Insight into the internal structure of amyloid-β oligomers by isotope-edited Fourier transform infrared spectroscopy

Baronio, Cesare M.; Baldassarre, Maurizio; Barth, Andreas

doi:10.1039/c9cp00717b

Cited by 27 publications

(20 citation statements)

References 81 publications

(127 reference statements)

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“…The maximum at 1,603 cm −1 in mixtures of labeled A and B is attributed to vibrational coupling between 13 C atoms in neighboring hydrogen-bonded β-strands, whereas the higher-frequency maximum at 1,610 cm −1 in mixtures of labeled and unlabeled peptides is likely due to the presence of 13 C-labeled strands with interspersed 12 C strands. The latter would only occur if unlabeled A is coassembled with labeled B, or vice versa, as has been reported recently for mixtures of 12 C/ 13 C-labeled amyloid-β (27). Collectively, these experimental results validate the computational observations that A and B coassemble into two-component β-sheet structures rather than self-sort.…”

supporting

confidence: 87%

Anatomy of a selectively coassembled β-sheet peptide nanofiber

Shao

Wong

Seroski

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Peptide self-assembly, wherein molecule A associates with other A molecules to form fibrillar β-sheet structures, is common in nature and widely used to fabricate synthetic biomaterials. Selective coassembly of peptide pairs A and B with complementary partial charges is gaining interest due to its potential for expanding the form and function of biomaterials that can be realized. It has been hypothesized that charge-complementary peptides organize into alternating ABAB-type arrangements within assembled β-sheets, but no direct molecular-level evidence exists to support this interpretation. We report a computational and experimental approach to characterize molecular-level organization of the established peptide pair, CATCH. Discontinuous molecular dynamics simulations predict that CATCH(+) and CATCH(−) peptides coassemble but do not self-assemble. Two-layer β-sheet amyloid structures predominate, but off-pathway β-barrel oligomers are also predicted. At low concentration, transmission electron microscopy and dynamic light scattering identified nonfibrillar ∼20-nm oligomers, while at high concentrations elongated fibers predominated. Thioflavin T fluorimetry estimates rapid and near-stoichiometric coassembly of CATCH(+) and CATCH(−) at concentrations ≥100 μM. Natural abundance13C NMR and isotope-edited Fourier transform infrared spectroscopy indicate that CATCH(+) and CATCH(−) coassemble into two-component nanofibers instead of self-sorting. However,13C–13C dipolar recoupling solid-state NMR measurements also identify nonnegligible AA and BB interactions among a majority of AB pairs. Collectively, these results demonstrate that strictly alternating arrangements of β-strands predominate in coassembled CATCH structures, but deviations from perfect alternation occur. Off-pathway β-barrel oligomers are also suggested to occur in coassembled β-strand peptide systems.

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supporting

confidence: 87%

Anatomy of a selectively coassembled β-sheet peptide nanofiber

Shao

Wong

Seroski

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…IR spectroscopy is widely used for studying the biological objects, especially for the conformational analysis of proteins [3,4,5,6,7,8]. So far, it is widely accepted that the protein-peptide group has nine characteristic absorption bands: amide A (~3300 cm −1 ), amide B (~3100 cm −1 ), amide I (~1650 cm −1 ), amide II (~1550 cm −1 ), amide III (~1300 cm −1 ), amide IV (~735 cm −1 ), amide V (~635 cm −1 ), amide VI (~600 cm −1 ), and amide VII (~200 cm −1 ) [8,9].…”

Section: Introductionmentioning

confidence: 99%

Systematic FTIR Spectroscopy Study of the Secondary Structure Changes in Human Serum Albumin under Various Denaturation Conditions

et al. 2019

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Human serum albumin (HSA) is the most abundant protein in blood plasma. HSA is involved in the transport of hormones, fatty acids, and some other compounds, maintenance of blood pH, osmotic pressure, and many other functions. Although this protein is well studied, data about its conformational changes upon different denaturation factors are fragmentary and sometimes contradictory. This is especially true for FTIR spectroscopy data interpretation. Here, the effect of various denaturing agents on the structural state of HSA by using FTIR spectroscopy in the aqueous solutions was systematically studied. Our data suggest that the second derivative deconvolution method provides the most consistent interpretation of the obtained IR spectra. The secondary structure changes of HSA were studied depending on the concentration of the denaturing agent during acid, alkaline, and thermal denaturation. In general, the denaturation of HSA in different conditions is accompanied by a decrease in α-helical conformation and an increase in random coil conformation and the intermolecular β-strands. Meantime, some variation in the conformational changes depending on the type of the denaturation agent were also observed. The increase of β-structural conformation suggests that HSA may form amyloid-like aggregates upon the denaturation.

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“…Mapping confirms that the band arises from molecules located within the cell itself or on the cell surface, and An Amide I band in the proximity of 1620-1630 cm −1 is often assigned to proteins in the amyloid fold, with a β-sheet structure supported by extended intermolecular hydrogen bonding. This fold is characterized by a two-component Amide I band, with a stronger component around 1620-1630 cm −1 and a weaker one around 1660-1690 cm −1 [22]. In the 2DCOS Synchronous plot of Figure 3A, we could not see correlation peaks involving a band in this position, suggesting that this is not a protein in the amyloid fold.…”

Section: Resultsmentioning

confidence: 82%

Infrared and 2-Dimensional Correlation Spectroscopy Study of the Effect of CH3NH3PbI3 and CH3NH3SnI3 Photovoltaic Perovskites on Eukaryotic Cells

et al. 2020

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We studied the effect of the exposure of human A549 and SH-SY5Y cell lines to aqueous solutions of organic/inorganic halide perovskites CH3NH3PbI3 (MAPbI3) and CH3NH3SnI3 (MASnI3) at the molecular level by using Fourier transform infrared microspectroscopy. We monitored the infrared spectra of some cells over a few days following exposure to the metals and observed the spectroscopic changes dominated by the appearance of a strong band at 1627 cm−1. We used Infrared (IR) mapping to show that this change was associated with the cell itself or the cellular membrane. It is unclear whether the appearance of the 1627 cm−1 band and heavy metal exposure are related by a direct causal relationship. The spectroscopic response of exposure to MAPbI3 and MASnI3 was similar, indicating that it may arise from a general cellular response to stressful environmental conditions. We used 2D correlation spectroscopy (2DCOS) analysis to interpret spectroscopic changes. In a novel application of the method, we demonstrated the viability of 2DCOS for band assignment in spatially resolved spectra. We assigned the 1627 cm−1 band to the accumulation of an abundant amide or amine containing compound, while ruling out other hypotheses. We propose a few tentative assignments to specific biomolecules or classes of biomolecules, although additional biochemical characterization will be necessary to confirm such assignments.

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Insight into the internal structure of amyloid-β oligomers by isotope-edited Fourier transform infrared spectroscopy

Abstract: Isotope-edited infrared spectroscopy reveals the structural unit of amyloid-β oligomers.

Cited by 27 publications

References 81 publications

Anatomy of a selectively coassembled β-sheet peptide nanofiber

Anatomy of a selectively coassembled β-sheet peptide nanofiber

Systematic FTIR Spectroscopy Study of the Secondary Structure Changes in Human Serum Albumin under Various Denaturation Conditions

Infrared and 2-Dimensional Correlation Spectroscopy Study of the Effect of CH3NH3PbI3 and CH3NH3SnI3 Photovoltaic Perovskites on Eukaryotic Cells

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