Site-specific incorporation of glycosylated serine and tyrosine derivatives into proteins

Glycosylation of proteins can have a dramatic effect on their physical, chemical, and biological properties. Analogues of dihydrofolate reductase and firefly luciferase containing glycosylated amino acids at single, predetermined sites have been elaborated. Misacylated suppressor tRNAs activated with glycosylated serine and tyrosine derivatives were used for suppression of the nonsense codons in a cell-free protein biosynthesizing system, thereby permitting the preparation of the desired glycosylated proteins. In this fashion, it was possible to obtain proteins containing both mono- and diglycosylated amino acids, including glycosylated serine and tyrosine moieties. For the modified firefly luciferases, the effect of these substitutions on the wavelength of the light emitted by firefly luciferase was investigated. The maximum wavelength for mutants containing peracetylated glycosylated serine derivatives at position 284 showed a red shift in the emission spectra. For mutants containing glycosylated tyrosines, the red shift was observed only when the carbohydrate moiety was fully deacetylated.     

A novel microfluidic flow-injection analysis device with fluorescence detection for cation sensing. Application to potassium

A microfabricated device has been developed for fluorimetric detection of potassium ions without previous separation. It is based on use of a fluorescent molecular sensor, calix–bodipy, specially designed to be sensitive to and selective for the target ion. The device is essentially made of a Y-shape microchannel moulded in PDMS fixed on a glass substrate. A passive mixer is used for mixing the reactant and the analyte. The optical detection arrangement uses two optical fibres, one for excitation by a light-emitting diode, the other for collection of the fluorescence. This system enabled the flow-injection analysis of the concentration of potassium ions in aqueous solutions with a detection limit of 0.5 mmol L⁻¹ and without interference with sodium ions. A calibration plot was constructed using potassium standard solutions in the range 0–16 mmol L⁻¹, and was used for the determination of the potassium content of a pharmaceutical pill. Figure Photography of the microfluidic channel showing the ridges in the PDMS substrate at the top of the channel     

Electronic properties of 3,3'-dimethyl-5,5'-bis(1,2,4-triazine): towards design of supramolecular arrangements of N-heterocyclic Cu(I) complexes

A new efficient and safe synthesis of 3,3'-dimethyl-5,5'-bis-(1,2,4-triazine) is presented. The electron-density distribution and electrostatic properties (charge, electrostatic potential) of this molecule were analyzed. These properties were derived from a high-resolution single-crystal X-ray diffraction experiment at 100 K and compared to the results obtained from ab initio DFT quantum-mechanical calculations. Comparisons of its electrostatic potential features and integrated atomic charges (quantum theory of atoms in molecules, QTAIM) have been made with those of related molecules such as bipyrimidine ligands. Two methods were used to derive integrated charges: one is based on the conventional analytical procedure and the second uses a steepest-ascent numerical algorithm. Excellent agreement was obtained between these two methods. Charges and electrostatic potential were used as predictive indices of metal chelation and discussed in the light of complexation abilities of the title compound and related molecules. The crystal structure of a Cu(I) complex of 3,3'-dimethyl-5,5'-bis(1,2,4-triazine) is reported here. In the solid state, this complex forms a three-dimensional multibranch network with open channels in which counterions and solvent molecules are located. This architecture involves both cis and trans isomers of the title compound.     

Exact null controllability of the Lobesia botrana model with diffusion

This paper is devoted to analyze the exact null controllability of the diffusive Lobesia botrana model with nonlocal boundary condition. We study the null controllability of butterfly population by acting on eggs, larvas and female moths in a small age interval. We assume that the control of female moths is in a certain given region of the vineyard. The main result is established by combining some estimations and the Carleman inequality for the backward system related to an optimal control problem. A fixed point theorem is then used to draw the conclusion.     

Bimetallic Anionic Organic Frameworks with Solid-State Cation Conduction for Charge Storage Applications

A new phosphonate-based anionic bimetallic organic framework, with the general formula of A₄−Zn−DOBDP (wherein A is Li⁺ or Na⁺, and DOBDP⁶⁻ is the 2,5-dioxido-1,4-benzenediphosphate ligand) is prepared and characterized for energy storage applications. With four alkali cations per formula unit, the A₄−Zn−DOBDP MOF is found to be the first example of non-solvated cation conducting MOF with measured conductivities of 5.4×10⁻⁸ S cm⁻¹ and 3.4×10⁻⁸ S cm⁻¹ for Li₄- and Na₄- phases, indicating phase and composition effects of Li⁺ and Na⁺ shuttling through the channels. Three orders of magnitude increase in ionic conductivity is further attained upon solvation with propylene carbonate, placing this system among the best MOF ionic conductors at room temperature. As positive electrode material, Li₄−Zn−DOBDP delivers a specific capacity of 140 mAh g⁻¹ at a high average discharge potential of 3.2 V (vs. Li⁺/Li) with 90 % of capacity retention over 100 cycles. The significance of this research extends from the development of a new family of electroactive phosphonate-based MOFs with inherent ionic conductivity and reversible cation storage, to providing elementary insights into the development of highly sought yet still evasive MOFs with mixed-ion and electron conduction for energy storage applications.     

Hybrid of the 1,2,3-triazole nucleus and sesquiterpene skeleton as a potential antitumor agent: Hemisynthesis,molecular structure,Hirshfeld surface analysis,density functional theory,and in vitro cytotoxic and apoptotic effects

A new 1,2,3-triazole sesquiterpenic named (4aR,5aS,7aR,10aR,10bR)-10-benzyl-5,5-dichloro-1,1,4a,7a-tetramethyl-1,2,3,4,4a,5,7a,10,10a,10b decahydrocyclopropa[2′,3′]cyclohepta [1′,2′:3,4]benzo[1,2-d][1,2,3]triazol-7(6H)-one was synthesized by a dipolar cycloaddition 1,3 between benzyl azide and α,β-unsaturated sesquiterpene ketone catalyzed by titanium tetrachloride TiCl₄. It was obtained with a good yield and characterized using single-crystal X-ray diffraction technique, infra red (IR) spectroscopy, High Resolution Mass Spectrometry (HRMS), UV-Visible, and ¹H and ¹³C NMR spectroscopies. The optimization by the density functional theory (DFT) method was carried out to study the formation mechanism of the derivative. The selected compounds 1 – 4 exhibited anticancer activities in vitro against namely fibrosarcoma (HT-1080), lung carcinoma (A-549), and breast (MCF-7 and MDA-MB-231 cell lines with IC₅₀ in the range of 10.02–44.71 μM). In addition to using flow cytometry and the apoptosis assay, cell cycle arrest at the S phase (10 μM) and G2/M arrest in (5 and 10 μM) was performed for compound 4 in fibrosarcoma (HT-1080) cancer cells. Results suggested that compound 4 test with good activity against HT-1080 cells with IC₅₀ value from 10.02 μM and induced the apoptotic effect. Theoretical studies were realized to estimate the molecular proprieties that lead to a high potential of cytotoxic effect, which is in agreement with the experimental results.     

Electronic structure and coordination chemistry of phenanthridine ligand in first‐row transition metal complexes: A DFT study

The geometric parameters, electronic structures, and haptotropic migration of a series of hypothetical compounds of general formula CpM(C₁₃H₉N) and (CO)₃M(C₁₃H₉N) (M = fist row transition metal, Cp = C₅H₅, and C₁₃H₉N = phenanthridine ligand) are investigated by means of the density functional theory. The phenanthridine ligand can bind to the metal through η¹ to η⁶ coordination mode, in agreement with the electron count and the nature of the metal, showing its capability to adapt itself to the electronic demand of the metal as well as to the polycyclic aromatic hydrocarbons. In the investigated species, the most favored closed‐shell count is 18‐electron except for the Ti and V models which are deficient open‐shell 16‐electron configuration. This study has shown the difference in coordination ability of this heteropolycyclic ligand: the coordination of the central C₅N ring is less favored than the terminal C₆ rings, in agreement with the π‐electron density localization. Most of the investigated complexes are expected to exhibit a rich fluxional behavior. This flexibility favors the possibility for the existence of several isomers as well as their interconversion through haptotropic shifts. © 2012 Wiley Periodicals, Inc.     

Long argan fruit drying time is detrimental for argan oil quality

Argan oil is extracted from the kernels of argan fruits that have been sun-dried for either a few days or up to several weeks. The influence of the fruit drying time on the quantity, quality, and preservation of solvent-extracted argan oil was compared with press-extracted argan oil. Quantitatively, the time necessary for efficient fruit peeling and the amount of extracted oil were determined with regard to the fruit drying time (0 to 28 days). Argan oil quality was studied using, as markers, moisture content, specific extinction, acid index, peroxide index, fatty acid composition, and Rancimat oxidative stability. Oil from fresh fruit presents a high moisture content, high acidity and peroxide values, and short shelf life. Ten to fourteen days of sun-drying is optimum to obtain high quality argan oil.     

Thermal degradation of a reactive flame retardant based on cyclotriphosphazene and its blend with DGEBA epoxy resin

Hexaglycidyl cyclotriphosphazene (HGCP) was synthesized, and characterized by FTIR, ³¹P, ¹H, and ¹³C-NMR. This compound was used as a reactive flame retardant to blend with commercial epoxy resin DGEBA (Diglycidyl ether of bisphenol A). Its effect on the DGEBA decomposition pathways was characterized by studying both gas and solid phases produced during thermogravimetric analysis (TGA). The gases evolved during TGA in air were studied by means of thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR), while the solid residues were analysed by FTIR and scanning electron microscopy (SEM). The results showed that HGCP presents a good dispersion in DGEBA, and the blend thermoset with 4,4′-methylene-dianiline (MDA) curing agent leads to a significant improvement of the thermal stability at elevated temperature with higher char yields compared with pure DGEBA thermoset with the same curing agent. Improvement has also been observed in the fire behaviour of blend sample.     

Molecular docking study on β-cyclodextrin Interactions of metobromuron and [3-(p-bromophenyl)-1-methoxy-1-methylurea]

The inclusion process involving β-cyclodextrin (β-cyclodextrin-CD) and phenylurea herbicide metobromuron (MB) has been investigated by using the MM+, PM3, B3LYP, HF, ONIOM2 and NBO methods. The binding and complexation energies for both orientations considered in this research are reported. The geometry of the most stable complex shows that the aromatic ring is deeply self-included inside the hydrophobic cavity of β-CD also an intermolecular hydrogen bond is established between host and guest molecules. This suggests that hydrophobic effect and hydrogen bond play an important role in the complexation process. The statistical thermodynamic calculations by PM3 demonstrate that 1:1?MB/β-CD complex is favored by a negative enthalpy change. Moreover, NBO calculations proved also that are a very useful means to quantify the interaction energies of the hydrogen bonds.