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Horvath I, Welte H, Schmit JD, Kovermann M, Wittung-Stafshede P. Distinct growth regimes of α-synuclein amyloid elongation. Biophys J 2023; 122:2556-2563. [PMID: 37170496 PMCID: PMC10323017 DOI: 10.1016/j.bpj.2023.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/28/2023] [Accepted: 05/08/2023] [Indexed: 05/13/2023] Open
Abstract
Addition of amyloid seeds to aggregation-prone monomers allows for amyloid fiber growth (elongation) omitting slow nucleation. We here combine Thioflavin T fluorescence (probing formation of amyloids) and solution-state NMR spectroscopy (probing disappearance of monomers) to assess elongation kinetics of the amyloidogenic protein, α-synuclein, for which aggregation is linked to Parkinson's disease. We found that both spectroscopic detection methods give similar kinetic results, which can be fitted by applying double exponential decay functions. When the origin of the two-phase behavior was analyzed by mathematical modeling, parallel paths as well as stop-and-go behavior were excluded as possible explanations. Instead, supported by previous theory, the experimental elongation data reveal distinct kinetic regimes that depend on instantaneous monomer concentration. At low monomer concentrations (toward end of experiments), amyloid growth is limited by conformational changes resulting in β-strand alignments. At the higher monomer concentrations (initial time points of experiments), growth occurs rapidly by incorporating monomers that have not successfully completed the conformational search. The presence of a fast disordered elongation regime at high monomer concentrations agrees with coarse-grained simulations and theory but has not been detected experimentally before. Our results may be related to the wide range of amyloid folds observed.
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Affiliation(s)
- Istvan Horvath
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Hannah Welte
- Department of Chemistry, University of Konstanz, Konstanz, Germany
| | - Jeremy D Schmit
- Department of Physics, Kansas State University, Manhattan, Kansas.
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2
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Insights into the cross-amyloid aggregation of Aβ40 and its N-terminal truncated peptide Aβ11-40 affected by epigallocatechin gallate. Chin J Chem Eng 2022. [DOI: 10.1016/j.cjche.2021.04.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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3
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Noi K, Ikenaka K, Mochizuki H, Goto Y, Ogi H. Disaggregation Behavior of Amyloid β Fibrils by Anthocyanins Studied by Total-Internal-Reflection-Fluorescence Microscopy Coupled with a Wireless Quartz-Crystal Microbalance Biosensor. Anal Chem 2021; 93:11176-11183. [PMID: 34351734 DOI: 10.1021/acs.analchem.1c01720] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Amyloid fibrils are formed from various proteins, some of which cause the corresponding neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. It has been reported that many compounds inhibit the formation of amyloid fibrils. Anthocyanins are flavonoid pigments present in fruits and vegetables, which are known to suppress symptoms related with Alzheimer's disease. However, the influence of anthocyanins on the amyloid fibril remains unclear. Here, we succeeded in the direct monitoring of the disaggregation reaction of single amyloid β (Aβ) fibrils by anthocyanins using total-internal-reflection-fluorescence microscopy with a quartz-crystal microbalance (TIRFM-QCM). It is found that the disassembly activity to the Aβ fibrils depends on the number of hydroxyl groups in six-membered ring B of anthocyanin, and only delphinidin-3-galactoside, possessing three hydroxyl groups there, shows high disassembly activity. Our results show the importance of the number of hydroxyl groups and demonstrate the usefulness of TIRFM-QCM as a powerful tool in studying interactions between amyloid fibrils and compounds.
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Affiliation(s)
- Kentaro Noi
- Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kensuke Ikenaka
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuji Goto
- Global Center for Medical Engineering and Informatics, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hirotsugu Ogi
- Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
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4
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Mobed A, Hasanzadeh M. Biosensing: The best alternative for conventional methods in detection of Alzheimer's disease biomarkers. Int J Biol Macromol 2020; 161:59-71. [PMID: 32504710 DOI: 10.1016/j.ijbiomac.2020.05.257] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 11/29/2022]
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5
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The growth of amyloid fibrils: rates and mechanisms. Biochem J 2019; 476:2677-2703. [DOI: 10.1042/bcj20160868] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/08/2019] [Accepted: 09/10/2019] [Indexed: 12/19/2022]
Abstract
AbstractAmyloid fibrils are β-sheet-rich linear protein polymers that can be formed by a large variety of different proteins. These assemblies have received much interest in recent decades, due to their role in a range of human disorders. However, amyloid fibrils are also found in a functional context, whereby their structural, mechanical and thermodynamic properties are exploited by biological systems. Amyloid fibrils form through a nucleated polymerisation mechanism with secondary processes acting in many cases to amplify the number of fibrils. The filamentous nature of amyloid fibrils implies that the fibril growth rate is, by several orders of magnitude, the fastest step of the overall aggregation reaction. This article focusses specifically on in vitro experimental studies of the process of amyloid fibril growth, or elongation, and summarises the state of knowledge of its kinetics and mechanisms. This work attempts to provide the most comprehensive summary, to date, of the available experimental data on amyloid fibril elongation rate constants and the temperature and concentration dependence of amyloid fibril elongation rates. These data are compared with those from other types of protein polymers. This comparison with data from other polymerising proteins is interesting and relevant because many of the basic ideas and concepts discussed here were first introduced for non-amyloid protein polymers, most notably by the Japanese school of Oosawa and co-workers for cytoskeletal filaments.
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Hao X, Zheng J, Sun Y, Dong X. Seeding and Cross-Seeding Aggregations of Aβ 40 and Its N-Terminal-Truncated Peptide Aβ 11-40. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2821-2831. [PMID: 30681866 DOI: 10.1021/acs.langmuir.8b03599] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In the amyloid plaques of Alzheimer's disease (AD) patients, a large number of N-terminal-truncated amyloid β (Aβ) peptides such as Aβ11-40 have been identified in addition to the full-length Aβ peptides. However, little is known about the roles of the N-terminal-truncated peptides in AD pathological process. Herein, seeding and cross-seeding aggregations of Aβ40 and its N-terminal-truncated Aβ11-40 were investigated in the solution and on the surfaces of chips with immobilized seeds by extensive biophysical and biological analyses. The results showed that Aβ40 and Aβ11-40 aggregates could seed both homologous and heterologous aggregations of the two monomers. However, the capability and characteristics of the seeding (homologous aggregation) and cross-seeding (heterologous aggregation) were significantly different. Aβ40 seeds showed stronger acceleration effects on the aggregations than Aβ11-40 seeds and induced β-sheet-rich fibrous aggregates of similar cytotoxicities for the two monomers. This indicates that Aβ40 and Aβ11-40 had similar aggregation pathways in the seeding and cross-seeding on Aβ40 seeds. By contrast, Aβ11-40 seeds led to different aggregation pathways of Aβ40 and Aβ11-40. Pure Aβ11-40 aggregates had higher toxicity than Aβ40 aggregates, and as seeds, Aβ11-40 seeds induced Aβ40 to form aggregates of higher cytotoxicity. However, homologous Aβ11-40 aggregates induced by Aβ11-40 seeds showed lower cytotoxicity than pure Aβ11-40 aggregates. The results suggest that Aβ11-40 plays an important role in the pathological process of AD.
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Affiliation(s)
- Xiuping Hao
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China
| | - Jie Zheng
- Department of Chemical and Biomolecular Engineering , The University of Akron , Akron , Ohio 44325 , United States
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China
| | - Xiaoyan Dong
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China
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7
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Lai YT, Ogi H, Noi K, Kato F. Viscoelasticity Response during Fibrillation of Amyloid β Peptides on a Quartz-Crystal-Microbalance Biosensor. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5474-5479. [PMID: 29697982 DOI: 10.1021/acs.langmuir.8b00639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Unlike previous in vitro measurements where Amyloid β (Aβ) aggregation was studied in bulk solutions, we detect the structure change of the Aβ aggregate on the surface of a wireless quartz-crystal-microbalance biosensor, which resembles more closely the aggregation process on the cell membrane. Using a 58 MHz quartz crystal, we monitored changes in the viscoelastic properties of the aggregate formed on the quartz surface from monomers to oligomers and then to fibrils, involving up to the 7th overtone mode (406 MHz). With atomic-force microscopy observations, we found a significant stiffness increase as well as thinning of the protein layer during the structure change from oligomer to fibrils at 20 h, which indicates that the stiffness of the fibril is much higher. Viscoelasticity can provide a significant index of fibrillation and can be useful for evaluating inhibitory medicines in drug development.
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Affiliation(s)
- Yen-Ting Lai
- Graduate School of Engineering Science , Osaka University , Toyonaka , Osaka 560-8531 , Japan
| | - Hirotsugu Ogi
- Graduate School of Engineering , Osaka University , Suita , Osaka 565-0871 , Japan
| | - Kentaro Noi
- Graduate School of Engineering , Osaka University , Suita , Osaka 565-0871 , Japan
| | - Fumihito Kato
- Department of Mechanical Engineering , Nippon Institute of Technology , 4-1 Gakuendai , Minamisaitama-gun, Saitama 345-8501 , Japan
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8
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Study of Alzheimer's Disease-Related Biophysical Kinetics with a Microslit-Embedded Cantilever Sensor in a Liquid Environment. SENSORS 2017; 17:s17081819. [PMID: 28783132 PMCID: PMC5579575 DOI: 10.3390/s17081819] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 08/03/2017] [Accepted: 08/05/2017] [Indexed: 11/17/2022]
Abstract
A microsized slit-embedded cantilever sensor (slit cantilever) was fabricated and evaluated as a biosensing platform in a liquid environment. In order to minimize the degradation caused by viscous damping, a 300 × 100 µm2 (length × width) sized cantilever was released by a 5 µm gap-surrounding and vibrated by an internal piezoelectric-driven self-actuator. Owing to the structure, when the single side of the slit cantilever was exposed to liquid a significant quality factor (Q = 35) could be achieved. To assess the sensing performance, the slit cantilever was exploited to study the biophysical kinetics related to Aβ peptide. First, the quantification of Aβ peptide with a concentration of 10 pg/mL to 1 μg/mL was performed. The resonant responses exhibited a dynamic range from 100 pg/mL to 100 ng/mL (−56.5 to −774 ΔHz) and a dissociation constant (KD) of binding affinity was calculated as 1.75 nM. Finally, the Aβ self-aggregation associated with AD pathogenesis was monitored by adding monomeric Aβ peptides. As the concentration of added analyte increased from 100 ng/mL to 10 µg/mL, both the frequency shift values (−813 to −1804 ΔHz) and associate time constant increased. These results showed the excellent sensing performance of the slit cantilever overcoming a major drawback in liquid environments to become a promising diagnostic tool candidate.
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Hwang HJ, Ryu MY, Park CY, Ahn J, Park HG, Choi C, Ha SD, Park TJ, Park JP. High sensitive and selective electrochemical biosensor: Label-free detection of human norovirus using affinity peptide as molecular binder. Biosens Bioelectron 2016; 87:164-170. [PMID: 27551996 DOI: 10.1016/j.bios.2016.08.031] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/01/2016] [Accepted: 08/11/2016] [Indexed: 12/18/2022]
Abstract
Norovirus is known as the major cause of highly infection for gastrointestinal tracts. In this study, robust and highly sensitive biosensors for detecting human norovirus by employing a recognition affinity peptide-based electrochemical platform were described. A series of amino acid-substituted and cysteine-incorporated recognition peptides isolated from evolutionary phage display technique was chemically synthesized and immobilized to a gold sensor layer, the detection performance of the gold-immobilized synthetic peptide-based sensor system was assessed using QCM, CV and EIS. Using EIS, the limit of detection with Noro-1 as a molecular binder was found to be 99.8nM for recombinant noroviral capsid proteins (rP2) and 7.8copies/mL for human norovirus, thereby demonstrating a high degree of sensitivity for their corresponding targets. These results suggest that a biosensor which consists of affinity peptides as a molecular binder and miniaturized microdevices as diagnostic tool could be served as a new type of biosensing platform for point-of-care testing.
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Affiliation(s)
- Hye Jin Hwang
- Department of Pharmaceutical Engineering, Daegu Haany University, Gyeongsan 38610, Republic of Korea
| | - Myung Yi Ryu
- Department of Pharmaceutical Engineering, Daegu Haany University, Gyeongsan 38610, Republic of Korea
| | - Chan Young Park
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Junki Ahn
- Department of Chemical and Biomolecular Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Hyun Gyu Park
- Department of Chemical and Biomolecular Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Changsun Choi
- Department of Food and Nutrition, School of Food Science and Technology, Chung-Ang University, Ansung 17546, Republic of Korea
| | - Sang-Do Ha
- Department of Food Science and Technology, School of Food Science and Technology, Chung-Ang University, Ansung 17546, Republic of Korea
| | - Tae Jung Park
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea.
| | - Jong Pil Park
- Department of Pharmaceutical Engineering, Daegu Haany University, Gyeongsan 38610, Republic of Korea.
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10
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Wang C, Xu L, Cheng F, Wang H, Jia L. Curcumin induces structural change and reduces the growth of amyloid-β fibrils: a QCM-D study. RSC Adv 2015. [DOI: 10.1039/c5ra02314a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Curcumin inhibited Aβ fibril growth through leading to the structural conversion of the growing fibril to a more loosely constructed aggregate.
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Affiliation(s)
- Conggang Wang
- School of Life Science and Biotechnology
- Dalian University of Technology
- Dalian 116023
- P. R. China
| | - Li Xu
- School of Life Science and Biotechnology
- Dalian University of Technology
- Dalian 116023
- P. R. China
| | - Fang Cheng
- School of Pharmaceutical Science and Technology
- Dalian University of Technology
- Dalian 116023
- P. R. China
| | - Hanqi Wang
- School of Pharmaceutical Science and Technology
- Dalian University of Technology
- Dalian 116023
- P. R. China
| | - Lingyun Jia
- School of Life Science and Biotechnology
- Dalian University of Technology
- Dalian 116023
- P. R. China
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11
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Ogi H, Fukukshima M, Hamada H, Noi K, Hirao M, Yagi H, Goto Y. Ultrafast propagation of β-amyloid fibrils in oligomeric cloud. Sci Rep 2014; 4:6960. [PMID: 25376301 PMCID: PMC4223663 DOI: 10.1038/srep06960] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 10/22/2014] [Indexed: 11/13/2022] Open
Abstract
Interaction between monomer peptides and seeds is essential for clarifying the fibrillation mechanism of amyloid β (Aβ) peptides. We monitored the deposition reaction of Aβ1–40 peptides on immobilized seeds grown from Aβ1–42, which caused formation of oligomers in the early stage. The deposition reaction and fibrillation procedure were monitored throughout by novel total-internal-reflection-fluorescence microscopy with a quartz-crystal microbalance (TIRFM-QCM) system. This system allows simultaneous evaluation of the amount of deposited peptides on the surface seeds by QCM and fibril nucleation and elongation by TIRFM. Most fibrils reached other nuclei, forming the fibril network across the nucleus hubs in a short time. We found a fibril-elongation rate two-orders-of-magnitude higher in an oligomeric cloud than reported values, indicating ultrafast transition of oligomers into fibrils.
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Affiliation(s)
- Hirotsugu Ogi
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Masahiko Fukukshima
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hiroki Hamada
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kentaro Noi
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Masahiko Hirao
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hisashi Yagi
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan
| | - Yuji Goto
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan
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12
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Kurzątkowska K, Ostatná V, Hamley IW, Doneux T, Paleček E. Electrochemical sensing of 2D condensation in amyloid peptides. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.05.057] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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13
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Effect of peptide secondary structure on adsorption and adsorbed film properties. Acta Biomater 2013; 9:6403-13. [PMID: 23376129 DOI: 10.1016/j.actbio.2013.01.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 01/07/2013] [Accepted: 01/12/2013] [Indexed: 01/15/2023]
Abstract
Protein adsorption at the biomaterial-tissue interface is of utmost importance to the widespread application of engineered materials. The present study asked what role the secondary structures of peptides play in their adsorption, as well as how these structures affect the physicochemical properties of the final adsorbed layer. To this end, α-helices and β-sheets were induced in poly-l-lysine, and their adsorption to Au surfaces was monitored using quartz crystal microbalance with dissipation. It was observed that secondary structures played an important role in governing both the adsorption process and the final film properties. Higher initial adsorption rates were obtained for α-helices compared with β-sheets, regardless of solution salt concentration. Adsorption half-time for β-sheets was greater than that for α-helices, and the final amount adsorbed on β-sheet was significantly higher than that on α-helix. The adsorbed amount and adsorption half-time decreased with increasing salt concentration, suggesting that electrostatic interactions played a role. It was found that the differences in Zeta potential coupled with the apparent effect of surface contact area differences between α-helix and β-sheet conformations are ultimately responsible for these different peptide adsorption behaviours at the Au interface. The initial adsorption rate of α-helix increased with salt concentrations up to 50mM, whereas β-sheet initial adsorption rates increased with salt concentrations up to 500 mM. Viscosities for films formed from α-helices were about twice those of β-sheets films, regardless of solution ionic strength. It was evident that the peptide secondary structures influence all aspects of their adsorption, as well as affecting the adsorbed film properties.
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Ogi H, Fukushima M, Uesugi K, Yagi H, Goto Y, Hirao M. Acceleration of deposition of Aβ1−40 peptide on ultrasonically formed Aβ1−42 nucleus studied by wireless quartz-crystal-microbalance biosensor. Biosens Bioelectron 2013; 40:200-5. [DOI: 10.1016/j.bios.2012.07.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/30/2012] [Accepted: 07/13/2012] [Indexed: 11/26/2022]
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15
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Lee YH, Goto Y. Kinetic intermediates of amyloid fibrillation studied by hydrogen exchange methods with nuclear magnetic resonance. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1307-23. [DOI: 10.1016/j.bbapap.2012.07.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/24/2012] [Accepted: 07/26/2012] [Indexed: 01/28/2023]
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16
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García S, Cuscó C, Brissos RF, Torrents E, Caubet A, Gamez P. Dual role of Cu²⁺ ions on the aggregation and degradation of soluble Aβ oligomers and protofibrils investigated by fluorescence spectroscopy and AFM. J Inorg Biochem 2012; 116:26-36. [PMID: 23010326 DOI: 10.1016/j.jinorgbio.2012.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/11/2012] [Accepted: 07/05/2012] [Indexed: 11/20/2022]
Abstract
The neuropathological character of copper(II) ions (Cu(2+)) upon interaction with soluble human amyloid-β(1-42) that subsequently generates senile plaques and/or reactive oxygen species (ROS) is considered as one of the very important features of Alzheimer's disease. The present study carried out by using fluorescence spectroscopy and atomic-force microscopy (AFM) indeed confirms the dual role played by Cu(2+), namely as mediator of protein aggregation and as generator of ROS leading to irreversible protein alteration, which most likely involve two distinct copper-binding sites. The AFM investigations clearly evidence the copper-induced aggregation of Aβ oligomers and protofibrils, while comparative fluorescence measurements with copper and zinc reveals the crucial involvement of redox-active copper in the generation of Aβ-cross-linked structures.
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Affiliation(s)
- Silvia García
- Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
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