A Novel Catalyst for Isobutene Oligomerization to High Quality Gasoline

Dimerization of isobutene in liquid state to form high-octane value gasoline components was investigated over a homemade novel ion exchange resin,SPPESK,which shows high activity and selectivity in isobutene dimerization under mild conditions.     

Two-Step Purification of a Novel β-Glucosidase with High Transglycosylation Activity and Another Hypothetical β-Glucosidase in Aspergillus oryzae HML366 and Enzymatic Characterization

Two novel β-glucosidases (BGHG1 and BGHG2) were purified from the enzyme extract of Aspergillus oryzae HML366 through nondenaturing gel electrophoresis and anion-exchange chromatography. The molecular weights for BGHG1 and BGHG2 were 93 and 138 kDa, respectively. The amino acid sequences were determined by matrix-assisted laser desorption/ionization tandem time of flight. The Mascot and Blast analyses indicated that BGHG1 has the same sequence as the hypothetical protein XP_001816831 from A. oryzae RIB40. Sequence comparison suggested that both enzymes belong to the glycosyl hydrolase family 3. Results from thin layer chromatography and high performance liquid chromatography showed that BGHG2 has relatively high transglycosylation activity, and after preliminary optimization, it was able to convert glucose to produce 52.48 mg/ml gentiobiose. This is the first report of production of hypothetical protein XP_001816831 and β-glucosidase with high transglycosylation activity in A. oryzae. Results provide a valuable reference for potential applications in food industry, biomass power generating industry, and many others.     

A Novel Method for Conversion of Valuable BDS Intermediates HPBS／Cx-HPBS from DBT／Cx-DBT

A simple recombinant PCR method was used to delete the dszB gene responsible for the slowest step of the Dsz pathway and allow the accumulation of hydroxyphenyl benzene sulfinate (HPBS) in the recombinant E. coll. Using GC/MS, HPBS accumulation was confirmed. The recombinant E.coli could also desulfurize Cx-DBT to corresponding Cx-HPBS. The result gave a new insight to BDS process and explored a new method to obtain valuable surfactants from cheap raw materials.     

Purification and Characterization of an Ethanol-Tolerant β-Glucosidase from Sporidiobolus pararoseus and Its Potential for Hydrolysis of Wine Aroma Precursors

An extracellular ethanol-tolerant β-glucosidase from Sporidiobolus pararoseus was purified to homogeneity and characterized, and its potential use for the enhancement of wine aroma was investigated. The crude enzymatic extract was purified in four steps (concentration, dialysis, ultrafiltration, and chromatography) with a yield of around 40 % for total activity. The purified enzyme (designated Sp-βgl-P) showed a specific activity of approximately 20.0 U/mg, an estimated molecular mass of 63 kDa after sodium dodecyl sulfate polyacrylamide gel electrophoresis, and isoelectric point of 5.0 by isoelectric focusing. Sp-βgl-P has optimal activity at pH 4.0 and at 55 °C. It was stable in a broad pH range at low temperatures and it was tolerant to ethanol and glucose, indicating suitable properties for winemaking. The hydrolysis of glycosidic terpenes was analyzed by adding Sp-βgl-P directly to the wines. The released terpene compounds were evaluated by gas chromatography/mass spectrometry. The enzymatic treatment significantly increased the amount of free terpenes, suggesting that this enzyme could potentially be applicable in wine aroma improvement.     

Gene Cloning and Characterization of a Novel Salt-Tolerant and Glucose-Enhanced β-Glucosidase from a Marine Streptomycete

The gene BglNH encoding a β-glucosidase was cloned from a marine streptomycete. Sequence analysis revealed that BglNH encoded a 456-aa peptide with a calculated mass of 51 kDa. The deduced amino acid sequence of BglNH showed the highest identities of 61 % with known β-glucosidases and contained a catalytic domain which belonged to the glycoside hydrolase family 1. The gene BglNH was expressed in Escherichia coli and the recombinant enzyme (r-BglNH) was purified. The optimum pH and temperature of r-BglNH were pH?6.0 and 45 °C, respectively. The r-BglNH displayed the typical salt-tolerant and glucose-enhanced characteristics. Its activity was remarkably enhanced in the presence of 0.5 M NaCl (rose more than 1.6-fold) and 0.1 M glucose (rose more than 1.4-fold). Moreover, r-BglNH displayed good pH stability and metal tolerance. It remained stable after incubating with buffers from pH?4.0 to 10.0, and most metal ions had no significant inhibition on its activity. These properties indicate that r-BglNH is an ideal candidate for further research and industrial applications.     

A Novel Cobalt（Ⅲ） Complex with Macrocyclic Triamine Ligand for High Capacity Hydrogen Adsorption

The coordination complex of Co(Ⅲ) based on a macrocyclic triamine ligand 1,4-diacetate-1,4,7-triazacyclodecane (L) has been synthesized and characterized. The metal cation is bonded with three nitrogen atoms and two oxygen atoms of L and one chloride ion to form a distorted octahedral geometry. This complex coordinated with macrocyclic ligand possesses large pore volume that will be contributed to observe high H2 adsorption. With respect to the first-principles electronic structure calculations, the feasibility to store hydrogen in the complex is explored. Indeed, the complex has shown a very high total H2 adsorption of 7.2 wt% (wt% = (weight of adsorbed H2)/(weight of host material)), with a binding energy of 0.03 eV/H2.     

Reaction of Polyfluorinated β-Diimines with Ketones. A Novel Method for the Synthesis of Fluorinated Pyridines

Reaction of polyfluorinated -diimines with ketones gave polyfluorinated pyridines     

A Convenient Method for the Conversion of α-Tetralones to Aryl Acetates

A facile synthesis of aryl acetates from α-tetralone has been performed with isopropenyl acetate and p-toluenesulfonic acid, followed by dehydrogenation with air or DDQ, in a one-pot procedure.     

Trichoderma harzianum IOC-4038: A Promising Strain for the Production of a Cellulolytic Complex with Significant β-Glucosidase Activity from Sugarcane Bagasse Cellulignin

Sugarcane bagasse is an agroindustrial residue generated in large amounts in Brazil. This biomass can be used for the production of cellulases, aiming at their use in second-generation processes for bioethanol production. Therefore, this work reports the ability of a fungal strain, Trichoderma harzianum IOC-4038, to produce cellulases on a novel material, xylan free and cellulose rich, generated from sugarcane bagasse, named partially delignified cellulignin. The extract produced by T. harzianum under submerged conditions reached 745, 97, and 559 U L⁻¹ of β-glucosidase, FPase, and endoglucanase activities, respectively. The partial characterization of this enzyme complex indicated, using a dual analysis, that the optimal pH values for the biocatalysis ranged from 4.9 to 5.2 and optimal temperatures were between 47 and 54 °C, depending on the activity studied. Thermal stability analyses revealed no significant decrease in activity at 37 °C during 23 h of incubation. When compared to model strains, Aspergillus niger ATCC-16404 and Trichoderma reesei RutC30, T. harzianum fermentation was faster and its extract showed a better balanced enzyme complex, with adequate characteristics for its application in simultaneous saccharification and fermentation processes.     

A One-Step Procedure for Facile Preparation of D-Glucopyranosides with a free 2-OH from O-Peracetylated β-D-Glucopyranose

ABSTRACT

Glycosylations and deacetylations of 2-O-acetyl of O-peracetylated β-D-glucopyranose were realized in one step by reactions with 4.0 equivalents of alcohols and 1.5 equivalents of trifluoroborane etherate. Thus, various β-D-glucopyranosides with a free hydroxyl group on C-2 were conveniently prepared and applied for synthesis of Glcl → 2 linked disaccharides.

     

A Novel Electrochemical Sensor Based on Reduced Graphene Oxide–TiO2 Nanocomposites with High Selectivity for the Determination of Hydroxychloroquine

Russian Journal of Electrochemistry - A simply sensitive sensor based on a reduced graphene oxide–TiO2 nanocomposite modified glassy carbon electrode (RGO–TiO2/GCE) was developed for...     

Zeolite Molecular Sieve 4Å: A Reusable Catalyst for Fast and Efficient Conversion of Epoxides to Thiiranes with Thiourea

Abstract

Various epoxides are readily converted to their corresponding thiiranes by thiourea/zeolite molecular sieve 4Å system in refluxing MeOH. All reactions were carried out within 12–25 min to give thiiranes in 80%–99% yields. The catalyst saves its catalytic activity for several times at this transformation. Stereospecific conversion of (R)-(+)-styrene oxide to (S)-(+)-styrene episulfide was achieved by this combination system.

GRAPHICAL ABSTRACT      

A Novel Cold-Active and Alkali-Stable β-Glucosidase Gene Isolated from the Marine Bacterium <Emphasis Type="BoldItalic">Martelella mediterranea</Emphasis>

A β-glucosidase gene designated gluc3m was cloned through construction of a genomic library of Martelella mediterranea 2928. The gluc3m consisted of 2,496 bp and encoded a peptide of 832 amino acids that shared the greatest amino acid similarity (59%) with a β-glucosidase of family 3 glycoside hydrolase from Agrobacterium radiobacter K84. The optimum reaction temperature and pH of Gluc3M were 45 °C and 8.0, respectively. The K _m and V _max for p-nitrophenyl-β-d-glucopyranoside were 0.18 mg/ml and 196.08 μmol/min/mg enzyme, respectively. Gluc3M was found to be highly alkali stable, retaining 80% of its maximum enzymatic activity after treatment with pH 11.0 buffers for 24 h. Furthermore, the activity of Gluc3M improved remarkably in the presence of univalent metal ions, whereas it was inhibited in the presence of divalent ions. Gluc3M also exhibited significant activities toward various substrates including pNPGlu, pNPGal, salicin, and konjac powder. It is important to note that Gluc3M is a cold-active enzyme that showed over 50% of the maximum enzymatic activity at 4 °C. SWISS-MODEL revealed that the amino acids near the conserved domain SDW of Gluc3M contributed to the cold-active ability. Based on these characteristics, Gluc3M has the potential for use in additional studies and for industrial applications.     

A Novel Method for Preparing Approximately Micron-sized Polymethyl Methacrylate Microspheres with Clear Surface

Polymethyl methacrylate (PMMA) microspheres with clear surface and diameter close to 1μm were synthesized by newly soap-free emulsion polymerization. The results showed that the presence of ethanol and NaCl made the increase of diameter and distribution, while the presence of toluene could avoid the problem of the increase of distribution, resulting a harvest of PMMA microspheres with a diameter close to 1μm.     

The Reaction of β-Aminoenones with Cyanamide. A High Efficient Synthesis of 2-Aminopyrimidines

β-aminoenones react with cyanamide, molar ratio 1:2, to yield 2-aminopyrimidines in nearly quantitative yields.     

Metastable β-Bi2O3 Nanoparticles with Potential for Photocatalytic Water Purification Using Visible Light Irradiation

Invited for this month′s cover is the group of Prof. Michael Mehring. The cover picture shows the degradation of the model dye rhodamine B (RhB) in water using β-Bi₂O₃ nanoparticles as photocatalyst, which was prepared from pre-organized bismuth oxido clusters. For more details, see the Full Paper on p. 146 ff.The Group of Michael MehringTechnische Universität Chemnitz Fakultät für Naturwissenschaften, Institut für Chemie Professur Koordinationschemie 09111 Chemnitz (Germany) E-mail: ed.ztinmehc-ut.eimehc@gnirhem.leahcim     

A pH-responsive carboxylic β-1,3-glucan polysaccharide for complexation with polymeric guests

The helix-forming nature of β-1,3-glucan polysaccharides is a characteristic that has potential for producing gene carriers, bio-nanomaterials and other chiral nanowires. Herein, carboxylic curdlan (CurCOOH) bearing the β-1,3-polyglucuronic acid structure was successfully prepared from β-1,3-glucan polysaccharide curdlan (Cur) by one-step oxidation using a 4-acetamido-TEMPO/NaClO/NaClO(2) system as the oxidant. The resulting high-molecular-weight CurCOOH was proved to bear the 6-COOH group in 100% purity. The optical rotatory dispersion (ORD) spectra indicated that the obtained CurCOOH behaves as a water-soluble single-strand in various pH aqueous media. This advantage has allowed us to use CurCOOH as a polymeric host to form various macromolecular complexes. For example, complexation of CurCOOH with single-walled carbon nanotubes (SWNTs) resulted in a water-soluble one-dimensional architecture, which formed a dispersion in aqueous solution that was stable for several months, and much more stable than SWNTs complexes of the similar negatively-charged polyacrylic acid (PAA) and polymethacrylic acid (PMAA). It was shown that in the complex, SWNTs are effectively wrapped by a small amount of CurCOOH, enabling them to avoid electrostatic repulsion. This pH-responsive CurCOOH formed a very stable complex with cationic water-soluble polythiophenes (PT-1), which was stabilized not only by the hydrophobic interaction but also by the electrostatic attraction between trimethylammonium cations in PT-1 and dissociated anionic COO(-) groups in CurCOOH. The included PT-1 became CD-active only in the neutral to basic pH region, and the positive Cotton effect suggested that the conjugated main chain is twisted in the right-handed direction. We also found that CurCOOH can interact with polycytidylic acid (poly(C)) only under high NaCl concentrations, the binding and release of which could be controlled by a change in the salt concentration. We believe, therefore, that CurCOOH bearing a dissociable COOH group can act as a new potential polymeric host to construct novel polymeric complexes applicable for gene carriers, biosensors, chiral polymer assemblies, etc.     

Two Coordination Polymers with High Selectivity for Sensing Iron(Ⅲ) Constructed from Bifunctional Ligand

A new ligand [1-{2-(2-pyridyl)-benzo[d]imidazole}-2-(5-hydroxyisophthalic acid) ethane] was used to synthesize cadmium and cobalt based florescent organic frameworks successfully under solvothermal conditions. Single-crystal X-ray crystallography of both complexes as well as their thermal stability and luminescence properties was investigated. Much emphasis was placed on the newly synthesized Cd-complex which shows great sensitivity for the detection of Fe~(3+) ions and could be used as a potential probe to detect the Fe~(3+) ions.