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Exploring the Mechanism of Inhibition of Au Nanoparticles on the Aggregation of Amyloid-β(16-22) Peptides at the Atom Level by All-Atom Molecular Dynamics.

ABSTRACT: The abnormal self-assembly of the amyloid-β peptide into toxic β-rich aggregates can cause Alzheimer’s disease. Recently, it has been shown that small gold nanoparticles (AuNPs) inhibit Aβ aggregation and fibrillation by slowing down the nucleation process in experimental studies. However, the effects of AuNPs on Aβ oligomeric structures are still unclear. In this study, we investigate the conformation of Aβ(16-22) tetramers/octamers in the absence and presence of AuNPs using extensive all-atom molecular-dynamics simulations in explicit solvent. Our studies demonstrate that the addition of AuNPs into Aβ(16-22) solution prevents β-sheet formation, and the inhibition depends on the concentration of Aβ(16-22) peptides. A detailed analysis of the Aβ(16-22)/Aβ(16-22)/water/AuNPs interactions reveals that AuNPs inhibit the β-sheet formation resulting from the same physical forces: hydrophobic interactions. Overall, our computational study provides evidence that AuNPs are likely to inhibit Aβ(16-22) and full-length Aβ fibrillation. Thus, this work provides theoretical insights into the development of inorganic nanoparticles as drug candidates for treatment of AD.

SUBMITTER: Song M

PROVIDER: S-EPMC6032210 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Exploring the Mechanism of Inhibition of Au Nanoparticles on the Aggregation of Amyloid-β(16-22) Peptides at the Atom Level by All-Atom Molecular Dynamics.

Song Menghua M Sun Yunxiang Y Luo Yin Y Zhu Yanyan Y Liu Yongsheng Y Li Huiyu H

International journal of molecular sciences 20180620 6

The abnormal self-assembly of the amyloid-β peptide into toxic β-rich aggregates can cause Alzheimer’s disease. Recently, it has been shown that small gold nanoparticles (AuNPs) inhibit Aβ aggregation and fibrillation by slowing down the nucleation process in experimental studies. However, the effects of AuNPs on Aβ oligomeric structures are still unclear. In this study, we investigate the conformation of Aβ(16-22) tetramers/octamers in the absence and presence of AuNPs using extensive all-atom ...[more]

PMID: 29925792

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Project description:Molecular dynamics simulations of amyloid-β (16-22) peptide dimer in water as well as at two different experimentally studied concentrations of hydrated ionic liquids (ILs), ethylammonium mesylate (EAM), ethylammonium nitrate (EAN), and triethylammonium mesylate (TEAM), were carried out employing an umbrella sampling method. We used the average Ψ angle of the peptide backbone as the reaction coordinate to observe the conformational changes of a peptide dimer. Secondary structural element values were calculated for the peptide dimer along the reaction coordinate to see the transition of the peptide dimer between β-sheet and α-helix conformations. We observe the β-sheet conformation as the global minimum on the free energy surfaces in both EAM and EAN ILs at both the concentrations and at a low concentration of TEAM. However, we observe α-helix conformation as the global minimum at a high concentration of TEAM. Our results are in good correlation with the experimental findings. We calculated the average number of intramolecular and intermolecular hydrogen bonds of α-helix and β-sheet conformations in all solutions, and they are in correlation with the secondary structure element values. To understand the peptide-IL interactions, atom-atom radial distribution functions of cation, anion, and water around amide oxygen and hydrogen atoms were calculated. The solvent-accessible surface area of the peptide dimer was calculated to understand the exposure of the peptide towards the solvent during conformational changes. Finally, van der Waals (vdW) and Coulomb interaction energies were calculated between peptide-cation, peptide-anion, and peptide-water to understand the stability of conformations in different concentrations. We find that the TEA cation has more vdW interaction energy compared to Coulomb interaction energy with peptide in 70% (w/w) TEAM, which mimics a membrane-like environment to induce α-helix conformation rather than β-sheet conformation.

Dataset Information

Exploring the Mechanism of Inhibition of Au Nanoparticles on the Aggregation of Amyloid-β(16-22) Peptides at the Atom Level by All-Atom Molecular Dynamics.

Publications

Exploring the Mechanism of Inhibition of Au Nanoparticles on the Aggregation of Amyloid-β(16-22) Peptides at the Atom Level by All-Atom Molecular Dynamics.

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