Beta-arrestin inhibits CAMKKbeta-dependent AMPK activation downstream of protease-activated-receptor-2

Background  

Proteinase-activated-receptor-2 (PAR₂) is a seven transmembrane receptor that can activate two separate signaling arms: one through Gαq and Ca²⁺ mobilization, and a second through recruitment of β-arrestin scaffolds. In some cases downstream targets of the Gαq/Ca²⁺ signaling arm are directly inhibited by β-arrestins, while in other cases the two pathways are synergistic; thus β-arrestins act as molecular switches capable of modifying the signal generated by the receptor.     

Study of <Emphasis Type="Italic">cis</Emphasis>–<Emphasis Type="Italic">trans</Emphasis> isomerization mechanism of 3,3′-azobenzene disulphonate in the lowest singlet and triplet electronic states by density functional theory

Abstract  

The cis–trans isomerization pathways of 3,3′-azobenzene disulphonate in the S₀ and T₁ states are studied by DFT method at the B3LYP/6-31G(d,p) level. In the S₀ state, the cis–trans isomerization concerns the complex pathway that is characterized by the inversion of one NNC angle combined with rotation around the NC bond, and the three sequential transition states are also found on the potential energy profile. Therefore, the cis–trans isomerization of 3,3′-azobenzene disulphonate can be understood in terms of a pathway involving successive rotation, inversion, and rotation processes. The energy barrier of the S₀ state is 22.79 kcal mol⁻¹. In the T₁ state, the isomerization mainly concerns the rotational pathway around the NN double bond, and the two isomers are connected through only one transition state. The isomerization of the T₁ state is related to a lower energy barrier, 5.02 kcal mol⁻¹, but requires a change in spin-multiplicity.     

Theoretical study on the protonation of cucurbit[6]uril

Abstract  

The most probable structures of the cucurbit[6]uril·H₃O⁺ and cucurbit[6]uril·(H₃O⁺)₂ cationic complex species have been derived by quantum mechanical DFT calculations. In these two complexes, each of the H₃O⁺ ions is bound by three strong linear hydrogen bonds to three carbonyl oxygen atoms of the parent macrocycle.     

A facile and improved synthesis of desomorphine and its deuterium-labeled analogue

Abstract  

This work describes a convenient and improved process for the synthesis of desomorphine from codeine. The proposed method affords the highly pure opiate without the aid of chromatographic purification, and provides a simple route for the synthesis of [²H₃] deuterium-labeled desomorphine.     

Theoretical study on the protonation of bambus[6]uril

Abstract  

Quantum mechanical density functional theory (DFT) calculations were used to derive the most probable structures of the bambus[6]uril·H₃O⁺ and bambus[6]uril·(H₃O⁺)₂ cationic complex species. In these two complexes, each of the considered H₃O⁺ ions is bound by three strong linear hydrogen bonds to the three corresponding carbonyl oxygens of the parent macrocyclic receptor.     

Chemistry of chromium bis-acetylide complexes

Abstract  

Stable paramagnetic Cr(II) and Cr(III) bis(alkynyl) complexes of the type [trans(RC≡C)₂Cr(dmpe)₂] ⁿ⁺ (R = Ph, SiMe₃, SiEt₃, C≡C–SiMe₃ n = 0, 1) were prepared and characterised by NMR, cyclic voltammetry, EPR, magnetic measurements, and X-ray single-crystal diffraction studies.     

Stability constants of the Li+, Na+, H3O+, NH4+, Ag+, and K+ complexes of the cone conformer of tetraethyl p-tert-butyltetrathiacalix[4]arene tetraacetate in nitrobenzene saturated with water

Abstract  

From extraction experiments in the two-phase water–nitrobenzene system and γ-activity measurements, the stability constants of the tetraethyl p-tert-butyltetrathiacalix[4]arene tetraacetate (cone)·M⁺ complexes (M⁺ = Li⁺, H₃O⁺, NH₄ ⁺, Ag⁺, or K⁺) were determined in water-saturated nitrobenzene. It was found that these constants increase in the cation order NH₄ ⁺ < K⁺ < H₃O⁺ < Ag⁺ < Li⁺ < Na⁺.     

Thermodynamic data for lanthanoid(III) sequestration by phytate at different temperatures

Abstract  

The results of an investigation on the interactions between phytate ion (myo-inositol hexaphosphate, Phy) and some lanthanoid cations (La³⁺, Nd³⁺, Sm³⁺, Dy³⁺, and Yb³⁺) are reported. The stability constants of various LnH _j Phy species (Ln = generic lanthanoid) were determined by potentiometry (ISE-H⁺ glass electrode) in NaCl_aq at I = 0.15 mol dm⁻³ and t = 25 °C, and the corresponding formation enthalpies by calorimetric titration. The thermodynamic data obtained were used to provide a speciation scheme for the lanthanoid(III)–phytate systems at different temperatures. The sequestering ability of this ligand toward Ln³⁺ was also evaluated by calculation of pL₅₀ values (the total concentration of ligand necessary to bind 50% of a cation present in trace amounts) under different conditions, and equations were formulated to model their dependence on temperature and pH.     

Photophysical properties of lanthanide complexes with 5-nitro-1,10-phenanthroline

Abstract  

Five novel lanthanide (Eu³⁺, Tb³⁺, Sm³⁺, Dy³⁺, and Gd³⁺) complexes with 5-nitro-1,10-phenanthroline (phenNO₂) have been synthesized and characterized by elemental analysis, IR, UV, and luminescence spectra. The triplet state energy of phenNO₂ was determined to be 20,048 cm⁻¹ via the phosphorescence spectra of phenNO₂ and its gadolinium complex. The photophysical properties of these complexes indicated that the triplet state energy of the ligand is suitable for the sensitization of the luminescence of Eu³⁺ and Sm³⁺, especially the former.     

Synthesis, characterization, and crystal structural study of the iron(II) 4,4′-bithiazole complex [Fe(C6H4N2S2)3]2+(NO3?)2

Abstract  

The complex [Fe(C₆H₄N₂S₂)₃]²⁺(NO₃⁻)₂ was prepared from the reaction of 4,4′-bithiazole with Fe(NO₃)₃·9H₂O in methanol. It was characterized by IR, UV-Vis, luminescence, ¹H NMR and ¹³C NMR spectroscopy, and X ray crystallography. The structure was solved in the orthorhombic space group P2₁2₁2₁ with a = 12.1500(5), b = 12.8434(6), c = 16.2222(7) ?, V = 2531.43(19) ?³, Z = 4, and with wR ₂  = 0.0897.     

Ab initio classical trajectory calculations of 1,3-cyclobutanedione radical cation dissociation

Abstract  

The dissociation of 1,3-cyclobutanedione radical cation was studied by ab initio direct classical trajectory calculations at the BH&HLYP/6-31G(d) level of theory. A microcanonical ensemble using normal mode sampling was constructed by distributing 10 kcal/mol of excess energy above the transition state for the tautomerization of the keto-enol to the diketo form. A total of 210 trajectories were run starting from this transition state, yielding chemically activated 1,3-cyclobutanedione radical cation. The majority of the trajectories resulted in CH₂CO^+· + CH₂CO, with the activated CC bond breaking nearly twice as often as the spectator CC bond. The non-statistical behavior is observed because the rate of energy redistribution within the molecule is comparable to or slower than the dissociation rates. In addition to the expected products, dissociation to CH₂COCH₂^+· + CO and formation of a proton-transferred product HCCO^· + CH₃CO⁺ were also seen in some of the trajectories.     

Rapid solidification of cryolite and cryolite–alumina melts

Abstract  

Rapid solidification processing (with a cooling rate in the interval 10⁵–10⁶ K s⁻¹) was used to prepare deeply undercooled cryolite–alumina melts. These samples were analyzed by XRD, infrared, and Raman spectroscopy. Besides cryolite, the amorphous phase and a low amount of ι-Al₂O₃ were detected. Annealing of the quenched sample revealed the transformation of metastable amorphous phases into different products depending on the annealing conditions. The results obtained showed that all of the elements (Na, Al, O, and F) are probably present in the amorphous parts of the quenched samples.     

Do the O<Subscript>2</Subscript> Schumann–Runge Bands Participate in keV Collision-Induced Dissociation Experiments?

In high-energy (keV) CID experiments, oxygen has the unique ability to enhance specific ion fragmentation pathways that lie within a relatively narrow band of activation energy. It has been previously proposed that this oxygen-enhanced dissociation phenomenon is due to the participation of the O₂  B ³S_u ⁺ - X ³S_g ^- {{\hbox{O}}_{{2}}}\;{\hbox{B}}{\,^{{3}}}{\Sigma_{\rm{u}}}^{ + } - {\hbox{X}}{\,^{{3}}}{\Sigma_{\rm{g}}}^{ - } (Schumann–Runge) system in the collision complex. During the collision, oxygen is first excited to its B ³S_u ⁺ {\hbox{B}}{\,^{{3}}}{\Sigma_{\rm{u}}}^{ + } state before it returns this energy to the projectile ion. This energy drives the nonstatistical dissociation of the projectile provided there is an energetically accessible pathway in resonance with the absorbed radiation. To probe the validity of this hypothesis, a modified VG-ZAB mass spectrometer was used to observe the photon emissions from keV collisions of a selection of projectile ions with O₂ target gas. By studying the resulting collision-induced emission (CIE) spectra, a second potential mechanism came to light, one that involves the near-isoenergetic O₂ ^+. A ²Π_u→X ² Π_g state transition.     

Spectral characterization of novel <Emphasis Type="Italic">bis</Emphasis> heterocycles comprising both piperidine and thiohydantoin nuclei

Abstract  

A series of bis heterocycles comprising both piperidine and thiohydantoin nuclei namely 3-(3-alkyl-2,6-diarylpiperin-4-ylidene)-2-thioxoimidazolidin-4-ones is synthesized and characterized by melting point, elemental analysis, MS, FT–IR, one-dimensional NMR (¹H, D₂O exchanged ¹H and ¹³C), two-dimensional HOMOCOSY, and NOESY spectroscopic data.     

Synthesis of 5-spirocyclohexyl-2,4-dithiohydantoin derivatives: a potential anti-leishmaniasis agent

Abstract  

A series of spiro-dithiohydantoins were synthesized by heating a mixture of 5-spirocyclohexyl-2,4-dithiohydantoin potassium salt and 3-chloropropanoyl chloride. These compounds were synthesized and evaluated for their activity against five Leishmanial strains in the promastigote stage in vitro. Seventy-two hours inoculation of a variety of products gave an IC ₁₀₀ and average IC ₅₀ values of 1.25 and 0.376 mg/cm³ against all Leishmanial strains tested.     

Solvothermal syntheses and crystal structures of two new thiogermanates [M(dap)3]4Ge4S10Cl4 (M?=?Co, Ni) with metal complexes as counterions

Abstract  

Two new transition-metal thiogermanates [M(dap)₃]₄Ge₄S₁₀Cl₄ (M = Co, Ni; dap = 1,2-propanediamine) have been solvothermally synthesized and structurally characterized. The two thiogermanates are isostructural and consist of discrete Ge₄S₁₀⁴⁻ adamantane-like ions, free Cl⁻ ions, and [M(dap)₃]²⁺ cations as counterions. The Ge₄S₁₀⁴⁻ anion is built from corner-sharing connection of four GeS₄⁴⁻ tetrahedra. Although some chalcogenidogermanates have been obtained by use of in situ generated transition-metal complexes as structure-directing agents under mild solvothermal conditions, their anions are usually dimeric [Ge₂Q₆]⁴⁻ (Q = S, Se) species. The new thiogermanates are rare examples of adamantane-like (Ge₄S₁₀⁴⁻) thiogermanates combined with transition-metal complexes. Their optical properties have been investigated by UV–Vis spectra.     

A Series of 1-D Lanthanide Coordination Polymers Based on [Ln4(μ3-OH)4] (Ln = Er, Tb, Gd) Cluster Units

Abstract  

A series of 1-D lanthanide coordination polymers [Ln(μ₃-OH)(pybz)(pa)] _n (Ln = Er (1), Tb (2), Gd (3), Hpybz = 4-pyridin-4-yl-benzoic acid, Hpa = 2-picolinic acid) based on [Ln₄(μ₃-OH)₄] cluster units have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, IR, elemental analysis, and thermogravimetric analysis. X-ray crystal structure analyses reveal that 1–3 are isomorphous with tetragonal space group P [`4] \overline{4} 2₁c and comprise tetranuclear Ln–O clusters, in which four Ln³⁺ centers are joined together by four μ₃-bridging hydroxyl groups to form cubane-like [Ln₄(μ₃-OH)₄]⁸⁺ cores that are further linked by four μ₃-pa⁻ ligands to produce 1-D chains along the c-axis.     

The influence of tetramethylthiourea on a two-step Zn2+ ion electroreduction in concentrated NaClO4 solutions

Abstract  

A two-step Zn²⁺ ion reduction was estimated at the dropping mercury electrode in 2, 3, and 4 mol dm⁻³ NaClO₄ with the addition of tetramethylthiourea using an impedance method at wide potential and frequency ranges. With increasing tetramethylthiourea and NaClO₄ concentrations the k_{\texts 1} ^t k_{{{\text{s}}_{ 1} }}^{t} and k_{\texts 2} ^t k_{{{\text{s}}_{ 2} }}^{t} values increased, achieving their maximum values at the highest concentrations of tetramethylthiourea in 3 and 4 mol dm⁻³ NaClO₄ solutions. The catalytic effect of tetramethylthiourea at its lowest employed concentration increased with increasing NaClO₄ concentration.     

Dissolving the insoluble: CdF<Subscript>2</Subscript> and moist ammonia form cadmium(II) difluoride monohydrate—synthesis and crystal structure of [Cd(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]F<Subscript>2</Subscript>·H<Subscript>2</Subscript>O

Abstract  

Hexaamminecadmium(II) fluoride monohydrate (1:1) [Cd(NH₃)₆]F₂·H₂O was synthesized from CdF₂ and liquid ammonia in open reaction vessels, so that moisture from the air was in contact with the solvent. The compound crystallizes in the chiral space group P3₁21- (No. 152) in the form of needle-shaped, colorless crystals with a = 6.8974(1) ?, c = 17.7156(5) ?, V = 729.89(3) ?³, and Z = 3.