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Steroidal C7β alcohols and their respective esters have shown significant promise as neuroprotective and anti‐inflammatory agents to treat chronic neuronal damage like stroke, brain trauma, and cerebral ischemia. Since C7 is spatially far away from any functional groups that could direct C−H activation, these transformations are not readily accessible using modern synthetic organic techniques. Reported here are P450‐BM3 mutants that catalyze the oxidative hydroxylation of six different steroids with pronounced C7 regioselectivities and β stereoselectivities, as well as high activities. These challenging transformations were achieved by a focused mutagenesis strategy and application of a novel technology for protein library construction based on DNA assembly and USER (Uracil‐Specific Excision Reagent) cloning. Upscaling reactions enabled the purification of the respective steroidal alcohols in moderate to excellent yields. The high‐resolution X‐ray structure and molecular dynamics simulations of the best mutant unveil the origin of regio‐ and stereoselectivity., One mutant, six targets: The regio‐ and stereoselective C−H activation for hydroxylation of six different steroids with formation of C7β alcohols was accomplished using a single P450 mutant evolved by protein library construction based on a special DNA assembly and cloning procedure. The C7β steroidal alcohols, not readily accessible by synthetic reagents or catalysts, are of intense interest as therapeutic drugs.

Multiple functional-material-filled nitrile butadiene rubber/chloroprene rubber (NBR/CR) acoustic composites were extensively studied and prepared. According to the orthogonal test table L25 (56), 25 groups of samples were prepared by using a low-temperature one-time rubber mixing process. With tensile strength, average transmission loss, and damping peak as indexes, the influence degree of different factors and levels on the properties of acoustic composites was quantitatively discussed and analyzed. The matrix weight analysis was employed to optimize the material formula of rubber composites, and the corresponding influence weight was given. Results showed that the acoustic composite with blending ratio of 70/30 for NBR/CR matrix had preferable mechanical and acoustic properties; adding mica powder (MP) and montmorillonite (MMT) in matrix contributed to improve all above three indexes owing to their specific lamellar structures; hollow glass beads (HGB) had a positive influence on improving acoustic property due to its hollow microcavities, however, it had a negative impact on damping property because of the smooth spherical surfaces. Accordingly, the optimal formulation was found to be NBR/CR blending ratio of 70/30, MP of 10 phr (per hundred rubber), HGB of 4 phr, and MMT of 10 phr.

Tetrahydroisoquinolines (THIQs) with a C1-aryl-substituted groups are common in many natural and synthetic compounds of biological importance. Currently, their enantioselective synthesis are majorly reliant on chemical catalysis. Enzymatic synthesis using imine reductase is very attractive due to the cost-effectiveness, high catalytic efficiency and enantioselectivity. However the steric-hindrance of the 1-aryl substituents make this conversion very challenging, and current successful examples are most-ly restricted to the simple alkyl-THIQs. In this report, through extensive evaluation of a large collection of IREDs (including 88 novel enzymes), we successfully identified a panel of steric-hindrance tolerated IREDs. These enzymes are able to convert me-ta-, para-substituted chloro-, methyl-, and methoxyl-benzyl DHIQs (dihydroisoquinolines) into corresponding R- or S- THIQs with very high enantioselectivity and conversion. Among them, the two most hindrance-tolerated enzymes (with different ste-reo-specif...

An artificial approach has been developed for efficient biosynthesis of plant tetrahydroisoquinoline alkaloids from dihydroisoquinoline precursors., Herein, we report a biocatalytic approach to synthesize plant tetrahydroisoquinoline alkaloids (THIQAs) from dihydroisoquinoline (DHIQ) precursors using imine reductases and N-methyltransferase (NMT). The imine reductase IR45 was engineered to significantly expand its substrate specificity, enabling efficient and stereoselective conversion of 1-phenyl and 1-benzyl 6,7-dimethoxy-DHIQs into the corresponding (S)-tetrahydroisoquinolines (S-THIQs). Coclaurine N-methyltransferase (CNMT) was able to further efficiently convert these (S)-THIQ intermediates into (S)-THIQAs. By assembling IRED, CNMT, and glucose dehydrogenase (GDH) in one reaction, we effectively constituted two artificial biosynthetic pathways in Escherichia coli and successfully applied them to the production of five (S)-THIQAs. This highly efficient (100% yield from DHIQs) and easily tailorable (adding other genes) biosynthetic approach will be useful for producing a variety of plant THIQAs.

Background and PurposeTransient receptor potential canonical (TRPC) channels play important roles in a broad array of physiological functions and are involved in various diseases. However, due to a lack of potent subtype-specific inhibitors the exact roles of TRPC channels in physiological and pathophysiological conditions have not been elucidated.

Amorphous photonic crystals display isotropic photonic band gaps and angle-independent non-iridescent, structural color, which leads to increasing interest and promising applications in image display, laser light, environment-friendly ink/coating, etc. However, previous amorphous photonic crystals usually exhibit low strength, and their structure is easily destroyed. Thus, their unique optical properties cannot be fully exhibited. Herein, amorphous photonic crystals of core (polystyrene-PSt) and shell (poly (4-methacryloyloxybenzophenone)-PMABP) structured microspheres are formed. Using polymer films (PET, PP, PMMA and PE) coated with poly (4-(methacryloxy) benzophenone-co-N-Isopropyl acrylamide) as substrates, the amorphous photonic crystals are immobilized under UV-irradiation. Adding cross-linker of ethoxylated trimethylolpropane triacrylate (ETPTA) in microsphere dispersion, transparent and flexible free-standing films of photonic crystals are fabricated. Angle-independent structural colors are observed and tuned by varying microsphere concentration in dispersions and content of cross-linker.

Transient receptor potential canonical 3/6/7 (TRPC3/6/7) are highly homologous receptor-operated non-selective cation channels. Despite their physiological significance, very few selective and potent agonists are available for functional examination of these channels. Using a cell-based high throughput screening approach, a lead compound with the pyrazolopyrimidine skeleton was identified as a TRPC6 agonist. Synthetic schemes for the lead and its analogues were established, and structural–activity relationship studies were carried out. A series of potent and direct agonists of TRPC3/6/ 7 channels were identified, and among them, 4m–4p have a potency order of TRPC3 > C7 > C6, with 4n being the most potent with an EC50 of

Preparation of anisotropic particles based on phase separation of prefabricated seeds in polymerizations generally involves multiple process steps. In conventional one-pot dispersion polymerization, only spherical particles are produced. Herein, anisotropic particles with asymmetrical core-shell structure, multiple compartments, and continuously tunable surface roughness and sizes were synthesized by a modified one-pot dispersion polymerization. A mixture of polar solvents, ethylene glycol (EG), and water (6/4, vol.) was used as medium for polymerization of styrene (St). In the presence of ammonium persulfate (APS) and vinyl acetate (VA), divinylbenzene (DVB, 16.1–66.4 %) and (St, 50.3–0 %) were added at 60, 180, and 360 min, respectively. Dense cross-linking was confined to exterior of swollen growing particles, resulting in phase separation and formation of snowman-like particles with coarse, core-shell structured body, and smooth, no or partially cross-linked head. The newly formed compartments were also inhomogeneously cross-linked and their phases separated, producing three and four compartment anisotropic particles with an aspect ratio up to 2.3. Gel content of final particles was less than 75 %. Due to a sequential cross-linking from growing particle to newly formed compartments, reaction stability and particle monodispersity were maintained even when high amounts of DVB were added. Asymmetrical morphologies, structures, sizes, and surface roughness of particles were continuously tuned by varying DVB amount and its start addition time. This one-pot method provides a simple, efficient route for synthesis of anisotropic particles.

Flexible, paper-based graphene and graphene oxides are now emerging as a new class of materials with a variety of applications in electrochemical devices, novel composites, antibacterial agents, separation membranes, and so on. But the tight layer and the poor permeability limit their applications in the fields requiring permeable layers and tunable layer spacing. We demonstrate that the temperature-dependent decomposition reaction of ammonium nitrate can be utilized to modulate the layer spacing of graphene oxide paper and modify its permeability. Unlike the commonly used intercalation method, our strategy enables the layer spacing of the paper to be expanded over large range (123%–20 000%) and avoids the occupation of layer room by guest molecules. Dependent on the expansion amplitude, the papers exhibit a variety of interesting applications, including the highly efficient exclusion of small organic molecules, the separation of ultrathin nanoparticles, and the loading of polar and nonpolar guest molecul...

Transient receptor potential canonical (TRPC) channels play important roles in a broad array of physiological functions and are involved in various diseases. However, due to a lack of potent subtype-specific inhibitors the exact roles of TRPC channels in physiological and pathophysiological conditions have not been elucidated.Using fluorescence membrane potential and Ca(2+) assays and electrophysiological recordings, we characterized new 2-aminobenzimidazole-based small molecule inhibitors of TRPC4 and TRPC5 channels identified from cell-based fluorescence high-throughput screening.The original compound, M084, was a potent inhibitor of both TRPC4 and TRPC5, but was also a weak inhibitor of TRPC3. Structural modifications of the lead compound resulted in the identification of analogues with improved potency and selectivity for TRPC4 and TRPC5 channels. The aminobenzimidazole derivatives rapidly inhibited the TRPC4- and TRPC5-mediated currents when applied from the extracellular side and this inhibition was independent of the mode of activation of these channels. The compounds effectively blocked the plateau potential mediated by TRPC4-containing channels in mouse lateral septal neurons, but did not affect the activity of heterologously expressed TRPA1, TRPM8, TRPV1 or TRPV3 channels or that of the native voltage-gated Na(+) , K(+) and Ca(2) (+) channels in dissociated neurons.The TRPC4/C5-selective inhibitors developed here represent novel and useful pharmaceutical tools for investigation of physiological and pathophysiological functions of TRPC4/C5 channels.

A series of novel 2-aminobenzimidazole derivatives were synthesized under microwave irradiation. Their biological activities were evaluated on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). A number of the 2-aminobenzimidazole derivatives showed good inhibitory activities to AChE and BuChE. Among them, compounds 9, 12 and 13 were found to be >25-fold more selective for BuChE than AChE. No evidence of cytotoxicity was observed by MTT assay in PC12 cells or HepG2 cells exposed to 100 mu M of the compounds. Molecular modeling studies indicate that the benzimidazole moiety of compounds 9, 12 and 13 forms a face-to-face pi-pi stacking interaction in a 'sandwich' form with the indole ring of Trp82 (4.09 angstrom) in the active gorge, and compounds 12 and 13 form a hydrogen bond with His438 at the catalytic site of BuChE. In addition, compounds 12 and 13 fit well into the hydrophobic pocket formed by Ala328, Trp430 and Tyr332 of BuChE. Our data suggest the 2-aminobenzimidazole drugs as promising new selective inhibitors for AChE and BuChE, potentially useful to treat neurodegenerative diseases. (C) 2013 Elsevier Ltd. All rights reserved.