Trifluoroethanol Modulates Amyloid Formation by the  All α-Helical URN1 FF Domain

Marinelli, Patrizia; Castillo, Virginia Leyva; Ventura, Salvador

doi:10.3390/ijms140917830

Cited by 11 publications

(12 citation statements)

References 35 publications

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“…Reducing the concentration of this co-solvent prevents this effect e.g. as shown for Aβ(1–40) [ 41 ], human carbonic anhydrase II [ 42 ], FF domain of URN1 splicing factor [ 43 ], transferrin [ 44 ], α-synuclein [ 45 ] and conalbumin [ 46 ]. The α-helices inducing effect of TFE on pEAβ(3–40) and the shift towards β-sheets by lowering the TFE contents was analyzed by recording CD spectra in aqueous buffer in different TFE concentrations.…”

Section: Resultsmentioning

confidence: 99%

Structural Analysis and Aggregation Propensity of Pyroglutamate Aβ(3-40) in Aqueous Trifluoroethanol

et al. 2015

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A hallmark of Alzheimer’s disease (AD) is the accumulation of extracellular amyloid-β (Aβ) plaques in the brains of patients. N-terminally truncated pyroglutamate-modified Aβ (pEAβ) has been described as a major compound of Aβ species in senile plaques. pEAβ is more resistant to degradation, shows higher toxicity and has increased aggregation propensity and β-sheet stabilization compared to non-modified Aβ. Here we characterized recombinant pEAβ(3–40) in aqueous trifluoroethanol (TFE) solution regarding its aggregation propensity and structural changes in comparison to its non-pyroglutamate-modified variant Aβ(1–40). Secondary structure analysis by circular dichroism spectroscopy suggests that pEAβ(3–40) shows an increased tendency to form β-sheet-rich structures in 20% TFE containing solutions where Aβ(1–40) forms α-helices. Aggregation kinetics of pEAβ(3–40) in the presence of 20% TFE monitored by thioflavin-T (ThT) assay showed a typical sigmoidal aggregation in contrast to Aβ(1–40), which lacks ThT positive structures under the same conditions. Transmission electron microscopy confirms that pEAβ(3–40) aggregated to large fibrils and high molecular weight aggregates in spite of the presence of the helix stabilizing co-solvent TFE. High resolution NMR spectroscopy of recombinantly produced and uniformly isotope labeled [U-15N]-pEAβ(3–40) in TFE containing solutions indicates that the pyroglutamate formation affects significantly the N-terminal region, which in turn leads to decreased monomer stability and increased aggregation propensity.

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Section: Resultsmentioning

confidence: 99%

Structural Analysis and Aggregation Propensity of Pyroglutamate Aβ(3-40) in Aqueous Trifluoroethanol

et al. 2015

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“…The stabilization of the native folded structure of a protein through the action of chemical compounds can markedly inhibit its unfolding and increase the energy barrier of fibrillation, and can therefore serve as an effective therapeutic strategy against protein deposition diseases [10][11][12]. Recently, some authors have reported on inhibition of fibrillation as well as destabilization of preformed fibrils using polyphenols [13,14].…”

Section: Introductionmentioning

confidence: 99%

Amyloid-like Fibril Formation by Trypsin in Aqueous Ethanol. Inhibition of Fibrillation by PEG

Kotormán

Simon

Borics

et al. 2015

PPL

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Abstract:The formation of amyloid-like fibrils was studied by using the well-known serine protease trypsin as a model protein in the presence of ethanol as organic solvent. Trypsin forms amyloid-like fibrils in aqueous ethanol at pH = 7.0. The dye Congo red (CR) was used to detect the presence of amyloid-like fibrils in the samples. The binding of CR to fibrils led to an increase in absorption intensity and a red shift in the absorption band of CR. Thioflavin T (ThT) and 8-anilino-1-naphthalenesulfonic acid (ANS) binding assays were employed to characterize amyloid-like fibril formation. The ThT binding assay revealed that the protein exhibited maximum aggregation in 60% (v/v) ethanol after incubation for 24 h at 24 o C. The ANS binding results indicated that the hydrophobic residues were more exposed to the solvent in the aggregated form of the protein. The effects of polyethylene glycol (PEG) on the formation of amyloid-like fibrils was studied in vitro. The aggregation of trypsin was followed via the kinetics of aggregation, the far-UV circular dichroism (CD) and transmission electron microscopy (TEM) in the presence and absence of PEG. The CD measurements indicated that the protein aggregates have a cross-beta structure in 60% ethanol. TEM revealed that trypsin forms fibrils with a thread-like structure. The inhibitory effect of PEG on the aggregation of trypsin increased with rising PEG concentration. PEG therefore inhibits the formation of amyloid-like fibrils of trypsin in aqueous ethanol.

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“…Aβ40 and Aβ42 cDNAs were cloned into a pET28a vector [17]. The Src homology 3 (SH3) domain was cloned into a pBat4 plasmid [36, 37], Ure2p cloned into pER26 [23], and the URN1 FF domain cloned into a pETM‐30 vector [38, 39]. The resulting plasmids were transformed into E. coli BL21 (DE3) cells.…”

Section: Methodsmentioning

confidence: 99%

Observation of a Quadrupole Surface Plasmon Mode for Au Nanorods: Effects of Surface Roughness and Crystal Facets

Hong

Shuford

Park

2013

Chemistry An Asian Journal

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This paper describes how the surface roughness and synthetic methods of Au nanorods affect the optical properties that are often associated with localized surface plasmon resonances. We synthesized Au nanorods with different aspect ratios and surface roughness by using two different synthetic strategies to observe surface plasmon resonance bands. One set of nanorods was prepared in high yield by using a seed-mediated dropwise-addition method with a growth-directing surfactant in aqueous solution (Au nanorods in aqueous phase, GNRA). The other set of Au nanorods were synthesized by the electrochemical deposition of Au onto an anodized aluminum oxide (AAO) template (Au nanorods by AAO template, GNRT). The length of the nanorods was controlled by changing the total charge that was passed through the cell and their diameter was monitored by changing the diameter of the template channel. The as-prepared Au nanorods were optimized to observe a quadrupole mode, which is one of the higher-order surface plasmon bands. Our results showed differences between the optical properties of GNRA and GNRT. The roughness and crystal structure of the Au nanorods affected their optical properties. Smooth and single-crystal surface on GNRA had larger and sharper peaks than GNRT. The discrete dipole approximation (DDA) method was used to calculate the optical properties of the Au nanorods and these results were in good agreement with our experimental results.

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Trifluoroethanol Modulates Amyloid Formation by the All α-Helical URN1 FF Domain

Cited by 11 publications

References 35 publications

Structural Analysis and Aggregation Propensity of Pyroglutamate Aβ(3-40) in Aqueous Trifluoroethanol

Structural Analysis and Aggregation Propensity of Pyroglutamate Aβ(3-40) in Aqueous Trifluoroethanol

Amyloid-like Fibril Formation by Trypsin in Aqueous Ethanol. Inhibition of Fibrillation by PEG

Observation of a Quadrupole Surface Plasmon Mode for Au Nanorods: Effects of Surface Roughness and Crystal Facets

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