT fluorescence intensity (reflecting formation of mature fibrils) coincided with changes in ThT absorption spectrum, the dbAF band started to increase from the beginning of the incubation process without a lag-phase. Our mass-spectrometry data and model experiments suggested that dbAF could be at least partially related to oxidation of amino acids. This study scrutinizes the dbAF features in the context of the existing hypotheses about the origin of this spectral band.
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10
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Sirangelo I, Borriello M, Irace G, Iannuzzi C. Intrinsic blue-green fluorescence in amyloyd fibrils. AIMS BIOPHYSICS 2018. [DOI: 10.3934/biophy.2018.2.155] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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11
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Insights into Insulin Fibril Assembly at Physiological and Acidic pH and Related Amyloid Intrinsic Fluorescence. Int J Mol Sci 2017; 18:ijms18122551. [PMID: 29182566 PMCID: PMC5751154 DOI: 10.3390/ijms18122551] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/10/2017] [Accepted: 11/23/2017] [Indexed: 12/13/2022] Open
Abstract
Human insulin is a widely used model protein for the study of amyloid formation as both associated to insulin injection amyloidosis in type II diabetes and highly prone to form amyloid fibrils in vitro. In this study, we aim to gain new structural insights into insulin fibril formation under two different aggregating conditions at neutral and acidic pH, using a combination of fluorescence, circular dichroism, Fourier-transform infrared spectroscopy, and transmission electron miscroscopy. We reveal that fibrils formed at neutral pH are morphologically different from those obtained at lower pH. Moreover, differences in FTIR spectra were also detected. In addition, only insulin fibrils formed at neutral pH showed the characteristic blue-green fluorescence generally associated to amyloid fibrils. So far, the molecular origin of this fluorescence phenomenon has not been clarified and different hypotheses have been proposed. In this respect, our data provide experimental evidence that allow identifying the molecular origin of such intrinsic property.
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12
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Gan Z, Xu H. Photoluminescence of Diphenylalanine Peptide Nano/Microstructures: From Mechanisms to Applications. Macromol Rapid Commun 2017; 38. [DOI: 10.1002/marc.201700370] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 06/29/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Zhixing Gan
- Key Laboratory of Optoelectronic Technology of Jiangsu Province; School of Physics and Technology; Nanjing Normal University; Nanjing 210023 China
| | - Hao Xu
- Faculty of Science; Ningbo University; Ningbo 315211 China
- Advanced Light Microscopy; Royal Institute of Technology; Science for Life Laboratory; Solna SE-17121 Sweden
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13
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Grisanti L, Pinotsi D, Gebauer R, Kaminski Schierle GS, Hassanali AA. A computational study on how structure influences the optical properties in model crystal structures of amyloid fibrils. Phys Chem Chem Phys 2017; 19:4030-4040. [PMID: 28111679 PMCID: PMC7612978 DOI: 10.1039/c6cp07564a] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Amyloid fibrils have been shown to have peculiar optical properties since they can exhibit fluorescence in the absence of aromatic residues. In a recent study, we have shown that proton transfer (PT) events along hydrogen bonds (HBs) are coupled to absorption in the near UV range. Here, we gain more insights into the different types of hydrogen bonding interactions that occur in our model systems and the molecular factors that control the susceptibility of the protons to undergo PT and how this couples to the optical properties. In the case of the strong N-C termini interactions, a nearby methionine residue stabilizes the non-zwitterionic NH2-COOH pair, while zwitterionic NH3+-COO- is stabilized by the proximity of nearby crystallographic water molecules. Proton motion along the hydrogen bonds in the fibril is intimately coupled to the compression of the heavier atoms, similar to what is observed in bulk water. Small changes in the compression of the hydrogen bonds in the protein can lead to significant changes in both the ground and excited state potential energy surfaces associated with PT. Finally, we also reinforce the importance of nuclear quantum fluctuations of protons in the HBs of the amyloid proteins.
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Affiliation(s)
- Luca Grisanti
- International Centre for Theoretical Physics, Strada Costiera 11, Trieste 34151, Italy.
| | - Dorothea Pinotsi
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Ralph Gebauer
- International Centre for Theoretical Physics, Strada Costiera 11, Trieste 34151, Italy.
| | - Gabriele S Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Ali A Hassanali
- International Centre for Theoretical Physics, Strada Costiera 11, Trieste 34151, Italy.
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14
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Pinotsi D, Grisanti L, Mahou P, Gebauer R, Kaminski CF, Hassanali A, Kaminski Schierle GS. Proton Transfer and Structure-Specific Fluorescence in Hydrogen Bond-Rich Protein Structures. J Am Chem Soc 2016; 138:3046-57. [PMID: 26824778 DOI: 10.1021/jacs.5b11012] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Protein structures which form fibrils have recently been shown to absorb light at energies in the near UV range and to exhibit a structure-specific fluorescence in the visible range even in the absence of aromatic amino acids. However, the molecular origin of this phenomenon has so far remained elusive. Here, we combine ab initio molecular dynamics simulations and fluorescence spectroscopy to demonstrate that these intrinsically fluorescent protein fibrils are permissive to proton transfer across hydrogen bonds which can lower electron excitation energies and thereby decrease the likelihood of energy dissipation associated with conventional hydrogen bonds. The importance of proton transfer on the intrinsic fluorescence observed in protein fibrils is signified by large reductions in the fluorescence intensity upon either fully protonating, or deprotonating, the fibrils at pH = 0 or 14, respectively. Thus, our results point to the existence of a structure-specific fluorophore that does not require the presence of aromatic residues or multiple bond conjugation that characterize conventional fluorescent systems. The phenomenon may have a wide range of implications in biological systems and in the design of self-assembled functional materials.
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Affiliation(s)
- Dorothea Pinotsi
- Department of Chemical Engineering and Biotechnology, University of Cambridge , Pembroke Street, Cambridge CB2 3RA, United Kingdom
| | - Luca Grisanti
- International Centre for Theoretical Physics , Strada Costiera 11, Trieste 34151 Italy
| | - Pierre Mahou
- Department of Chemical Engineering and Biotechnology, University of Cambridge , Pembroke Street, Cambridge CB2 3RA, United Kingdom
| | - Ralph Gebauer
- International Centre for Theoretical Physics , Strada Costiera 11, Trieste 34151 Italy
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge , Pembroke Street, Cambridge CB2 3RA, United Kingdom
| | - Ali Hassanali
- International Centre for Theoretical Physics , Strada Costiera 11, Trieste 34151 Italy
| | - Gabriele S Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge , Pembroke Street, Cambridge CB2 3RA, United Kingdom
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15
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Chan FTS, Kaminski Schierle GS, Kumita JR, Bertoncini CW, Dobson CM, Kaminski CF. Protein amyloids develop an intrinsic fluorescence signature during aggregation. Analyst 2013; 138:2156-62. [PMID: 23420088 PMCID: PMC5360231 DOI: 10.1039/c3an36798c] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report observations of an intrinsic fluorescence in the visible range, which develops during the aggregation of a range of polypeptides, including the disease-related human peptides amyloid-β(1-40) and (1-42), lysozyme and tau. Characteristic fluorescence properties such as the emission lifetime and spectra were determined experimentally. This intrinsic fluorescence is independent of the presence of aromatic side-chain residues within the polypeptide structure. Rather, it appears to result from electronic levels that become available when the polypeptide chain folds into a cross-β sheet scaffold similar to what has been reported to take place in crystals. We use these findings to quantify protein aggregation in vitro by fluorescence imaging in a label-free manner.
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Affiliation(s)
- Fiona T. S. Chan
- Department of Chemical Engineering and Biotechnology, University of
Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, UK
| | - Gabriele S. Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of
Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, UK
| | - Janet R. Kumita
- Department of Chemistry, University of Cambridge, Lensfield Road,
Cambridge CB2 1EW, UK
| | - Carlos W. Bertoncini
- Institute for Research in Biomedicine, Baldiri Reixac 10, 08028,
Barcelona, Spain
| | - Christopher M. Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road,
Cambridge CB2 1EW, UK
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of
Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, UK
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Stepanenko OV, Verkhusha VV, Shavlovsky MM, Kuznetsova IM, Uversky VN, Turoverov KK. Understanding the role of Arg96 in structure and stability of green fluorescent protein. Proteins 2008; 73:539-51. [PMID: 18470931 DOI: 10.1002/prot.22089] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Arg96 is a highly conservative residue known to catalyze spontaneous green fluorescent protein (GFP) chromophore biosynthesis. To understand a role of Arg96 in conformational stability and structural behavior of EGFP, the properties of a series of the EGFP mutants bearing substitutions at this position were studied using circular dichroism, steady state fluorescence spectroscopy, fluorescence lifetime, kinetics and equilibrium unfolding analysis, and acrylamide-induced fluorescence quenching. During the protein production and purification, high yield was achieved for EGFP/Arg96Cys variant, whereas EGFP/Arg96Ser and EGFP/Arg96Ala were characterized by essentially lower yields and no protein was produced when Arg96 was substituted by Gly. We have also shown that only EGFP/Arg96Cys possessed relatively fast chromophore maturation, whereas it took EGFP/Arg96Ser and EGFP/Arg96Ala about a year to develop a noticeable green fluorescence. The intensity of the characteristic green fluorescence measured for the EGFP/Arg96Cys and EGFP/Arg96Ser (or EGFP/Arg96Ala) was 5- and 50-times lower than that of the nonmodified EGFP. Intriguingly, EGFP/Arg96Cys was shown to be more stable than EGFP toward the GdmCl-induced unfolding both in kinetics and in the quasi-equilibrium experiments. In comparison with EGFP, tryptophan residues of EGFP/Arg96Cys were more accessible to the solvent. These data taken together suggest that besides established earlier crucial catalytic role, Arg96 is important for the overall folding and conformational stability of GFP.
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Affiliation(s)
- Olesya V Stepanenko
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
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