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Bowers SR, Lockhart C, Klimov DK. Replica Exchange with Hybrid Tempering Efficiently Samples PGLa Peptide Binding to Anionic Bilayer. J Chem Theory Comput 2023; 19:6532-6550. [PMID: 37676235 DOI: 10.1021/acs.jctc.3c00787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
We evaluated the utility of a variant of the replica exchange method, a replica exchange with hybrid tempering (REHT), for all-atom explicit water biomolecular simulations and compared it with a more traditional replica exchange with the solute tempering (REST) algorithm. As a test system, we selected a 21-mer antimicrobial peptide PGLa binding to an anionic DMPC/DMPG lipid bilayer. Application of REHT revealed the following binding mechanism. Due to the strong hydrophobic moment, the bound PGLa adopts an extensive helical structure. The binding free energy landscape identifies two major bound states, a metastable surface bound state and a dominant inserted state. In both states, positively charged PGLa amino acids maintain electrostatic interactions with anionic phosphate groups by rotating the PGLa helix around its axis. PGLa binding causes an influx of anionic DMPG and an efflux of zwitterionic DMPC lipids from the peptide proximity. PGLa thins the bilayer and disorders the adjacent fatty acid tails. Deep invasion of water wires into the bilayer hydrophobic core is detected in the inserted peptide state. The analysis of charge density distributions indicated that peptide positive charges are nearly compensated for by lipid negative charges and water dipole ordering, whereas ions play no role in peptide binding. Thus, electrostatic interactions are the key energetic factor in binding cationic PGLa to an anionic DMPC/DMPG bilayer. Comparison of REHT and REST shows that due to exclusion of lipids from tempered partition, REST lags behind REHT in peptide equilibration, particularly, with respect to peptide insertion and helix acquisition. As a result, REST struggles to provide accurate details of PGLa binding, although it still qualitatively maps the bimodal binding mechanism. Importantly, REHT not only equilibrates PGLa in the bilayer faster than REST, but also with less computational effort. We conclude that REHT is a preferable choice for studying interfacial biomolecular systems.
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Affiliation(s)
- Steven R Bowers
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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2
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Examination of Adsorption Orientation of Amyloidogenic Peptides Over Nano-Gold Colloidal Particle Surfaces. Int J Mol Sci 2019; 20:ijms20215354. [PMID: 31661810 PMCID: PMC6862242 DOI: 10.3390/ijms20215354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/14/2019] [Accepted: 10/23/2019] [Indexed: 01/12/2023] Open
Abstract
The adsorption of amyloidogenic peptides, amyloid beta 1–40 (Aβ1–40), alpha-synuclein (α-syn), and beta 2 microglobulin (β2m), was attempted over the surface of nano-gold colloidal particles, ranging from d = 10 to 100 nm in diameter (d). The spectroscopic inspection between pH 2 and pH 12 successfully extracted the critical pH point (pHo) at which the color change of the amyloidogenic peptide-coated nano-gold colloids occurred due to aggregation of the nano-gold colloids. The change in surface property caused by the degree of peptide coverage was hypothesized to reflect the ΔpHo, which is the difference in pHo between bare gold colloids and peptide coated gold colloids. The coverage ratio (Θ) for all amyloidogenic peptides over gold colloid of different sizes was extracted by assuming Θ = 0 at ΔpHo = 0. Remarkably, Θ was found to have a nano-gold colloidal size dependence, however, this nano-size dependence was not simply correlated with d. The geometric analysis and simulation of reproducing Θ was conducted by assuming a prolate shape of all amyloidogenic peptides. The simulation concluded that a spiking-out orientation of a prolate was required in order to reproduce the extracted Θ. The involvement of a secondary layer was suggested; this secondary layer was considered to be due to the networking of the peptides. An extracted average distance of networking between adjacent gold colloids supports the binding of peptides as if they are “entangled” and enclosed in an interfacial distance that was found to be approximately 2 nm. The complex nano-size dependence of Θ was explained by available spacing between adjacent prolates. When the secondary layer was formed, Aβ1–40 and α-syn possessed a higher affinity to a partially negative nano-gold colloidal surface. However, β2m peptides tend to interact with each other. This difference was explained by the difference in partial charge distribution over a monomer. Both Aβ1–40 and α-syn are considered to have a partial charge (especially δ+) distribution centering around the prolate axis. The β2m, however, possesses a distorted charge distribution. For a lower Θ (i.e., Θ <0.5), a prolate was assumed to conduct a gyration motion, maintaining the spiking-out orientation to fill in the unoccupied space with a tilting angle ranging between 5° and 58° depending on the nano-scale and peptide coated to the gold colloid.
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Hashemi M, Zhang Y, Lv Z, Lyubchenko YL. Spontaneous self-assembly of amyloid β (1-40) into dimers. NANOSCALE ADVANCES 2019; 1:3892-3899. [PMID: 36132110 PMCID: PMC9417245 DOI: 10.1039/c9na00380k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/16/2019] [Indexed: 05/17/2023]
Abstract
The self-assembly and fibrillation of amyloid β (Aβ) proteins is the neuropathological hallmark of Alzheimer's disease. However, the molecular mechanism of how disordered monomers assemble into aggregates remains largely unknown. In this work, we characterize the assembly of Aβ (1-40) monomers into dimers using long-time molecular dynamics simulations. Upon interaction, the monomers undergo conformational transitions, accompanied by change of the structure, leading to the formation of a stable dimer. The dimers are stabilized by interactions in the N-terminal region (residues 5-12), in the central hydrophobic region (residues 16-23), and in the C-terminal region (residues 30-40); with inter-peptide interactions focused around the N- and C-termini. The dimers do not contain long β-strands that are usually found in fibrils.
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Affiliation(s)
- Mohtadin Hashemi
- Department of Pharmaceutical Sciences, 986025 Nebraska Medical Center, University of Nebraska Medical Center Omaha NE 68198 USA
| | - Yuliang Zhang
- Department of Pharmaceutical Sciences, 986025 Nebraska Medical Center, University of Nebraska Medical Center Omaha NE 68198 USA
- Biology and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory Livermore CA 94550 USA
| | - Zhengjian Lv
- Department of Pharmaceutical Sciences, 986025 Nebraska Medical Center, University of Nebraska Medical Center Omaha NE 68198 USA
- Bruker Nano Surfaces Division 112 Robin Hill Road Goleta, Santa Barbara CA 93117 USA
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, 986025 Nebraska Medical Center, University of Nebraska Medical Center Omaha NE 68198 USA
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Li H, Wang X, Yu H, Zhu J, Jin H, Wang A, Yang Z. Combining in vitro and in silico Approaches to Find New Candidate Drugs Targeting the Pathological Proteins Related to the Alzheimer's Disease. Curr Neuropharmacol 2018; 16:758-768. [PMID: 29086699 PMCID: PMC6080099 DOI: 10.2174/1570159x15666171030142108] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 09/24/2017] [Accepted: 10/10/2017] [Indexed: 01/10/2023] Open
Abstract
Background: Alzheimer’s disease (AD) as the most common cause of dementia among older people has aroused the universal concern of the whole world. However, until now there is still none effective treatments. Consequently, the development of new drugs targeting this complicated brain disorder is urgent and needs more efforts. In this review, we detailed the current state of knowledge about new candidate drugs targeting the pathological proteins especially the drugs which are employed using the combined methods of in vitro and in silico. Methods: We looked up and reviewed online papers related to the pathogenesis and new drugs development of AD. Then, articles up to the requirements were respectively analyzed and summaried to provide the latest knowledge about the pathogenic effect and the new candidate drugs targeting Aβ and Tau proteins. Results: New candidate drugs targeting the Aβ include decreasing the production, promoting the clearence and preventing aggregation. However these drugs have mostly failed in Phase III clinical trial stage due to the unsuccessful of reversing cognition symptoms. As to tau protein, the prevention of tau aggregation and propagation is a promising strategy to synthesize/design mechanism-based drugs against tauopathies. Some candidate drugs are under research. Moreover, because of the complex pathogenesis of AD, multi-target drugs have also shed light on the treatment of AD. Conclusion: Given to the consecutive failure of Aβ-directed drugs and the feasibilities of tau-targeted therapy, more and more researchers suggested that the AD treatment should be moved from Aβ to tau or focused on considering the soluble form of Aβ and tau as a whole. Moreover, the novel in silico methods also have great potential in drug discovery, drug repositioning, virtual screening of chemical libraries. No matter how many difficulties and challenges in prevention and treatment of AD, we firmly believe that the effective and safe drugs will be found using the combined methods in the immediate future with the global effort.
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Affiliation(s)
- Hui Li
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Xiaobing Wang
- Tumor Marker Research Center, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Hongmei Yu
- China-Japan Union Hospital of Jilin University, Changchun, Jilin, 130021, China
| | - Jing Zhu
- College of Pharmacy, The Ohio State University, Columbus, Ohio, 43210, United States
| | - Hongtao Jin
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Aiping Wang
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Zhaogang Yang
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, 43210, United States
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5
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Etersalate prevents the formations of 6Aβ16-22 oligomer: An in silico study. PLoS One 2018; 13:e0204026. [PMID: 30226897 PMCID: PMC6143259 DOI: 10.1371/journal.pone.0204026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 09/01/2018] [Indexed: 11/19/2022] Open
Abstract
Oligomerization of amyloid beta (Aβ) peptides has been considered as the crucially causative agent in the development of Alzheimer's disease. Etersalate, a nonsteroidal anti-inflammatory oral drug (United State Food and Drug Administration—Unique Ingredient Identifier: 653GN04T2G) was previously suggested to bind well to proto-fibrils of Aβ peptides in silico. Here, the effect of etersalate on the oligomerization of soluble Aβ16–22 hexamer (6Aβ16–22) were extensively investigated using temperature replica exchange molecular dynamics (REMD) simulations over ~16.8 μs in total for 48 replicas (350 ns per replica). The results reveal that etersalate can enter the inner space or bind on the surface of 6Aβ16–22 conformations, which destabilizes the hexamer. Etersalate was predicted to able to cross the blood brain barrier using prediction of absorption, distribution, metabolism, and excretion—toxicity (preADMET) tools. Overall, although the investigation was performed with the low concentration of trial inhibitor, the obtained results indicate that etersalate is a potential drug candidate for AD through inhibiting formation of Aβ oligomers with the average binding free energy of -11.7 kcal/mol.
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7
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Ngo ST, Nguyen MT, Nguyen NT, Vu VV. The Effects of A21G Mutation on Transmembrane Amyloid Beta (11–40) Trimer: An In Silico Study. J Phys Chem B 2017; 121:8467-8474. [DOI: 10.1021/acs.jpcb.7b05906] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Son Tung Ngo
- Computational
Chemistry Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
- Faculty
of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
| | - Minh Tung Nguyen
- Binh Duong University, Thu Dau Mot City, Binh Duong Province, Vietnam
| | - Nguyen Thanh Nguyen
- Department
of Theoretical Physics, University of Science, Ho Chi Minh City, Vietnam
| | - Van V. Vu
- NTT
Hi-Tech Institute, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam
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8
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EGCG inhibits the oligomerization of amyloid beta (16-22) hexamer: Theoretical studies. J Mol Graph Model 2017; 76:1-10. [PMID: 28658644 DOI: 10.1016/j.jmgm.2017.06.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/16/2017] [Accepted: 06/19/2017] [Indexed: 11/21/2022]
Abstract
An extensive replica exchange molecular dynamics (REMD) simulation was performed to investigate the progress patterns of the inhibition of (-)-epigallocatechin-3-gallate (EGCG) on the Aβ16-22 hexamer. Structural variations of the oligomers without and with EGCG were monitored and analyzed in detail. It has been found that EGCG prevents the formation of Aβ oligomer through two different ways by either accelerating the Aβ oligomerization or reducing the β-content of the hexamer. It also decreases the potential "highly toxic" conformations of Aβ oligomer, which is related to the conformations having high order β-sheet sizes. Both electrostatic and van der Waals interaction energies are found to be involved to the binding process. Computed results using quantum chemical methods show that the π-π stacking is a critical factor of the interaction between EGCG and the peptides. As a result, the binding free energy of the EGCG to the Aβ peptides is slightly larger than that of the curcumin.
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9
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Nano-assembly of amyloid β peptide: role of the hairpin fold. Sci Rep 2017; 7:2344. [PMID: 28539626 PMCID: PMC5443804 DOI: 10.1038/s41598-017-02454-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022] Open
Abstract
Structural investigations have revealed that β hairpin structures are common features in amyloid fibrils, suggesting that these motifs play an important role in amyloid assembly. To test this hypothesis, we characterized the effect of the hairpin fold on the aggregation process using a model β hairpin structure, consisting of two Aβ(14–23) monomers connected by a turn forming YNGK peptide. AFM studies of the assembled aggregates revealed that the hairpin forms spherical structures whereas linear Aβ(14–23) monomers form fibrils. Additionally, an equimolar mixture of the monomer and the hairpin assembles into non-fibrillar aggregates, demonstrating that the hairpin fold dramatically changes the morphology of assembled amyloid aggregates. To understand the molecular mechanism underlying the role of the hairpin fold on amyloid assembly, we performed single-molecule probing experiments to measure interactions between hairpin and monomer and two hairpin complexes. The studies reveal that the stability of hairpin-monomer complexes is much higher than hairpin-hairpin complexes. Molecular dynamics simulations revealed a novel intercalated complex for the hairpin and monomer and Monte Carlo modeling further demonstrated that such nano-assemblies have elevated stability compared with stability of the dimer formed by Aβ(14–23) hairpin. The role of such folding on the amyloid assembly is also discussed.
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10
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Ngo ST, Hung HM, Tran KN, Nguyen MT. Replica exchange molecular dynamics study of the amyloid beta (11–40) trimer penetrating a membrane. RSC Adv 2017. [DOI: 10.1039/c6ra26461a] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The transmembrane Aβ11–40 trimer is investigated for the first time using REMD and FEP.
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Affiliation(s)
- Son Tung Ngo
- Computational Chemistry Research Group
- Ton Duc Thang University
- Ho Chi Minh City
- Vietnam
- Faculty of Applied Sciences
| | | | - Khoa Nhat Tran
- Department of Biological Sciences
- University of Maryland Baltimore County
- 21250 Baltimore
- USA
| | - Minh Tho Nguyen
- Computational Chemistry Research Group
- Ton Duc Thang University
- Ho Chi Minh City
- Vietnam
- Faculty of Applied Sciences
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11
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Ngo ST, Luu XC, Nguyen MT, Le CN, Vu VV. In silico studies of solvated F19W amyloid β (11–40) trimer. RSC Adv 2017. [DOI: 10.1039/c7ra07187f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
REMD studies shows that F19W mutation does not change in the overall structure of Aβ11–40 trimer significantly but increases it flexibility, consistent with the observed formation of the same fibril structures at slower rates.
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Affiliation(s)
- Son Tung Ngo
- Computational Chemistry Research Group
- Ton Duc Thang University
- Ho Chi Minh City
- Vietnam
- Faculty of Applied Sciences
| | - Xuan-Cuong Luu
- NTT Hi-Tech Institute
- Nguyen Tat Thanh University
- Ho Chi Minh City
- Vietnam
| | | | - Chinh N. Le
- NTT Hi-Tech Institute
- Nguyen Tat Thanh University
- Ho Chi Minh City
- Vietnam
| | - Van V. Vu
- NTT Hi-Tech Institute
- Nguyen Tat Thanh University
- Ho Chi Minh City
- Vietnam
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12
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Ngo ST, Hung HM, Truong DT, Nguyen MT. Replica exchange molecular dynamics study of the truncated amyloid beta (11–40) trimer in solution. Phys Chem Chem Phys 2017; 19:1909-1919. [DOI: 10.1039/c6cp05511g] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure of the 3Aβ11–40 oligomer is determined for the first time using T-REMD simulations.
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Affiliation(s)
- Son Tung Ngo
- Computational Chemistry Research Group
- Ton Duc Thang University
- Ho Chi Minh City
- Vietnam
- Faculty of Applied Sciences
| | | | - Duc Toan Truong
- Department of Theoretical Physics
- Ho Chi Minh City University of Science
- Ho Chi Minh City
- Vietnam
| | - Minh Tho Nguyen
- Computational Chemistry Research Group
- Ton Duc Thang University
- Ho Chi Minh City
- Vietnam
- Faculty of Applied Sciences
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13
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Liu J, Yang B, Ke J, Li W, Suen WC. Antibody-Based Drugs and Approaches Against Amyloid-β Species for Alzheimer’s Disease Immunotherapy. Drugs Aging 2016; 33:685-697. [DOI: 10.1007/s40266-016-0406-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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14
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Smith AK, Lockhart C, Klimov DK. Does Replica Exchange with Solute Tempering Efficiently Sample Aβ Peptide Conformational Ensembles? J Chem Theory Comput 2016; 12:5201-5214. [DOI: 10.1021/acs.jctc.6b00660] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Amy K. Smith
- School
of Systems Biology
and Computational Materials Science Center, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School
of Systems Biology
and Computational Materials Science Center, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School
of Systems Biology
and Computational Materials Science Center, George Mason University, Manassas, Virginia 20110, United States
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15
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Pouplana R, Campanera JM. Energetic contributions of residues to the formation of early amyloid-β oligomers. Phys Chem Chem Phys 2014; 17:2823-37. [PMID: 25503571 DOI: 10.1039/c4cp04544k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Low-weight amyloid-β (Aβ) oligomers formed at early stages of oligomerization rather than fibril assemblies seem to be the toxic components that drive neurodegeneration in Alzheimer's disease. Unfortunately, detailed knowledge of the structure of these early oligomers at the residue level is not yet available. In this study, we performed all-atom explicit solvent molecular dynamics simulations to examine the oligomerization process of Aβ10-35 monomers when forming dimers, trimers, tetramers and octamers, with four independent simulations of a total simulated time of 3 μs for each oligomer system. The decomposition of the stability free energy by MM-GBSA methodology allowed us to unravel the network of energetic interactions that stabilize such oligomers. The contribution of the intermonomeric van der Waals term is the most significant energy feature of the oligomerization process, consistent with the so-called hydrophobic effect. Furthermore, the decomposition of the stability free energy into residues and residue-pairwise terms revealed that it is mainly apolar interactions between the three specific hydrophobic fragments 31-35 (C-terminal region), 17-20 (central hydrophobic core) and 12-14 (N-terminal region) that are responsible for such a favourable effect. The conformation in which the hydrophobic cthr-chc interaction is oriented perpendicularly is particularly important. We propose three other model substructures that favour the oligomerization process and can thus be considered as molecular targets for future inhibitors. Understanding Aβ oligomerization at the residue level could lead to more efficient design of inhibitors of this process.
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Affiliation(s)
- R Pouplana
- Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII, s/n, Diagonal Sud, 08028, Barcelona, Catalonia, Spain.
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16
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Lockhart C, Klimov DK. Revealing Hidden Helix Propensity in Aβ Peptides by Molecular Dynamics Simulations. J Phys Chem B 2013; 117:12030-8. [DOI: 10.1021/jp407705j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Christopher Lockhart
- School
of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School
of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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17
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Powell LR, Dukes KD, Lammi RK. Probing the efficacy of peptide-based inhibitors against acid- and zinc-promoted oligomerization of amyloid-β peptide via single-oligomer spectroscopy. Biophys Chem 2012; 160:12-9. [PMID: 21945664 PMCID: PMC3210411 DOI: 10.1016/j.bpc.2011.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/26/2011] [Accepted: 08/29/2011] [Indexed: 01/18/2023]
Abstract
One avenue for prevention and treatment of Alzheimer's disease involves inhibiting the aggregation of amyloid-β peptide (Aβ). Given the deleterious effects reported for Aβ dimers and trimers, it is important to investigate inhibition of the earliest association steps. We have employed quantized photobleaching of dye-labeled Aβ peptides to characterize four peptide-based inhibitors of fibrillogenesis and/or cytotoxicity, assessing their ability to inhibit association in the smallest oligomers (n=2-5). Inhibitors were tested at acidic pH and in the presence of zinc, conditions that may promote oligomerization in vivo. Distributions of peptide species were constructed by examining dozens of surface-tethered monomers and oligomers, one at a time. Results show that all four inhibitors shift the distribution of Aβ species toward monomers; however, efficacies vary for each compound and sample environment. Collectively, these studies highlight promising design strategies for future oligomerization inhibitors, affording insight into oligomer structures and inhibition mechanisms in two physiologically significant environments.
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Affiliation(s)
- Lyndsey R Powell
- Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, SC 29733, USA
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18
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Dong H, Hao C, Chen J, Qiu J. Time-dependent density functional theory study on the hydrogen bonding in electronic excited states of 6-amino-3-((thiophen-2-yl) methylene)-phthalide in methanol solution. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2011.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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19
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Velez-Vega C, Escobedo FA. Characterizing the structural behavior of selected Aβ-42 monomers with different solubilities. J Phys Chem B 2011; 115:4900-10. [PMID: 21486050 DOI: 10.1021/jp1086575] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The conformational behavior of the wild-type amyloid β-42 (Aβ-42) monomer and two of its mutants was explored via all-atom replica exchange molecular dynamics simulations in explicit solvent, to identify structural features that may promote or deter early-stage oligomerization. The markers used for this purpose indicate that while the three peptides are relatively flexible they have distinct preferential structures and degree of rigidity. In particular, we found that one mutant that remains in the monomeric state in experiments displays a characteristic N-terminal structure that significantly enhances its rigidity. This finding is consistent with various studies that have detected a reduction in oligomerization frequency and Aβ-related toxicity upon sequence-specific antibody or ligand binding to the N-terminal tail of wild-type monomers, likely leading to the stabilization of this region. In general, our results highlight a potential role of the N-terminal segment on Aβ oligomerization and give insights into specific interactions that may be responsible for promoting the pronounced structural changes observed upon introducing point mutations on the wild-type Aβ-42 peptide.
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Affiliation(s)
- Camilo Velez-Vega
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
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20
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Wu C, Shea JE. Coarse-grained models for protein aggregation. Curr Opin Struct Biol 2011; 21:209-20. [DOI: 10.1016/j.sbi.2011.02.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 02/03/2011] [Accepted: 02/07/2011] [Indexed: 01/09/2023]
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21
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Davis CH, Berkowitz ML. A molecular dynamics study of the early stages of amyloid-beta(1-42) oligomerization: the role of lipid membranes. Proteins 2010; 78:2533-45. [PMID: 20602359 DOI: 10.1002/prot.22763] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
As research progresses toward understanding the role of the amyloid-beta (Abeta) peptide in Alzheimer's disease, certain aspects of the aggregation process for Abeta are still not clear. In particular, the accepted constitution of toxic aggregates in neurons has shifted toward small oligomers. However, the process of forming these oligomers in cells is also not full clear. Even more interestingly, it has been implied that cell membranes, and, in particular, anionic lipids within those membranes, play a key role in the progression of Abeta aggregation, but the exact nature of the Abeta-membrane interaction in this process is unknown. In this work, we use a thermodynamic cycle and umbrella sampling molecular dynamics to investigate dimerization of the 42-residue Abeta peptide on model zwitterionic dipalmitoylphosphatidylcholine (DPPC) or model anionic dioleoylphosphatidylserine (DOPS) bilayer surfaces. We determined that Abeta dimerization was strongly favored through interactions with the DOPS bilayer. Further, our calculations showed that the DOPS bilayer promoted strong protein-protein interactions within the Abeta dimer, whereas DPPC favored strong protein-lipid interactions. By promoting dimer formation and subsequent dimer release into the solvent, the DOPS bilayer acts as a catalyst in Abeta aggregation.
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Affiliation(s)
- Charles H Davis
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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22
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Nikolic A, Baud S, Rauscher S, Pomès R. Molecular mechanism of β-sheet self-organization at water-hydrophobic interfaces. Proteins 2010; 79:1-22. [DOI: 10.1002/prot.22854] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 07/21/2010] [Accepted: 07/24/2010] [Indexed: 12/20/2022]
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23
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Miller Y, Ma B, Nussinov R. Polymorphism in Alzheimer Abeta amyloid organization reflects conformational selection in a rugged energy landscape. Chem Rev 2010; 110:4820-38. [PMID: 20402519 PMCID: PMC2920034 DOI: 10.1021/cr900377t] [Citation(s) in RCA: 234] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Indexed: 01/13/2023]
Affiliation(s)
| | | | - Ruth Nussinov
- To whom correspondence should be addressed. Tel.: (301) 846-5579. Fax: (301) 846-5598. E-mail:
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24
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Horn AHC, Sticht H. Amyloid-beta42 oligomer structures from fibrils: a systematic molecular dynamics study. J Phys Chem B 2010; 114:2219-26. [PMID: 20104925 DOI: 10.1021/jp100023q] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Recent experimental data demonstrate that small, soluble amyloid-beta42 oligomers play an important role in Alzheimer's disease because they exhibit neurotoxic properties and also act as seed for fibril growth. We performed all-atom molecular dynamics simulations in explicit solvent of 0.7 micros in total on five Abeta9-42 oligomers (monomer through pentamer) starting from the fibril conformation. The initial conformation proves to be stable in the trimer to pentamer, and the two parallel in-register beta-sheets as well as the connecting turn are preserved. The dimer undergoes larger conformational changes in its C-terminus, and the predominant conformation detected exhibits an additional antiparallel beta-sheet in one of the subunits. This conformational rearrangement allows efficient shielding of hydrophobic residues from the solvent, which is not possible for a dimer in the fibril conformation. In addition to the presence of the hydrogen bonds in the beta-sheets, the larger oligomers are stabilized by interchain D23-K28 salt bridges, whereas a D23-N27 interaction is found in the dimer. The degree of structural similarity to the fibril conformation detected for the oligomers in the simulation may also offer a structural explanation for the experimental finding that trimers and tetramers act as more potent seeds in fibril formation than dimers because only small conformational changes will be required for fibril growth. The fact that the dimer predominantly exists in conformations distinct from the larger oligomers and the fibril is also interesting for the design of anti-Alzheimer drugs, because it suggests that multiple drugs might be required to target the structurally different neurotoxic oligomers.
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Affiliation(s)
- Anselm H C Horn
- Bioinformatik, Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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25
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Campanera JM, Pouplana R. MMPBSA decomposition of the binding energy throughout a molecular dynamics simulation of amyloid-beta (Abeta(10-35)) aggregation. Molecules 2010; 15:2730-48. [PMID: 20428075 PMCID: PMC6257327 DOI: 10.3390/molecules15042730] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2010] [Revised: 03/11/2010] [Accepted: 03/19/2010] [Indexed: 11/16/2022] Open
Abstract
Recent experiments with amyloid-beta (Aβ) peptides indicate that the formation of toxic oligomers may be an important contribution to the onset of Alzheimer’s disease. The toxicity of Aβ oligomers depend on their structure, which is governed by assembly dynamics. However, a detailed knowledge of the structure of at the atomic level has not been achieved yet due to limitations of current experimental techniques. In this study, replica exchange molecular dynamics simulations are used to identify the expected diversity of dimer conformations of Aβ10−35 monomers. The most representative dimer conformation has been used to track the dimer formation process between both monomers. The process has been characterized by means of the evolution of the decomposition of the binding free energy, which provides an energetic profile of the interaction. Dimers undergo a process of reorganization driven basically by inter-chain hydrophobic and hydrophilic interactions and also solvation/desolvation processes.
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Affiliation(s)
| | - Ramon Pouplana
- Author to whom correspondence should be addressed; E-Mail:
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26
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Dupuis NF, Wu C, Shea JE, Bowers MT. Human islet amyloid polypeptide monomers form ordered beta-hairpins: a possible direct amyloidogenic precursor. J Am Chem Soc 2010; 131:18283-92. [PMID: 19950949 DOI: 10.1021/ja903814q] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Oligomerization of human islet amyloid polypeptide (IAPP) has been increasingly considered a pathogenic process in type II diabetes. Here structural features of the IAPP monomer have been probed using a combination of ion mobility mass spectrometry (IMS-MS) and all-atom replica exchange molecular dynamics (REMD) simulations. Three distinct conformational families of human IAPP monomer are observed in IMS experiments, and two of them are identified as dehydrated solution structures on the basis of our simulation results: one is an extended beta-hairpin structural family, and the second is a compact helix-coil structural family. The extended beta-hairpin family is topologically similar to the peptide conformation in the solid-state NMR fibril structure published by Tycko and co-workers. It is absent in both experiments and simulations performed on the non-amyloidogenic rat IAPP, suggesting it may play an important role in the fibrillation pathway of human IAPP. In addition, pH dependence studies show that the relative abundance of the beta-hairpin structural family is significantly enhanced at pH 8.0. This observation is consistent with the increased rate of fibrillation at high pH in vitro and offers a possible explanation of the pH dependent fibrillation in vivo. This paper, to the best of our knowledge, presents the first experimental evidence of a significant population of beta-hairpin conformers for the IAPP peptide. It is consistent with a previous suggestion in the literature that beta-sheet-rich oligomers are assembled from ordered beta-hairpins rather than from coiled structures.
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Affiliation(s)
- Nicholas F Dupuis
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
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27
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Tsai HHG, Lee JB, Tseng SS, Pan XA, Shih YC. Folding and membrane insertion of amyloid-beta (25-35) peptide and its mutants: Implications for aggregation and neurotoxicity. Proteins 2010; 78:1909-25. [DOI: 10.1002/prot.22705] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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28
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Davis CH, Berkowitz ML. Structure of the amyloid-beta (1-42) monomer absorbed to model phospholipid bilayers: a molecular dynamics study. J Phys Chem B 2010; 113:14480-6. [PMID: 19807060 DOI: 10.1021/jp905889z] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The amyloid-beta (Abeta) peptide, the 39 to 43 amino acid peptide that plays a substantial role in Alzheimer's disease, has been shown to interact strongly with lipids both in vitro and in vivo. Abeta-lipid interactions have been proposed as a considerable factor in accelerating Abeta aggregation through the templating role of membranes in aggregation disorders. Previous work has shown that anionic lipids are able to significantly increase Abeta aggregation rate and induce a structural conversion in Abeta from a random coil to a beta-structure that is similar to the monomer structure observed in mature fibrils. However, it is unclear if this structural change occurs with the Abeta monomer because of direct interactions with the lipids or if the structural change results from protein-protein interactions during oligomerization. We use extensive replica exchange molecular dynamics simulations of an Abeta monomer bound to a homogeneous model zwitterionic or anionic lipid bilayer. From these simulations, we do not observe any significant beta-structure formation except for a small, unstable beta-hairpin formed on the anionic dioleylphosphatidylserine bilayer. Further, we see that the Asp23-Lys28 salt bridge that plays a role in beta-hairpin formation is not substantially formed on the bilayer surface and that Lys28 preferentially interacts with lipids when bound to the bilayer. These results suggest that the structural conversion seen in experiments are not due to the ordering of monomeric Abeta on the bilayer surface but are a result of protein-protein interactions enhanced by Abeta binding to the cell membrane.
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Affiliation(s)
- Charles H Davis
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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29
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Yokoyama K, Gaulin NB, Cho H, Briglio NM. Temperature Dependence of Conjugation of Amyloid Beta Protein on the Surfaces of Gold Colloidal Nanoparticles. J Phys Chem A 2009; 114:1521-8. [DOI: 10.1021/jp907880f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kazushige Yokoyama
- Department of Chemistry, The State University of New York, Geneseo College, One College Circle, Geneseo, New York 14454
| | - Nicole B. Gaulin
- Department of Chemistry, The State University of New York, Geneseo College, One College Circle, Geneseo, New York 14454
| | - Hyunah Cho
- Department of Chemistry, The State University of New York, Geneseo College, One College Circle, Geneseo, New York 14454
| | - Nicole M. Briglio
- Department of Chemistry, The State University of New York, Geneseo College, One College Circle, Geneseo, New York 14454
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30
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Grabenauer M, Wu C, Soto P, Shea JE, Bowers MT. Oligomers of the Prion Protein Fragment 106−126 Are Likely Assembled from β-Hairpins in Solution, and Methionine Oxidation Inhibits Assembly without Altering the Peptide’s Monomeric Conformation. J Am Chem Soc 2009; 132:532-9. [DOI: 10.1021/ja905595k] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Megan Grabenauer
- Departments of Chemistry and Biochemistry and of Physics, University of California, Santa Barbara, California 93106, and Department of Physics, Creighton University, Omaha, Nebraska 68178
| | - Chun Wu
- Departments of Chemistry and Biochemistry and of Physics, University of California, Santa Barbara, California 93106, and Department of Physics, Creighton University, Omaha, Nebraska 68178
| | - Patricia Soto
- Departments of Chemistry and Biochemistry and of Physics, University of California, Santa Barbara, California 93106, and Department of Physics, Creighton University, Omaha, Nebraska 68178
| | - Joan-Emma Shea
- Departments of Chemistry and Biochemistry and of Physics, University of California, Santa Barbara, California 93106, and Department of Physics, Creighton University, Omaha, Nebraska 68178
| | - Michael T. Bowers
- Departments of Chemistry and Biochemistry and of Physics, University of California, Santa Barbara, California 93106, and Department of Physics, Creighton University, Omaha, Nebraska 68178
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31
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Molecular dynamics simulations of Ibuprofen binding to Abeta peptides. Biophys J 2009; 97:2070-9. [PMID: 19804739 DOI: 10.1016/j.bpj.2009.07.032] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 07/14/2009] [Accepted: 07/22/2009] [Indexed: 01/02/2023] Open
Abstract
Using replica exchange molecular dynamics simulations and the implicit solvent model we probed binding of ibuprofen to Abeta(10-40) monomers and amyloid fibrils. We found that the concave (CV) fibril edge has significantly higher binding affinity for ibuprofen than the convex edge. Furthermore, binding of ibuprofen to Abeta monomers, as compared to fibrils, results in a smaller free energy gain. The difference in binding free energies is likely to be related to the presence of the groove on the CV fibril edge, in which ibuprofen tends to accumulate. The confinement effect of the groove promotes the formation of large low-energy ibuprofen clusters, which rarely occur on the surface of Abeta monomers. These observations led us to suggest that the ibuprofen binding mechanism for Abeta fibrils is different from that for monomers. In general, ibuprofen shows a preference to bind to those regions of Abeta monomers (amino terminal) and fibrils (the CV edge) that are also the primary aggregation interfaces. Based on our findings and on available experimental data, we propose a rationale for the ibuprofen antiaggregation effect.
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32
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Takeda T, Klimov DK. Interpeptide interactions induce helix to strand structural transition in Abeta peptides. Proteins 2009; 77:1-13. [PMID: 19350616 DOI: 10.1002/prot.22406] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Replica exchange molecular dynamics and all-atom implicit solvent model are used to compute the structural propensities in Abeta monomers, dimers, and Abeta peptides bound to the edge of amyloid fibril. These systems represent, on an approximate level, different stages in Abeta aggregation. Abeta monomers are shown to form helical structure in the N-terminal (residues 13 to 21). Interpeptide interactions in Abeta dimers and, especially, in the peptides bound to the fibril induce a dramatic shift in the secondary structure, from helical states toward beta-strand conformations. The sequence region 10-23 in Abeta peptide is found to form most of interpeptide interactions upon aggregation. Simulation results are tested by comparing the chemical shifts in Abeta monomers computed from simulations and obtained experimentally. Possible implications of our simulations for designing aggregation-resistant variants of Abeta are discussed.
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Affiliation(s)
- Takako Takeda
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, Virginia 20110, USA
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33
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Chebaro Y, Mousseau N, Derreumaux P. Structures and thermodynamics of Alzheimer's amyloid-beta Abeta(16-35) monomer and dimer by replica exchange molecular dynamics simulations: implication for full-length Abeta fibrillation. J Phys Chem B 2009; 113:7668-75. [PMID: 19415895 DOI: 10.1021/jp900425e] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Many proteins display a strand-loop-strand motif in their amyloid fibrillar states. For instance, the amyloid beta-protein, Abeta1-40, associated with Alzheimer's disease, displays a loop at positions 22-28 in its amyloid fibril state. It has been suggested that this loop could appear early in the aggregation process, but quantitative information regarding its presence in small oligomers remains scant. Because residues 1-15 are disordered in Abeta1-42 fibrils and Abeta10-35 forms fibrils in vitro, we select the peptide Abeta16-35, centered on residues 22-28 and determine the structures and thermodynamics of the monomer and dimer using coarse-grained implicit solvent replica exchange molecular dynamics simulations. Our simulations totalling 5 mus for the monomer and 12 micros for the dimer show no sign of strong secondary structure signals in both instances and the significant impact of dimerization on the global structure of Abeta16-35. They reveal however that the loop 22-28 acts as a quasi-independent unit in both species. The loop structure ensemble we report in Abeta16-35 monomer and dimer has high similarity to the loop formed by the Abeta21-30 peptide in solution and, to a lesser extent, to the loop found in Abeta1-40 fibrils. We discuss the implications of our findings on the assembly of full-length Abeta.
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Affiliation(s)
- Yassmine Chebaro
- Laboratoire de Biochimie Théeorique, UPR 9080 CNRS, Institut de Biologie Physico Chimique et Université Paris Diderot-Paris 7, 13 rue Pierre et Marie Curie, 75005 Paris, France
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34
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Takeda T, Klimov DK. Side chain interactions can impede amyloid fibril growth: replica exchange simulations of Abeta peptide mutant. J Phys Chem B 2009; 113:11848-57. [PMID: 19708712 PMCID: PMC2765228 DOI: 10.1021/jp904070w] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Using replica exchange molecular dynamics, we study the effect of Asp23Tyr mutation on Abeta(10-40) fibril growth. The effect of this mutation is revealed through the computation of free energy landscapes, the distributions of peptide-fibril interactions, and by comparison with the wild-type Abeta(10-40) peptide. Asp23Tyr mutation has a relatively minor influence on the docking of Abeta peptides to the fibril. However, it has a strong impact on the locking stage due to profound stabilization of the parallel in-registry beta-sheets formed by the peptides on the fibril edge. The enhanced stability of parallel beta-sheets results from the deletion of side chain interactions formed by Asp23, which are incompatible with the fibril-like conformers. Consequently, Asp23Tyr mutation is expected to promote fibril growth. We argue that strong off-registry side chain interactions may slow down fibril assembly as it occurs for the wild-type Abeta peptide. The analysis of experimental data offers support to our in silico conclusions.
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Affiliation(s)
- Takako Takeda
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, VA 20110
| | - Dmitri K. Klimov
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, VA 20110
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35
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Reddy AS, Izmitli A, de Pablo JJ. Effect of trehalose on amyloid β (29–40)-membrane interaction. J Chem Phys 2009; 131:085101. [DOI: 10.1063/1.3193726] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Takeda T, Klimov DK. Probing energetics of Abeta fibril elongation by molecular dynamics simulations. Biophys J 2009; 96:4428-37. [PMID: 19486667 DOI: 10.1016/j.bpj.2009.03.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 02/23/2009] [Accepted: 03/03/2009] [Indexed: 11/30/2022] Open
Abstract
Using replica exchange molecular dynamics simulations and an all-atom implicit solvent model, we probed the energetics of Abeta(10-40) fibril growth. The analysis of the interactions between incoming Abeta peptides and the fibril led us to two conclusions. First, considerable variations in fibril binding propensities are observed along the Abeta sequence. The peptides in the fibril and those binding to its edge interact primarily through their N-termini. Therefore, the mutations affecting the Abeta positions 10-23 are expected to have the largest impact on fibril elongation compared with those occurring in the C-terminus and turn. Second, we performed weak perturbations of the binding free energy landscape by scanning partial deletions of side-chain interactions at various Abeta sequence positions. The results imply that strong side-chain interactions--in particular, hydrophobic contacts--impede fibril growth by favoring disordered docking of incoming peptides. Therefore, fibril elongation may be promoted by moderate reduction of Abeta hydrophobicity. The comparison with available experimental data is presented.
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Affiliation(s)
- Takako Takeda
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, Virginia, USA
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37
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Takeda T, Klimov DK. Probing the effect of amino-terminal truncation for Abeta1-40 peptides. J Phys Chem B 2009; 113:6692-702. [PMID: 19419218 DOI: 10.1021/jp9016773] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We examine the effect of deletion of the amino-terminal (residues 1-9) on the structure and energetics of Abeta1-40 peptides. To this end, we use replica exchange molecular dynamics to compare the conformational ensembles of Abeta1-40 and amino-truncated Abeta10-40 monomers and dimers. Overall, the deletion of the amino-terminal appears to cause minor structural and energetic changes in Abeta monomers and dimers. More specifically, our findings are as follows: (1) there is a small but discernible conversion of beta-strand structure into helix upon amino-terminal deletion, (2) secondary structure changes due to truncation are caused by missing side chain interactions formed by the amino-terminal, and (3) the amino-terminal together with the central sequence region (residues 10-23) represents the primary aggregation interface in Abeta1-40 dimers. The amino-truncated Abeta10-40 retains this aggregation interface, which is reduced to the central sequence region. We argue that the analysis of available experimental data supports our conclusions. Our findings also suggest that amino-truncated Abeta10-40 peptide is an adequate model for studying Abeta1-40 aggregation.
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Affiliation(s)
- Takako Takeda
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, Virginia 20110, USA
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38
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Jang S, Yuan JM, Shin J, Measey TJ, Schweitzer-Stenner R, Li FY. Energy Landscapes Associated with the Self-Aggregation of an Alanine-Based Oligopeptide (AAKA)4. J Phys Chem B 2009; 113:6054-61. [DOI: 10.1021/jp809279r] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Soonmin Jang
- Department of Chemistry, Sejong University, Seoul 143-747, Korea, Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan 402, R.O.C
| | - Jian-Min Yuan
- Department of Chemistry, Sejong University, Seoul 143-747, Korea, Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan 402, R.O.C
| | - Jungho Shin
- Department of Chemistry, Sejong University, Seoul 143-747, Korea, Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan 402, R.O.C
| | - Thomas J. Measey
- Department of Chemistry, Sejong University, Seoul 143-747, Korea, Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan 402, R.O.C
| | - Reinhard Schweitzer-Stenner
- Department of Chemistry, Sejong University, Seoul 143-747, Korea, Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan 402, R.O.C
| | - Feng-Yin Li
- Department of Chemistry, Sejong University, Seoul 143-747, Korea, Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan 402, R.O.C
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39
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Zhang A, Qi W, Good TA, Fernandez EJ. Structural differences between Abeta(1-40) intermediate oligomers and fibrils elucidated by proteolytic fragmentation and hydrogen/deuterium exchange. Biophys J 2009; 96:1091-104. [PMID: 19186145 DOI: 10.1016/j.bpj.2008.10.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 10/09/2008] [Indexed: 12/24/2022] Open
Abstract
The aggregation of amyloid-beta protein (Abeta) in vivo is a critical pathological event in Alzheimer's disease. Although more and more evidence shows that the intermediate oligomers are the primary neurotoxic species in Alzheimer's disease, the particular structural features responsible for the toxicity of these intermediates are poorly understood. We measured the peptide level solvent accessibility of multiple Abeta(1-40) aggregated states using hydrogen exchange detected by mass spectrometry. A gradual reduction in solvent accessibility, spreading from the C-terminal region to the N-terminal region was observed with ever more aggregated states of Abeta peptide. The observed hydrogen exchange protection begins with reporter peptides 20-34 and 35-40 in low molecular weight oligomers found in fresh samples and culminates with increasing solvent protection of reporter peptide 1-16 in long time aged fibrillar species. The more solvent exposed structure of intermediate oligomers in the N-termini relative to well-developed fibrils provides a novel explanation for the structure-dependent neurotoxicity of soluble oligomers reported previously.
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Affiliation(s)
- Aming Zhang
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, USA
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40
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Takeda T, Klimov DK. Replica exchange simulations of the thermodynamics of Abeta fibril growth. Biophys J 2009; 96:442-52. [PMID: 19167295 DOI: 10.1016/j.bpj.2008.10.008] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Accepted: 10/01/2008] [Indexed: 11/17/2022] Open
Abstract
Replica exchange molecular dynamics and an all-atom implicit solvent model are used to probe the thermodynamics of deposition of Alzheimer's Abeta monomers on preformed amyloid fibrils. Consistent with the experiments, two deposition stages have been identified. The docking stage occurs over a wide temperature range, starting with the formation of the first peptide-fibril interactions at 500 K. Docking is completed when a peptide fully adsorbs on the fibril edge at the temperature of 380 K. The docking transition appears to be continuous, and occurs without free energy barriers or intermediates. During docking, incoming Abeta monomer adopts a disordered structure on the fibril edge. The locking stage occurs at the temperature of approximately 360 K and is characterized by the rugged free energy landscape. Locking takes place when incoming Abeta peptide forms a parallel beta-sheet structure on the fibril edge. Because the beta-sheets formed by locked Abeta peptides are typically off-registry, the structure of the locked phase differs from the structure of the fibril interior. The study also reports that binding affinities of two distinct fibril edges with respect to incoming Abeta peptides are different. The peptides bound to the concave edge have significantly lower free energy compared to those bound on the convex edge. Comparison with the available experimental data is discussed.
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Affiliation(s)
- Takako Takeda
- Department of Bioinformatics and Computational Biology, George Mason University, Manassas, Virginia, USA
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41
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Reddy G, Straub JE, Thirumalai D. Influence of preformed Asp23-Lys28 salt bridge on the conformational fluctuations of monomers and dimers of Abeta peptides with implications for rates of fibril formation. J Phys Chem B 2009; 113:1162-72. [PMID: 19125574 PMCID: PMC3098509 DOI: 10.1021/jp808914c] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Recent experiments have shown that the congener Abeta(1-40)[D23-K28], in which the side chains of charged residues Asp23 and Lys28 are linked by a lactam bridge, forms amyloid fibrils that are structurally similar to the wild type (WT) Abeta peptide, but at a rate that is nearly 1000 times faster. We used all atom molecular dynamics simulations in explicit water, and two force fields, of the WT dimer, a monomer with the lactam bridge (Abeta(10-35)-lactam[D23-K28]), and the monomer and dimers with harmonically constrained D23-K28 salt bridge (Abeta(10-35)[D23-K28]) to understand the origin of the enhanced fibril rate formation. The simulations show that the assembly competent fibril-like monomer (N*) structure, which is present among the conformations sampled by the isolated monomer, with strand conformations in the residues spanning the N and C termini and a bend involving residues D(23) VGSNKG(29), are populated to a much greater extent in Abeta(10-35)[D23-K28] and Abeta(10-35)-lactam[D23-K28] than in the WT, which has negligible probability of forming N*. The salt bridge in N* of Abeta(10-35)[D23-K28], whose topology is similar to that found in the fibril, is hydrated. The reduction in the free energy barrier to fibril formation in Abeta(10-35)[D23-K28] and in Abeta(10-35)-lactam[D23-K28], compared to the WT, arises largely due to entropic restriction which enables the bend formation. A decrease in the entropy of the unfolded state and the lesser penalty for conformational rearrangement including the formation of the salt bridge in Abeta peptides with D23-K28 constraint results in a reduction in the kinetic barrier in the Abeta(1-40)-lactam[D23-K28] congener compared to the WT. The decrease in the barrier, which is related to the free energy cost of forming a bend, is estimated to be in the range (4-7)k(B)T. Although a number of factors determine the growth of fibrils, the decrease in the free energy barrier, relative to the WT, to N* formation is a major factor in the rate enhancement in the fibril formation of Abeta(1-40)[D23-K28] congener. Qualitatively similar results were obtained using simulations of Abeta(9-40) peptides and various constructs related to the Abeta(10-35) systems that were probed using OPLS and CHARMM force fields. We hypothesize that mutations or other constraints that preferentially enhance the population of the N* species would speed up aggregation rates. Conversely, ligands that lock it in the fibril-like N* structure would prevent amyloid formation.
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Affiliation(s)
- Govardhan Reddy
- Biophysics Program, Institute for Physical Sciences and Technology, University of Maryland, College Park, MD 20742
| | - John E. Straub
- Department of Chemistry, Boston University, Boston, MA 02215
| | - Devarajan Thirumalai
- Biophysics Program, Institute for Physical Sciences and Technology and Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
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Liang Y, Pingali SV, Jogalekar AS, Snyder JP, Thiyagarajan P, Lynn DG. Cross-Strand Pairing and Amyloid Assembly. Biochemistry 2008; 47:10018-26. [DOI: 10.1021/bi801081c] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yan Liang
- Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia 30322, and Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Sai Venkatesh Pingali
- Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia 30322, and Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Ashutosh S. Jogalekar
- Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia 30322, and Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - James P. Snyder
- Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia 30322, and Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Pappannan Thiyagarajan
- Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia 30322, and Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - David G. Lynn
- Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia 30322, and Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
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Abstract
Amyloidlike fibrils are found in many fatal diseases, including Alzheimer's disease, type II diabetes mellitus, transmissible spongiform encephalopathies, and prion diseases. These diseases are linked to proteins that have partially unfolded, misfolded, and aggregated into amyloidlike fibrils. The kinetics of amyloidlike fibrils aggregation is still hotly debated and remains an important open question. We have utilized the GNNQQNY crystal structure and high-temperature molecular dynamics simulation in explicit solvent to study the disaggregation mechanism of the GNNQQNY fibrils and to infer its likely aggregation pathways. A hexamer model and a 12-mer model both with two parallel beta-sheets separated by a dry side-chain interface were adopted in our computational analysis. A cumulative time of 1 micros was simulated for the hexamer model at five different temperatures (298 K, 348 K, 398 K, 448 K, and 498 K), and a cumulative time of 2.1 micros was simulated for the 12-mer model at four temperatures (298 K, 398 K, 448 K, and 498 K). Our disaggregation landscape and kinetics analyses indicate that tetramers probably act as the transition state in both the hexamer and the 12-mer simulations. In addition, the 12-mer simulations show that the initial aggregation nucleus is with eight peptides. Furthermore, the landscape is rather flat from 8-mers to 12-mers, indicating the absence of major barriers once the initial aggregation nucleus forms. Thus, the likely aggregation pathway is from monomers to the initial nucleus of 8-mers with tetramers as the transition state. Transition state structure analysis shows that the two dominant transition state conformations are tetramers in the 3-1 and 2-2 arrangements. The predominant nucleus conformations are in peptide arrangements maximizing dry side-chain contacts. Landscape and kinetics analyses also indicate that the parallel beta-sheets form earlier than the dry side-chain contacts during aggregation. These results provide further insights in understanding the early fibrils aggregation.
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Computational study of the binding of CuII to Alzheimer’s amyloid-β peptide: Do Aβ42 and Aβ40 bind copper in identical fashion? J Biol Inorg Chem 2008; 13:1197-204. [DOI: 10.1007/s00775-008-0403-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Accepted: 06/25/2008] [Indexed: 12/31/2022]
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