The C-terminal binding protein 2 (CtBP2) plays a role in apoptosis and embryogenesis. Genetic knockout studies have been demonstrated to cause severe developmental defects and embryonic lethality. CtBP2 has three key domains and dimerizes for a significant role by binding with nicotinamide adenine dinucleotide (NADH). However, the molecular mechanism of CtBP2 dimerization and the effect of NADH binding are unknown. In this study, we performed molecular dynamics (MD) and docking simulation to reveal the mechanism of C-terminal binding protein 2 (CtBP2) dimerization and the effect of NADH binding on the dimer formation. Our MD simulation results detected seven salt bridges that are important for CtBP2 dimerization. And docking simulation demonstrated that the holo-monomer gave a higher probability of correct docking pose than the apo-monomer. Moreover, in docking simulation using a PXDLS model peptide, that holo form gave more docking poses than that apo form. These results suggested that the holo form has a structure that facilitates the formation of dimers and the binding of PXDLS peptides.
Hydroxyapatite nanowire (HAnW), a novel synthesized biocompatible material without any transition metals, was applied to catalytic degradation of antibiotics. Importantly, tetracycline (TC), a common drug, could be rapidly adsorbed and catalytically degraded by HAnW, and the removal reached 85% within 5 min at room temperature.
The nucleophilic addition of ketene silyl acetals 2 into 2H-azirines 1 proceeded in the presence of Lewis acids such as InX3 or Sc(OTf)3 to give N-unprotected aziridines 3. The mild Lewis acidity of the catalyst is important for the achievement of this coupling. The generated aziridine 3 could then be transformed into either oxazolines or γ–amino carbonyls.
Piperazine-containing compounds tend to exhibit good biological activities. In this study, four novel halogenated diphenylpiperazines were biosynthesized in one step by feeding halogenated L-tyrosine derivatives to Escherichia coli cells expressing heterologous non-ribosomal peptide synthetase HqlA and short-chain reductase HqlB. The work showed potential for synthesis of halogenated diphenylpiperazines using engineered microorganism.
An acid-degradable rotaxane consisting of a crown ether/ammonium salt complex was synthesized using a stopper compound bearing a tert-butyloxycarbonyl protecting group (Boc group). The unstable inclusion complex was stabilized by introducing a bulky Boc group at its end. The deprotection reaction via addition of trifluoroacetic acid resulted in the decomposition of rotaxane, as demonstrated by 1H nuclear magnetic resonance (NMR) and gel permeation chromatography measurement. The polymerization of rotaxane by metathesis reaction was also attempted.
Recent advances in guanidinium-based receptors are summarized emphasizing the high affinity of the guanidinium moiety towards certain anions in highly competitive aqueous media. Particularly the interaction with multivalent oxoanions such as phosphate, sulfate, chromate, or even pertechnetate is of great interest for recognition. This review summarizes additionally selected developments in guanidine synthesis that are the basis of guanidinium based receptors and functionalized materials with an advanced recognition of certain anions under interfacial aqueous condition.
Syndiotactic-polystyrene based porous polymers were obtained by polymerizations of styrene (St), 4-methyl styrene (MSt), or 4-tert-butyl styrene (BSt) and copolymerization of St/MeSt, St/BuSt, or St/divinylbenzene (DVB) using a half metallocene catalyst, pentamethyl cyclopentadienyl titanium trichloride (Cp*TiCl3), combined with methylaluminoxane (MAO) as a co-catalyst in a mixture of toluene and hexane (50/50 vol./vol.). The reaction systems turned opaque with progress of the polymerizations accompanied by phase separation. Bulk densities of the resultant polymers were much less than that of the bulk polystyrene. Scanning electron microscopy (SEM) images of the polymers showed a porous structure formed by networked fibers.
Effects of target-substrate (TS) distance during pulsed laser deposition process on the chemical structure and lithium-ion conductivity of amorphous lithium phosphate (LPO) thin films are investigated. The shorter TS distance results in lower Li concentration, longer phosphate chain, and higher ionic conductivity. The ionic conductivity of 2.7 × 10−7 S/cm is obtained at 25 °C in the LPO thin film with short TS distance.
An easy-to-handle sodium dispersion in paraffin oil (SD), in combination with inexpensive and environmentally benign 1,3-dimethyl-2-imidazolidinone (DMI) as an additive enables the Birch-type reduction of a variety of arenes with high yields, selectivity, and tolerance of functionality such as ether, alcohol, amine, amide, and carboxylic acid.
Synergetic effects were observed in an oriented-NaNbO3/g-C3N4 heterostructure system synthesized from in situ pyrolysis of urea with hydrothermally prepared NaNbO3 microcuboids. Chemically wrapping NaNbO3 with an appropriate amount of g-C3N4 forms an efficient heterojunction which separates photoexcited charges, and the internal electric field produced by oriented NaNbO3 grains facilitates their transfer. The mechanism developed here is applicable to enhancing photoelectrical utilization in other perovskite systems.
Supported nickel CHA-type zeolites with different framework compositions including borosilicate, gallosilicate and aluminosilicate were synthesized. The effect of heteroatoms in the framework on the state of the Ni species introduced was investigated. The size and dispersibility of the Ni species differed greatly depending on the heteroatom in the zeolite framework, and the use of the aluminosilicate-type framework led to the formation of a highly dispersed and nano-sized Ni species. Thus, prepared Supported Ni CHA-type aluminosilicate exhibited the highest catalytic performance in oxidative conversion of CH4.
A MnOOH-based mineral electrocatalyst for the oxygen evolution reaction was developed using a natural ore that is typically insulating, simply by applying a ball milling treatment. This material catalytically decomposed water molecules to generate oxygen. Mn K-edge X-ray absorption spectroscopy analyses in the bulk and surface sensitive modes indicated that structural distortion at the surface provided the catalytically active sites. The formation of oxygen vacancies on natural ore surfaces is likely to be the key to developing efficient mineral electrocatalysts.
Efforts to isolate compounds from an Indonesian member of the ginger family, Kaempferia angustifolia, yielded three known molecules, identified as (+)-crotepoxide (1), (+)-pipoxide chlorohydrin (2), and flavokawain A (FKA, 3). All three compounds strongly inhibited triglyceride accumulation in 3T3-L1 murine pre-adipocytes at 10 µg/mL, and compounds 1 and 2 were both cytotoxic at this concentration. To determine the biological activities of natural 3, flavokawains A (3), B (4) and C (5) were synthesized. While 4 was cytotoxic, both 3 and 5 potently inhibited differentiation of murine pre-adipocytes and reduced triglyceride accumulation (EC50 = 64.4 and 26.1 µM, respectively) with relatively weak cytotoxicity. Thus, the electron-donating group on the aromatic B ring may contribute to the highly selective anti-obesity activity.
At present, there are still challenges in the efficient synthesis of catalysts for water splitting hydrogen evolution. We propose herein a high-efficiency strategy to simply and quickly synthesize composites of Ni/NiO and carbon nanotubes. The Ni/NiO-loaded carbon nanotubes are prepared by oxidative combustion of ethanol over a metal-based catalyst and exhibit excellent catalytic performance for alkaline water splitting hydrogen evolution with 129 mV overpotential to offer a current density of 10 mA cm−2. Meanwhile, the Ni/NiO-loaded carbon nanotubes also exhibit good stability. The Ni/NiO-loaded carbon nanotubes obtained by the simple and fast preparation thus could be a promising electrocatalyst for hydrogen evolution rection.
We investigated the patterning of organic light-emitting diodes using a blue laser irradiation after making a uniform device. Laser patterning was carried out under ambient atmosphere after the organic layer was deposited. The laser irradiation part was quenched, and it was shown that optional patterning was possible. This technique is expected to be a fabrication technique for on-demand pattern emission.
Carbazole-containing 1,2-azaborine derivatives bearing various substituents were synthesized using bora-Friedel–Crafts reactions of 1,8-diphenylcarbazole derivatives, and the substituent effects on their photophysical properties were investigated. Furthermore, three carbazole-containing azaborine dimers with different annulation manners between the azaborine and benzene moieties were also successfully synthesized, and the effects of dimerization and differences in the annulation manners on their photophysical properties were disclosed.
Three kinds of heteroleptic Cu(I) complexes having a phenanthroline-based ligand acting as a chromophore and bearing benzoxazole, benzothiazole, and thiazole moieties were synthesized. Introduction into the phenanthroline ligands of electron-withdrawing five-membered aryl groups caused large red-shifts in the metal-to-ligand charge transfer bands, showing visible light absorption up to 500 nm. The obtained Cu(I) complexes exhibited emissions with quantum yields of 0.01–0.04 and long lifetimes of 0.4–3 µs.
We investigated the effect of linkers on the dynamics of cargo proteins by using a protein needle (PN) scaffold linked to superfolder green fluorescent proteins (sfGFPs) via various linkers. High-speed atomic force microscopy (HS-AFM) revealed clear images of the sfGFP motions on the PN. The results showed that the mobility of cargo proteins is affected by the flexibility and length of linker as well as the intermolecular interactions between the cargo protein and the scaffold protein.
Tetrasilabicyclo[1.1.0]but-1(3)-enes, compounds containing an Si=Si double bond with an inverted geometry, have recently emerged as a new class of stable π-electron systems of silicon. Herein, we report the synthesis of 2,4-diaminotetrasilabicyclo[1.1.0]but-1(3)-enes 1t and 1c that have amino groups at the bridge positions. XRD analysis and theoretical calculations revealed that inverted Si=Si double bonds in 1t and 1c lengthen up to 2.55 Å likely due to the interaction between the π(Si=Si) and σ*(Si–N) orbitals.
Colloidal metal nanoparticles were examined for reductive amination of phenol by ammonia under mild reaction conditions. The results showed that Rh-PVP was the most active catalyst for reductive amination reaction. Linear, cyclic, and amino alcohols were used as nucleophiles and converted to primary/secondary/tertiary amines. Using this strategy, the synthesis of an industrially important chemical, N-cyclohexyl-2-pyrrolidone was explored.
Persistent organic pollutants (POPs) are harmful organic compounds remaining in the environment for a long time, but are slowly degraded in the environment. Structural elucidation of the scarce amount of the POP degradation products is highly desired to understand the degradation process of the POPs. Herein, we demonstrated the crystalline sponge (CS) method, a crystallization-free X-ray crystallography technique on the nanogram to microgram scale, is quite efficient for the analysis of a series of representative POP compounds. The X-ray structures of three POPs were reported for the first time. Halogen interactions take a key role in the molecular recognition in the CS pores.
This study investigated non-oxidative propane dehydrogenation over TiH2. It was found that H2 co-feeding positively affected dehydrogenation, improving the propylene formation rate. In situ spectroscopic characterization of TiH2 in the presence of H2 indicated that partially dehydrogenated titanium hydrides are active for dehydrogenation.