TAR DNA-binding protein 43 (TDP-43) has been identified as the major ubiquitinated aggregates in the inclusion bodies in the patients of amyotrophic lateral sclerosis (ALS) since 2006 and become a ...crucial culprit for ALS and related motor neuron diseases. Recent literature has further indicated that the major components of these aggregates are hyper-phosphorylated TDP-43 C-terminus. In an effort to clarify the conformational and physical properties of its disordered C-terminal domain, we have synthesized several peptide fragments and shown that only D1 within D1−4 can form twisted fibrils with a cross section of ∼11 nm in width under the incubation of phosphate buffer. In contrast, the D2−4 peptides all formed amorphous aggregates, showing different aggregation propensities. In addition to D1, two pathological mutant peptides, A315T and G294A, can also form fibrils that share similar shape and morphology with neuronal cytoplasmic inclusions. We propose that the residues with this region (287−322), which contains myriads of glycine repeats, may contribute significantly to the fiber formation as well as aggregation propensity. Moreover, from the conformational characterizations of D1, A315T, and G294A with EM, CD, fluorescence, and Raman spectroscopy, we found that all three peptides formed an amyloid structure, providing insights into the nature of its aggregation vis a vis the other fragments in the C-terminus of TDP-43.
TAR DNA-binding protein (TDP-43) was identified as the major ubiquitinated component deposited in the inclusion bodies in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration ...with ubiquitin-positive inclusions (FTLD-U) in 2006. Later on, numerous ALS-related mutations were found in either the glycine or glutamine/asparagine-rich region on the TDP-43 C-terminus, which hinted on the importance of mutations on the disease pathogenesis. However, how the structural conversion was influenced by the mutations and the biological significance of these peptides remains unclear. In this work, various peptides bearing pathogenic or de novo designed mutations were synthesized and displayed their ability to form twisted amyloid fibers, cause liposome leakage, and mediate cellular toxicity as confirmed by transmission electron microscopy (TEM), circular dichroism (CD), Thioflavin T (ThT) assay, Raman spectroscopy, calcein leakage assay, and cell viability assay. We have also shown that replacing glycines with prolines, known to obstruct β-sheet formation, at the different positions in these peptides may influence the amyloidogenesis process and neurotoxicity. In these cases, GGG308PPP mutant was not able to form beta-amyloid, cause liposome leakage, nor jeopardized cell survival, which hinted on the importance of the glycines (308-310) during amyloidogenesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract, and gastric adenocarcinomas are a common cancer worldwide. To differentiate GISTs from ...adenocarcinomas is important because the surgical processes for both are different; the former excises the tumor with negative margins, while the latter requires radical gastrectomy with lymph node dissection. Endoscopy with biopsy is used to distinguish GISTs from adenocarcinomas; however, it may cause tumor bleeding in GISTs. We reported here the confocal Raman microspectroscopy as an effective tool to differentiate GISTs, adenocarcinomas, and normal mucosae. Of 119 patients enrolled in this study, 102 patients underwent gastrectomy (40 GISTs and 62 adenocarcinomas), and 17 patients with benign lesions were obtained as normal mucosae. Raman signals were integrated for 100 s for each spot on the specimen, and 5 to 10 spots, depending on the sample size, were chosen for each specimen. There were significant differences among those tissues as evidenced by different Raman signal responding to phospholipids and protein structures. The spectral data were further processed and analyzed by using principal component analysis. A two-dimensional plot demonstrated that GISTs, adenocarcinomas, and normal gastric mucosae could be effectively differentiated from each other.
Gastric adenocarcinoma, a single heterogeneous disease with multiple epidemiological and histopathological characteristics, accounts for approximately 10% of cancers worldwide. It is categorized into ...four histological types: papillary adenocarcinoma (PAC), tubular adenocarcinoma (TAC), mucinous adenocarcinoma (MAC), and signet ring cell adenocarcinoma (SRC). Effective differentiation of the four types of adenocarcinoma will greatly improve the treatment of gastric adenocarcinoma to increase its five-year survival rate. We reported here the differentiation of the four histological types of gastric adenocarcinoma from the molecularly structural viewpoint of confocal Raman microspectroscopy. In total, 79 patients underwent laparoscopic or open radical gastrectomy during 2008-2011: 21 for signet ring cell carcinoma, 21 for tubular adenocarcinoma, 14 for papillary adenocarcinoma, 6 for mucinous carcinoma, and 17 for normal gastric mucosas obtained from patients underwent operation for other benign lesions. Clinical data were retrospectively reviewed from medical charts, and Raman data were processed and analyzed by using principal component analysis (PCA) and linear discriminant analysis (LDA). Two-dimensional plots of PCA and LDA clearly demonstrated that the four histological types of gastric adenocarcinoma could be differentiated, and confocal Raman microspectroscopy provides potentially a rapid and effective method for differentiating SRC and MAC from TAC or PAC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A simple and economical method to isolate whey protein from fresh raw milk is developed by serial defatting, casein eliminating, lactose removing, and separating by gel filtration chromatography. ...Four major whey components, including immunoglobulin (Ig), bovine serum albumin (BSA), β-lactoglobulin (β-Lg) and α-lactalbumin (α-Lac), and a non-protein of low molecular mass (∼1.7
kDa) but strong absorbance at 280
nm, are detected simultaneously. The small non-protein molecule is rich in aromatic amino acids and thiol groups as supported by the structural characterization with near infrared Fourier transform Raman spectroscopy (FT-Raman). FT-Raman results show that the secondary structure of Ig is dominated by anti-parallel β-pleated sheet; BSA is mainly in α-helix; both β-form and unordered structure are important in β-Lg; while α-Lac is mostly in α-helix coupling with random coil. Differences in the Raman profile for each whey component reflect their intrinsic compositional differences and distinct spatial arrangement. The S–S linkages diverging around 510–540
cm
−1 indicate that the conformation of disulfide bonds in each whey components is different, which may be responsible for their diversified behaviors in solubility, rheological and functional properties.
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► Solid-state NMR provides a sensitive tool for analyzing steroid hormone conformation. ► 17β-Estradiol reveals
singlet patterns in the
13C NMR spectra. ► 17α-Estradiol reveals
...multiplet patterns in the
13C NMR spectra. ► 17α- and 17β-estradiol are flexible to adopt different conformations in the lipid environment.
Solid-state {
1H}
13C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy has been applied to 17β-estradiol (E2) and 17α-estradiol (E2α), to analyze the steroidal ring conformations of the two isomers in the absence and presence of lipids at the atomic level. In the absence of lipid, the high-resolution
13C NMR signals of E2 in a powdered form show only
singlet patterns, suggesting a single ring conformation. In contrast, the
13C signals of E2α reveal
multiplet patterns with splittings of 20–300
Hz, implying multiple ring conformations. In the presence of a mimic of the lipid environment, made by mixing 1,2-dimyristoyl-
sn-glycero-3-phosphocholine (DMPC) and 1,2-diheptanoyl-
sn-glycero-3-phosphocholine (DHPC) in a molar ratio 3:1, E2 and E2α revealed
multiplet patterns different from those seen in the absence of lipids, indicating that the two isomers adopt multiple conformations in the lipid environment. In this work, on the basis of chemical shift isotropy and anisotropy analysis, we demonstrated that E2 and E2α prefer to adopt multiple steroidal ring conformations in the presence of a lipid environment, distinct from that observed in solution phase and powdered form.
Near-infrared Fourier transform Raman (FT-Raman) spectroscopy was employed to study the molecular structure of edible zein films/coatings, which were fabricated directly from zein protein. The ...secondary structure of zein protein was mainly in α-helix and remained unaltered during film formation as evidenced by the vibrational modes of amide I at 1656 cm-1 and amide III at 1274 cm-1. Raman results indicated that hydrophobic interaction played an important role in the formation of zein film and disulfide bonding might be responsible for the structural stability of zein protein during film formation. To enhance its antimicrobial property, an antimicrobial zein film was manufactured by incorporating zein protein with benzoic acid whose structure was then characterized by FT-Raman. It showed that physical entrapment or hydrophobic interaction was crucial to the incorporation of benzoic acid with zein protein, and the secondary structure of the antimicrobial film was still maintained in α-helical form. In addition, FT-Raman exhibits its preference in directly determining the thickness of zein films/coatings. By correlating the Raman intensity ratio of ν1003 to ν84 (I 1003/84) versus the thickness of zein film, a linear relationship with high coefficient (R 2 = 0.9927) was obtained, which was then used pragmatically to determine the thickness of zein coatings on apple. It showed that the FT-Raman result (thickness = 0.27 ± 0.01 mm) was consistent with that of classical micrometric measurement (thickness = 0.28 ± 0.02 mm). Consequently, FT-Raman provides a direct, simple, and reagent-free method to characterize the structure and the thickness of zein films/coatings. Keywords: FT-Raman; edible zein films/coatings; zein protein; antimicrobial film; film thickness
Making good use of interactions between analyte molecules and the metal nanoparticles is key to impact the detection limit in a surface-enhanced Raman scattering (SERS) based detections. SERS was ...applied to the analysis of catechin and it was found that the relative abundance of catechin in the sample to citrate-capped AgNPs and the aggregation agent NaCl plays a critical role in the quality of detection. At a component volume ratio of 6:2:1 (catechin:AgNPs:NaCl), catechin can be detected at µM levels. When the ratio is 12:2:1, Raman signals are discernible even at the attomolar concentration level (10
−18
M). Under these conditions, the SERS mechanisms and the force of laser tweezers function best. The extent of signal enhancement enabled an ultrasensitive and reproducible Raman spectroscopic determination of catechin.
Graphical abstract
At a component volume ratio of 6:2:1 (catechin:AgNPs:NaCl), catechin was detected at 10
−3
M to 10
−6
M. When the ratio was 12:2:1, the discernible concentration of catechin was found to reach the attomolar level (10
−18
M).
Display omitted
► Solid-state NMR provides a sensitive tool for analyzing steroid hormone conformation. ► DHEA and spironolactone reveal
multiplet pattern in
13C NMR spectra. ► DHEA and ...spironolactone undergo a conformational change in lipids. ► DHEA and spironolactone are flexible and can adopt slightly different conformations.
Solid-state
1H/
13C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy has been applied to two steroid compounds: dehydroepiandrosterone (DHEA) and spironolactone (SPI), to analyze their conformations at the atomic level. In the absence of lipid, the high-resolution
13C CP/MAS NMR signals of DHEA and SPI in a powder form reveal multiple patterns, with splittings of 30–160
Hz, indicating the existence of multiple conformations. In the mimic lipid environment formed by mixing 1,2-dimyristoyl-
sn-glycero-3-phosphocholine (DMPC) and 1,2-diheptanoyl-
sn-glycero-3-phosphocholine (DHPC) in a molar ratio 3:1, the resulting DHEA and SPI spectra revealed mostly
singlet patterns, suggesting that these steroids undergo a conformational change leading to a specific conformation in the lipid environment. Evidence from chemical shift isotropy and anisotropy analysis indicates that DHEA might adopt conformations subtly different from that seen in solution and in the powder form. In conclusion, we demonstrate by solid-state NMR that the structures of DHEA and SPI may adopt slightly different conformations in different chemical environments.
Recycling of materials is one way to achieve resource conservation, which could be implemented in new technology to sustain its development. We organize this review to raise awareness of the ...applications of photoluminescent carbon nanodots (C-dots) to food safety, with an emphasis on C-dots synthesized from food or food wastes. The diverse chemical constituents in agriculture and food products, including wastes, provide a multitude of carbon precursors for C-dots. Some of these C-dots have been developed to function as sensors for food-borne pathogens, heavy metals, and harmful colorants in food products. This process of using food and its byproducts to improve food safety is one step forward in the way of conservation and industry self-efficiency.
•Carbon nanodots made from recycled materials using green synthesis methods are eco-friendly.•Food and agriculture products, including wastes, make up a diverse base of starting materials for carbon nanodots.•Food-derived C-dots can be used for sensing of pathogens, heavy metals, and food colorants to improve food safety.•Waste recycling, green chemistry, and self-serving strategies altogether make the development of C-dots more sustainable.
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