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891.
Amin MN Huang W Mizanur RM Wang LX 《Journal of the American Chemical Society》2011,133(36):14404-14417
A detailed understanding of the molecular mechanism of chaperone-assisted protein quality control is often hampered by the lack of well-defined homogeneous glycoprotein probes. We describe here a highly convergent chemoenzymatic synthesis of the monoglucosylated glycoforms of bovine ribonuclease (RNase) as specific ligands of lectin-like chaperones calnexin (CNX) and calreticulin (CRT) that are known to recognize the monoglucosylated high-mannose oligosaccharide component of glycoproteins in protein folding. The synthesis of a selectively modified glycoform Gal(1)Glc(1)Man(9)GlcNAc(2)-RNase was accomplished by chemical synthesis of a large N-glycan oxazoline and its subsequent enzymatic ligation to GlcNAc-RNase under the catalysis of a glycosynthase. Selective removal of the terminal galactose by a β-galactosidase gave the Glc(1)Man(9)GlcNAc(2)-RNase glycoform in excellent yield. CD spectroscopic analysis and RNA-hydrolyzing assay indicated that the synthetic RNase glycoforms maintained essentially the same global conformations and were fully active as the natural bovine ribonuclease B. SPR binding studies revealed that the Glc(1)Man(9)GlcNAc(2)-RNase had high affinity to lectin CRT, while the synthetic Man(9)GlcNAc(2)-RNase glycoform and natural RNase B did not show CRT-binding activity. These results confirmed the essential role of the glucose moiety in the chaperone molecular recognition. Interestingly, the galactose-masked glycoform Gal(1)Glc(1)Man(9)GlcNAc(2)-RNase also showed significant affinity to lectin CRT, suggesting that a galactose β-1,4-linked to the key glucose moiety does not significantly block the lectin binding. These synthetic homogeneous glycoprotein probes should be valuable for a detailed mechanistic study on how molecular chaperones work in concert to distinguish between misfolded and folded glycoproteins in the protein quality control cycle. 相似文献
892.
Ahmed Essam Ahmed Nabawy Morra Wageh Mohammed Swelm Atef El-Sayed Abou El-Azm 《Optical and Quantum Electronics》2011,42(5):285-296
We present a detailed analysis and computations of the emitted radiation spectrum for quantum dots (QDs) microcavity light-emitting
device, where the total physical thickness of the cavity spacer was kept at 254 nm which corresponds to the wavelength of
the mode number (m) = 1 resonant mode of the cavity. Our calculation gives good results for QD diameter only from 1.2 to 6.4 nm.
The computations are used to examine how the emitted radiation spectrum can be optimized by varying the position of the light-emitting
layer, the type of cathode material, the choice of hole transport layer material, and the thickness of electron transport
layer, QD layer, and hole transport layer. These studies showed that the variation of layers geometry and the position of
the light-emitting layer will optimize the output intensity and the radiation spectrum and varying the ETL and QD layer thickness
will have a more effect on the emitted spectrum than varying HTL thickness. In addition, we have examined the effect of using
different quantum dots sizes in emission layer. On the other hand, we have investigated the difference between the electroluminescence
(EL) emissions for microcavity device in comparison with the non-cavity device, and we have found that the full width at half
maximum (FWHM) of the EL is reduced from 45 nm for the QD non-cavity LED to 30 nm for the output of a resonant microcavity
device. Finally, we have investigated the compatibility between our calculation and the experimental results and found a fairly
good agreement between them. 相似文献
893.
Mohammed A. Altahan Simon J. Coles Peter N. Horton 《Phosphorus, sulfur, and silicon and the related elements》2020,195(11):952-956
Abstract[Cu(en){B6O7(OH)6}].3H2O (1) (en = 1,2-diaminoethane), obtained as a crystalline solid in low yield (31%) after prolonged standing of an aqueous solution initially containing [Cu(en)2](OH)2 and B(OH)3 (1:7 ratio), was characterized by thermal analysis (TGA/DSC), 11B NMR and IR spectroscopy, powder XRD, and single-crystal XRD studies, and magnetic susceptibility measurements. The single-crystal X-ray diffraction revealed that the oxidoborate complex is a 1D coordination polymer with the hexaborate(2-) ligand bridging two hexacoordinate Cu(II) centers, in an alternating a fac-tridentate (κ3-O) and monodentate (κ1-O) arrangement. Cu-O coordination bonds and extensive H-bonding networks promote and stabilize the self-assembly of [Cu(en){B6O7(OH)6}].3H2O from the Dynamic Combinatorial Libraries of available reactants. [Cu(en){B6O7(OH)6}].3H2O is thermally decomposed to CuB6O10 in air at 700?°C. 相似文献
894.
El Montassir Dahmane Nadia Eladlani Mohammed Rhazi 《International Journal of Polymer Analysis and Characterization》2014,19(4):342-351
The contents of the exoskeleton of Parapenaeus longirostris from Moroccan local sources were analyzed and the percentages of inorganic salt, protein, lipid, and chitin were determined. Chitin in the α form was extracted from Parapenaeus longirostris shells by 0.25 M HCl and 1 M NaOH treatment for demineralization and deproteinization, respectively. The obtained chitin was converted into the more useful soluble chitosan. The chemical structure and physico-chemical properties of chitin and chitosan were characterized using Fourier transform-infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The molecular weight (MW) of chitosan was determined by viscometric methods. The degree of acetylation (DA) of chitin and chitosan was determined by the 1H NMR technique. To the best of our knowledge this is the first report on the extraction and characterization of chitin and chitosan from Parapenaeus longirostris. 相似文献
895.
The complex of N,N-diethyl o-nitrophenoxy acetamide and POCl3 on reaction with substituted salicylaldehyde yielded 3-(o-nitrophenoxy) coumarins. These on reaction with triethylphosphite yielded hitherto unknown benzoypranobenzoxazine ring system through a novel rearrangement. 相似文献
896.
An efficient one-step procedure for the conversion of hydroxy esters into the corresponding nitrile esters using triphenylphosphine (PPh3)-diethyl azodicarboxylate (DEAD) in the presence of acetone cyanohydrin is described. 相似文献
897.
Ambuj Gupta Jaykumar Bhasarkar Mohammed Rehaan Chandan Aabid Hussain Shaik Bandaru Kiran 《Journal of Macromolecular Science: Physics》2020,59(11):713-730
AbstractThe research described here probed the thermodynamics and kinetics of Vitamin B12 release from two types of polymeric gel scaffolds for targeted drug delivery applications. The polymeric gel scaffolds were successfully prepared from sodium alginate and polyvinyl acetate (PVA) using crosslinking and casting mechanisms, respectively. Vitamin B12 was effectively blended into the polymeric gel scaffolds during their synthesis processes. The release of Vitamin B12 from the polymeric gel scaffolds was characterized by immersing the scaffolds in a brine solution at various temperatures (25?°C, 32?°C and 37?°C) and, simultaneously, the transient concentrations were measured using a UV visible spectrophotometer. The sodium alginate gel scaffolds exhibited a more rapid release of Vitamin B12 as compared to the PVA gel scaffolds. The Vitamin B12 release kinetics from the alginate and PVA scaffolds were characterized by fitting the experimental data with various diffusion kinetic models. The Vitamin B12 release from the alginate gel scaffolds followed the Peppas-Sahlin model, whereas releases from the PVA gel scaffolds were fitted to the Hopfenberg model. The diffusion coefficients for the alginate scaffolds with respect to the three temperatures were found to be 15.72?m2/s, 17.17?m2/s and 18.58?m2/s respectively whereas the diffusion coefficients for the PVA scaffolds with respect to the three temperatures were found to be 0.23?m2/s, 0.29?m2/s and 0.32?m2/s respectively. The activation energies (Ea) for the two types of polymeric scaffolds were calculated using the Stannett equation and found to be 10.38?kJ.mol?1 and 20.47?kJ.mol?1 for the alginate and PVA scaffolds, respectively, for all three temperatures. 相似文献
898.
Mohammed A. Huneif Seham M. Alqahtani Alqahtani Abdulwahab Sultan A. Almedhesh Mater H. Mahnashi Muhammad Riaz Najm Ur-Rahman Muhammad Saeed Jan Farhat Ullah Muhammad Aasim Abdul Sadiq 《Molecules (Basel, Switzerland)》2022,27(11)
Diabetes mellitus is a metabolic disorder and is a global challenge to the current medicinal chemists and pharmacologists. This research has been designed to isolate and evaluate antidiabetic bioactives from Fragaria indica. The crude extracts, semi-purified and pure bioactives have been used in all in vitro assays. The in vitro α-glucosidase, α-amylase and DPPH free radical activities have been performed on all plant samples. The initial activities showed that ethyl acetate (Fi.EtAc) was the potent fraction in all the assays. This fraction was initially semi-purified to obtain Fi.EtAc 1–3. Among the semi-purified fractions, Fi.EtAc 2 was dominant, exhibiting potent IC50 values in all the in vitro assays. Based on the potency and availability of materials, Fi.EtAc 2 was subjected to further purification to obtain compounds 1 (2,4-dichloro-6-hydroxy-3,5-dimethoxytoluene) and 2 (2-methyl-6-(4-methylphenyl)-2-hepten-4-one). The two isolated compounds were characterized by mass and NMR analyses. The compounds 1 and 2 showed excellent inhibitions against α-glucosidase (21.45 for 1 and 15.03 for 2 μg/mL), α-amylase (17.65 and 16.56 μg/mL) and DPPH free radicals (7.62 and 14.30 μg/mL). Our study provides baseline research for the antidiabetic bioactives exploration from Fragaria indica. The bioactive compounds can be evaluated in animals-based antidiabetic activity in future. 相似文献
899.
Reshma Mary Martiz Shashank M. Patil Mohammed Abdulaziz Ahmed Babalghith Mahmoud Al-Areefi Mohammed Al-Ghorbani Jayanthi Mallappa Kumar Ashwini Prasad Nagendra Prasad Mysore Nagalingaswamy Ramith Ramu 《Molecules (Basel, Switzerland)》2022,27(8)
The present study involves the integrated network pharmacology and phytoinformatics-based investigation of phytocompounds from Ocimum tenuiflorum against diabetes mellitus-linked Alzheimer’s disease. It aims to investigate the mechanism of the Ocimum tenuiflorum phytocompounds in the amelioration of diabetes mellitus-linked Alzheimer’s disease through network pharmacology, druglikeness and pharmacokinetics, molecular docking simulations, GO analysis, molecular dynamics simulations, and binding free energy analyses. A total of 14 predicted genes of the 26 orally bioactive compounds were identified. Among these 14 genes, GAPDH and AKT1 were the most significant. The network analysis revealed the AGE-RAGE signaling pathway to be a prominent pathway linked to GAPDH with 50.53% probability. Upon the molecular docking simulation with GAPDH, isoeugenol was found to possess the most significant binding affinity (−6.0 kcal/mol). The molecular dynamics simulation and binding free energy calculation results also predicted that isoeugenol forms a stable protein–ligand complex with GAPDH, where the phytocompound is predicted to chiefly use van der Waal’s binding energy (−159.277 kj/mol). On the basis of these results, it can be concluded that isoeugenol from Ocimum tenuiflorum could be taken for further in vitro and in vivo analysis, targeting GAPDH inhibition for the amelioration of diabetes mellitus-linked Alzheimer’s disease. 相似文献
900.
Chandra Kala Mohammad Asif Sadaf Jamal Gilani Syed Sarim Imam Najam Ali Khan Mohamad Taleuzzaman Ameeduzzafar Zafar Mohammed Muqtader Ahmed Sultan Alshehri Mohammed M. Ghoneim 《Molecules (Basel, Switzerland)》2022,27(9)
Isopropyl Isothiocyanate (IPI) is a poorly water-soluble drug used in different biological activities. So, the present work was designed to prepare and evaluate IPI loaded vesicles and evaluated for vesicle size, polydispersity index (PDI) and zeta potential, encapsulation efficiency, drug release, and drug permeation. The selected formulation was coated with chitosan and further assessed for the anti-platelet and anti-thrombotic activity. The prepared IPI vesicles (F3) exhibited a vesicle size of 298 nm ± 5.1, the zeta potential of −18.7 mV, encapsulation efficiency of 86.2 ± 5.3% and PDI of 0.33. The chitosan-coated IPI vesicles (F3C) exhibited an increased size of 379 ± 4.5 nm, a positive zeta potential of 23.5 ± 2.8 mV and encapsulation efficiency of 77.3 ± 4.1%. IPI chitosan vesicle (F3C) showed enhanced mucoadhesive property (2.7 folds) and intestinal permeation (~1.8-fold) higher than IPI vesicles (F3). There was a significant (p < 0.05) enhancement in size, muco-adhesion, and permeation flux achieved after coating with chitosan. The IPI chitosan vesicle (F3C) demonstrated an enhanced bleeding time of 525.33 ± 12.43 s, anti-thrombin activity of 59.72 ± 4.21, and inhibition of platelet aggregation 68.64 ± 3.99%, and anti-platelet activity of 99.47%. The results of the study suggest that IPI chitosan vesicles showed promising in vitro results, as well as improved anti-platelet and anti-thrombotic activity compared to pure IPI and IPI vesicles. 相似文献