Effect of curcumin on amyloidogenic property of molten globule-like intermediate state of 2,5-diketo-d-gluconate reductase A

2009 ◽  
Vol 390 (10) ◽  
Author(s):  
Nandini Sarkar ◽  
Abhay Narain Singh ◽  
Vikash Kumar Dubey
Keyword(s):  
Protein Concentration ◽  
Molten Globule ◽  
Molar Ratio ◽  
Amyloid Formation ◽  
Molten Globule State ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sheet Structure ◽  
Amyloid Diseases ◽  
Β Sheet

Abstract We identified a molten globule-like intermediate of 2,5-diketo-d-gluconate reductase A (DKGR) at pH 2.5, which has a prominent β-sheet structure. The molten globule state of the protein shows amyloidogenic property >50 μm protein concentration. Interestingly, a 1:1 molar ratio of curcumin prevents amyloid formation as shown by the Thioflavin-T assay and atomic force microscopy. To the best of our knowledge, this is the first report on amyloid formation by an (α/β)8-barrel protein. The results presented here indicate that the molten globule state has an important role in amyloid formation and potential application of curcumin in protein biotechnology as well as therapeutics against amyloid diseases.

Dynamic Self-Assembly Process of a Designed Peptide

2013 ◽  
Vol 750-752 ◽  
pp. 1630-1634
Author(s):  
Li Ping Ruan ◽  
Zhi Hua Xing
Keyword(s):  
Atomic Force Microscopy ◽  
Self Assembly ◽  
The Self ◽  
Layer By Layer ◽  
Assembly Process ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sheet Structure ◽  
Β Sheet ◽  
Layer Assembly

In this paper, we reported the dynamic self-assembly process of an half-sequence ionic self-complementarity peptide CH3CO-Pro-Ser-Phe-Cys-Phe-Lys-Phe-Glu-Pro-NH2, which could self-assemble into stable nanofibers and formed hydrogel consisting of >99% water. The dynamic self-assembly process was detected by circular dichroism (CD) and atomic force microscopy (AFM). CD spectrum revealed that the mainly contents of the peptide were regular β-sheet structure. The data indicated that though the secondary structure of the peptide formed immediately, the microstructure of the self-assembly process of the designed peptide formed slowly. AFM image illustrated that the self-assembly process was layer-by-layer assembly.

scholarly journals Valorization of Apple Peels through the Study of the Effects on the Amyloid Aggregation Process of κ-Casein

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2371
Author(s):  
Valeria Guarrasi ◽  
Giacoma Cinzia Rappa ◽  
Maria Assunta Costa ◽  
Fabio Librizzi ◽  
Marco Raimondo ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Environmental Sustainability ◽  
Bovine Milk ◽  
Amyloid Formation ◽  
Aggregation Process ◽  
Amyloid Aggregation ◽  
Social Challenges ◽  
Force Microscopy ◽  
Atomic Force ◽  
Apple Peels

Waste valorization represents one of the main social challenges when promoting a circular economy and environmental sustainability. Here, we evaluated the effect of the polyphenols extracted from apple peels, normally disposed of as waste, on the amyloid aggregation process of κ-casein from bovine milk, a well-used amyloidogenic model system. The effect of the apple peel extract on protein aggregation was examined using a thioflavin T fluorescence assay, Congo red binding assay, circular dichroism, light scattering, and atomic force microscopy. We found that the phenolic extract from the peel of apples of the cultivar “Fuji”, cultivated in Sicily (Caltavuturo, Italy), inhibited κ-casein fibril formation in a dose-dependent way. In particular, we found that the extract significantly reduced the protein aggregation rate and inhibited the secondary structure reorganization that accompanies κ-casein amyloid formation. Protein-aggregated species resulting from the incubation of κ-casein in the presence of polyphenols under amyloid aggregation conditions were reduced in number and different in morphology.

scholarly journals Microbubbles Decorated with Dendronized Magnetic Nanoparticles for Biomedical Imaging. Effective Stabilization via Fluorous Interactions

2019 ◽  
Author(s):  
Da Shi ◽  
Justine Wallyn ◽  
Dinh-Vu Nguyen ◽  
Francis Perton ◽  
Delphine Felder-Flesch ◽  
...  
Keyword(s):  
Molar Ratio ◽  
Aqueous Dispersions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Investigation ◽  
End Groups ◽  
Mixed Films ◽  
Effective Stabilization ◽  
Effective Result ◽  
End Group

Dendrons fitted with three oligoethylene glycol (OEG) chains, one of which carrying a fluorinated or hydrogenated end group, and bearing a bisphosphonate polar head (C n X2 n +1OEG8Den, X = F or H; n= 2 or 4) were synthesized and grafted on the surface of iron oxide nanoparticles (IONPs) for microbubble-mediated imaging and therapeutic purposes. The size and stability of the dendronized IONPs (IONP@C n X2 n +1OEG8Den) in aqueous dispersions were monitored by dynamic light scattering. Investigation of the spontaneous adsorption of IONP@C n X2 n +1OEG8Den at the interface between air - or air saturated with perfluorohexane - and an aqueous phase establishes that exposure to the fluorocarbon gas markedly increases the rate of adsorption of the dendronized IONPs to the gas/water interface and decreases the equilibrium interfacial tension. This suggests that fluorous interactions are at play between the supernatant fluorocarbon gas and the fluorinated end groups of the dendrons. Furthermore, small, stable perfluorohexane-stabilized microbubbles (MBs) with a dipalmitoylphosphatidylcholine (DPPC) shell that incorporates IONP@C n X2 n +1OEG8Den (DPPC/Fe molar ratio 28:1) were prepared and characterized using both optical microscopy and an acoustical method of size determination. The dendrons fitted with fluorinated end groups lead to smaller and more stable MBs than those fitted with hydrogenated groups. The most effective result is already obtained with C2F5, for which MBs, ~1.0mm in radius, reach a half-life of ~6.0 h. An atomic force microscopy investigation of spin-coated mixed films of DPPC/IONP@C2X5OEG8Den combinations (molar ratio 28:1) shows that the IONPs grafted with the fluorinated dendrons are located within the phospholipid film, while those grafted with the hydrocarbon dendrons are completely absent from the phospholipid film.

scholarly journals Gels of Amyloid Fibers

Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 210 ◽  
Author(s):  
Ruizhi Wang ◽  
Xiaojing Yang ◽  
Lingwen Cui ◽  
Hang Yin ◽  
Shaohua Xu
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Atomic Force Microscopy ◽  
Melting Point ◽  
Protein Concentration ◽  
Size Exclusion ◽  
Amyloid Fibers ◽  
Force Microscopy ◽  
Atomic Force ◽  
3D Network

Protein self-assembly and formation of amyloid fibers is an early event of numerous human diseases. Continuous aggregation of amyloid fibers in vitro produces biogels, which led us to suspect that amyloid plaques and neurofibrillary tangles in Alzheimer’s disease are of biogels in nature. We applied atomic force microscopy, size exclusion chromatography, and differential scanning calorimetry to elucidate the gel’s structure, kinetics of gel formation, and melting point. We found that (1) lysozyme gelation occurs when the protein concentration is above 5 mg/mL; (2) nonfibrous protein concentration decreases and plateaus after three days of gel synthesis reaction; (3) colloidal lysozyme aggregates are detectable by both atomic force microscopy (AFM) and fast protein liquid chromatography (FPLC); (4) the gels are a three-dimensional (3D) network crosslinked by fibers coiling around each other; (5) the gels have a high melting point at around around 110 °C, which is weakly dependent on protein concentration; (6) the gels are conductive under an electric field, and (7) they form faster in the presence than in the absence of salt in the reaction buffer. The potential role of the gels formed by amyloid fibers in amyloidosis, particularly in Alzheimer’s disease was thoroughly discussed, as gels with increased viscosity, are known to restrict bulk flow and then circulation of ions and molecules.

Corrosion inhibition behavior of four benzimidazole derivatives and benzotriazole on copper surface

2020 ◽  
Vol 67 (6) ◽  
pp. 565-574
Author(s):  
Lin Liu ◽  
Shuang Lu ◽  
Ya Qi Wu ◽  
Jin Yin Xie ◽  
Jinjuan Xing
Keyword(s):  
Electrochemical Measurement ◽  
Copper Surface ◽  
Molar Ratio ◽  
Benzimidazole Derivatives ◽  
Content Type ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Mixture Concentration ◽  
Contact Angle Measurements

Purpose This paper aims to reduce environment pollution caused by benzotriazole. The authors chose one of the best inhibitors from 2-aminobenzimidazole, 2-methylbenzimidazol, 2-mercaptobenzimidazole and benzimidazole in combination with benzotriazole. Design/methodology/approach The electrochemical measurement indicated that 2-methylbenzimidazol had the best inhibition behavior. Then, it was mixed with benzotriazole. Techniques such as field emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy and optical contact angle measurements were used. Findings The results showed that the inhibition efficiency was up to 99.98%, when the mixture concentration was 20 mmol/L and the molar ratio 1:1. Originality/value 1-benzotriazole was mixed with 2-methylbenzimidazol for the first time. During the exist of methyl, 2-methylbenzimidazol has the better inhibition; this point was ignored by researchers. Graphical abstract

scholarly journals Characterization by Nano-Infrared Spectroscopy of Individual Aggregated Species of Amyloid Proteins

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2899 ◽  
Author(s):  
Jehan Waeytens ◽  
Vincent Van Hemelryck ◽  
Ariane Deniset-Besseau ◽  
Jean-Marie Ruysschaert ◽  
Alexandre Dazzi ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Spatial Resolution ◽  
Amyloid Fibrils ◽  
Thin Layers ◽  
Fibrillar Structure ◽  
Native Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Innovative Tool ◽  
Β Sheet

Amyloid fibrils are composed of aggregated peptides or proteins in a fibrillar structure with a higher β-sheet content than in their native structure. To characterize them, we used an innovative tool that coupled infrared spectroscopy with atomic force microscopy (AFM-IR). With this method, we show that we can detect different individual aggregated species from oligomers to fibrils and study their morphologies by AFM and their secondary structures based on their IR spectra. AFM-IR overcomes the weak spatial resolution of usual infrared spectroscopy and achieves a resolution of ten nanometers, the size of isolated fibrils. We characterized oligomers, amyloid fibrils of Aβ42 and fibrils of α-synuclein. To our surprise, we figured out that the nature of some surfaces (ZnSe) used to study the samples induces destructuring of amyloid samples, leading to amorphous aggregates. We strongly suggest taking this into consideration in future experiments with amyloid fibrils. More importantly, we demonstrate the advantages of AFM-IR, with a high spatial resolution (≤ 10 nm) allowing spectrum recording on individual aggregated supramolecular entities selected thanks to the AFM images or on thin layers of proteins.

Laser Raman Spectroscopic Study Of The β-Sheet Structure Of Fibrinx

1981 ◽  
Author(s):  
J Marx ◽  
G Hudry-Clergeon ◽  
L Bernard
Keyword(s):  
Protein Conformation ◽  
Protein Concentration ◽  
Structural Changes ◽  
Fibre Diameter ◽  
Enzymatic Conversion ◽  
Raman Spectroscopic ◽  
Laser Raman ◽  
Sheet Structure ◽  
Two Parameters ◽  
Β Sheet

Raman spectroscopy has proved to be a useful tool in the study of protein conformation in aqueous solution. Structural changes have been observed by this technique during the enzymatic conversion of fibrinogen into fibrin (J. Marx and col. (1979) Biochim. Biophys. Acta., 578, 107-115), particularly by the study of the Amide I and Amide III regions an important increase in the β-sheet form has been shown to occur. This variation is investigated under various conditions of ionic strength (μ) and protein concentration (c), two parameters which are known to change the fibre diameter (low values of μ and c favor an increase in the fibre diameter). The amount of β-sheet structure in fibrinogen is approximately 10 % and is unaffected by μ or c. In fibrin, the amount of β-sheet increases progressively from 20 % in fine clots (low diameter fibres) to more than 30 % in coarse clots (high diameter fibres). This correlation between the percentage of β-sheet structure and fibre diameter in fibrin indicates that numerous intermonomer hydrogen bonds are formed in the equatorial direction of the fibre. These bonds would greatly consolidate the association between monomers which is probably initiated at a few highly specific sites.

Tunable Organogelator from Alkyl-Polypeptide Diblock Prepared by Ring-Opening Polymerization

2014 ◽  
Vol 67 (1) ◽  
pp. 59 ◽  
Author(s):  
Chongyi Chen ◽  
Decheng Wu ◽  
Wenxin Fu ◽  
Zhibo Li
Keyword(s):  
Atomic Force Microscopy ◽  
Organic Solvents ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Low Concentration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Circular Dichroïsm ◽  
Β Sheet

Three alkyl-polypeptide hybrid amphiphiles were synthesized by the ring-opening polymerization (ROP) of γ-(2-methoxyethoxy)esteryl-l-glutamate N-carboxyanhydride (l-EG1Glu NCA) using alkylamine, i.e. C6H13NH2, C14H29NH2, and C16H33NH2, as initiators. As-prepared alkyl-poly-l-EG1Glu hybrids were found to form clear organogels in several organic solvents at low concentration. FTIR and circular dichroism characterizations suggested that poly-l-EG1Glu formed a predominantly β-sheet conformation, which accounted for the gelation. Transmission electron and atomic force microscopy characterizations revealed that these copolymers formed nanoribbon structures in THF.

scholarly journals Effects of the Toxic Metals Arsenite and Cadmium on α-Synuclein Aggregation In Vitro and in Cells

2021 ◽  
Vol 22 (21) ◽  
pp. 11455
Author(s):  
Emma Lorentzon ◽  
Istvan Horvath ◽  
Ranjeet Kumar ◽  
Joana Isabel Rodrigues ◽  
Markus J. Tamás ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Yeast Cells ◽  
Amyloid Formation ◽  
Amyloid Fibers ◽  
Force Microscopy ◽  
Atomic Force ◽  
In Vitro Characterization ◽  
Underlying Mechanisms

Exposure to heavy metals, including arsenic and cadmium, is associated with neurodegenerative disorders such as Parkinson’s disease. However, the mechanistic details of how these metals contribute to pathogenesis are not well understood. To search for underlying mechanisms involving α-synuclein, the protein that forms amyloids in Parkinson’s disease, we here assessed the effects of arsenic and cadmium on α-synuclein amyloid formation in vitro and in Saccharomyces cerevisiae (budding yeast) cells. Atomic force microscopy experiments with acetylated human α-synuclein demonstrated that amyloid fibers formed in the presence of the metals have a different fiber pitch compared to those formed without metals. Both metal ions become incorporated into the amyloid fibers, and cadmium also accelerated the nucleation step in the amyloid formation process, likely via binding to intermediate species. Fluorescence microscopy analyses of yeast cells expressing fluorescently tagged α-synuclein demonstrated that arsenic and cadmium affected the distribution of α-synuclein aggregates within the cells, reduced aggregate clearance, and aggravated α-synuclein toxicity. Taken together, our in vitro data demonstrate that interactions between these two metals and α-synuclein modulate the resulting amyloid fiber structures, which, in turn, might relate to the observed effects in the yeast cells. Whilst our study advances our understanding of how these metals affect α-synuclein biophysics, further in vitro characterization as well as human cell studies are desired to fully appreciate their role in the progression of Parkinson’s disease.

Sign in / Sign up

Export Citation Format

Share Document