Examination of Adsorption Orientation of Amyloidogenic Peptides Over Nano-Gold Colloidal Particle Surfaces
Open Access
- 28 October 2019
- journal article
- research article
- Published by MDPI AG in International Journal of Molecular Sciences
- Vol. 20 (21), 5354
- https://doi.org/10.3390/ijms20215354
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.Keywords
This publication has 69 references indexed in Scilit:
- Structural Intermediates during α-Synuclein Fibrillogenesis on Phospholipid VesiclesJournal of the American Chemical Society, 2012
- New evidence on α-synuclein and Tau binding to conformation and sequence specific GCFNx01 rich DNA: Relevance to neurological disordersJournal of Pharmacy and Bioallied Sciences, 2012
- Temperature Dependence of Conjugation of Amyloid Beta Protein on the Surfaces of Gold Colloidal NanoparticlesThe Journal of Physical Chemistry A, 2009
- K3 Fragment of Amyloidogenic β2-Microglobulin Forms Ion Channels: Implication for Dialysis Related AmyloidosisJournal of the American Chemical Society, 2009
- Surface-structure-regulated cell-membrane penetration by monolayer-protected nanoparticlesNature Materials, 2008
- Fibril Growth Kinetics Reveal a Region of β2-microglobulin Important for Nucleation and Elongation of AggregationJournal of Molecular Biology, 2008
- Structure and Dynamics of Micelle-bound Human α-SynucleinJournal of Biological Chemistry, 2005
- Solution structures of micelle-bound amyloid β-(1-40) and β-(1-42) peptides of Alzheimer’s diseaseJournal of Molecular Biology, 1999
- Stabilization of α-Synuclein Secondary Structure upon Binding to Synthetic MembranesJournal of Biological Chemistry, 1998
- Soluble multimeric Alzheimer β(1–40) pre-amyloid complexes in dilute solutionNeurobiology of Aging, 1995