共查询到12条相似文献,搜索用时 15 毫秒
1.
Israel Snchez‐Moreno Virgil Hlaine Nicolas Poupard Franck Charmantray Bertrand Lgeret Laurence Hecquet Eduardo García‐Junceda Roland Wohlgemuth Christine Gurard‐Hlaine Marielle Lemaire 《Advanced Synthesis \u0026amp; Catalysis》2012,354(9):1725-1730
One‐pot multienzymatic reactions have been performed for the synthesis of 1‐deoxy‐D ‐fructose 6‐phosphate, 1,2‐dideoxy‐D ‐arabino‐hept‐3‐ulose 7‐phosphate, D ‐fructose 6‐phosphate and D ‐arabinose 5‐phosphate. The whole synthetic strategy is based on an aldol addition reaction catalysed by fructose‐6‐phosphate aldolase (FSA) as a key step of a three or four enzymes‐catalysed cascade reaction. The four known donors for FSA – dihydroxyacetone (DHA), hydroxyacetone (HA), 1‐hydroxy‐2‐butanone (HB) and glycolaldehyde (GA) – were used with D ‐glyceraldehyde 3‐phosphate as acceptor substrate. The target phosphorylated sugars were obtained in good to excellent yields and high purity. 相似文献
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Xavier Garrabou Jesús Joglar Teodor Parella Ramon Crehuet Jordi Bujons Pere Claps 《Advanced Synthesis \u0026amp; Catalysis》2011,353(1):89-99
The aldol addition of unphosphorylated dihydroxyacetone (DHA) to aldehydes catalyzed by L ‐rhamnulose‐1‐phosphate aldolase (RhuA), a dihydroxyacetone phosphate‐dependent aldolase, is reported. Moreover, a single point mutation in the phosphate binding site of the RhuA wild type, that is, substitution of aspartate for asparagine at position N29, increased by 3‐fold the of aldol addition reactions of DHA to other aldehyde acceptors rather than the natural L ‐lactaldehyde. The RhuA N29D mutant modified the optimum enzyme design for the natural substrate and changed its catalytic properties making the aldolase more versatile to other aldol additions of DHA. 相似文献
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HenryJ. Lamble SylvainF. Royer DavidW. Hough MichaelJ. Danson GarryL. Taylor StevenD. Bull 《Advanced Synthesis \u0026amp; Catalysis》2007,349(6):817-821
A stereochemically promiscuous 2‐keto‐3‐deoxygluconate aldolase has been used as an efficient biocatalyst to catalyse the aldol reaction of pyruvate with C3‐ and C4‐aldoses to afford syn‐ and anti‐3‐deoxy‐2‐ulosonic acids in poor to good de. A continuous flow bioreactor containing immobilised aldolase has been developed that enables gram quantities of C6‐ and C7‐3‐deoxyhept‐2‐ulosonic acids to be produced in an efficient manner. 相似文献
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AnthonyJ. Bellamy AlessandroE. Contini James Padfield Peter Golding MaryF. Mahon 《Propellants, Explosives, Pyrotechnics》2009,34(5):377-384
The ammonium salt of 6‐amino‐2‐hydroxy‐3,5‐dinitropyrazine has been synthesised from 2,6‐dimethoxy‐3,5‐dinitropyrazine and its properties (DSC, crystal structure, impact sensitiveness and thermochemical properties) are compared with the analogous benzene derivative, ammonium 3,5‐diaminopicrate. 相似文献
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Laura López Jana Selent Dr. Raquel Ortega Christian F. Masaguer Dr. Eduardo Domínguez Dr. Filipe Areias Dr. José Brea Dr. María Isabel Loza Dr. Ferran Sanz Dr. Manuel Pastor Dr. 《ChemMedChem》2010,5(8):1300-1317
A series of 37 benzolactam derivatives were synthesized, and their respective affinities for the dopamine D2 and D3 receptors evaluated. The relationships between structures and binding affinities were investigated using both ligand‐based (3D‐QSAR) and receptor‐based methods. The results revealed the importance of diverse structural features in explaining the differences in the observed affinities, such as the location of the benzolactam carbonyl oxygen, or the overall length of the compounds. The optimal values for such ligand properties are slightly different for the D2 and D3 receptors, even though the binding sites present a very high degree of homology. We explain these differences by the presence of a hydrogen bond network in the D2 receptor which is absent in the D3 receptor and limits the dimensions of the binding pocket, causing residues in helix 7 to become less accessible. The implications of these results for the design of more potent and selective benzolactam derivatives are presented and discussed. 相似文献
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Atsushi Toda Kuriko Yamada Shin‐Ichiro Nishimura 《Advanced Synthesis \u0026amp; Catalysis》2002,344(1):61-69
A fusion protein composed of β1,3‐N‐acetyl‐D ‐glucosaminyltransferase (β1,3‐GlcNAcT) from Streptococcus agalactiae type Ia and maltose‐binding protein (MBP) was produced in Escherichia coli as a soluble and highly active form. Although this fusion protein (MBP‐β1,3‐GlcNAcT) did not show any sugar‐elongation activity to some simple low‐molecular weight acceptor substrates such as galactose, Galβ(1→4)Glc (lactose), Galβ(1→4)GlcNAc (N‐acetyllactosamine), Galβ(1→4)GlcNAcβ(1→3)Galβ(1→4)Glc (lacto‐N‐tetraose), and Galβ(1→4)GlcβCer (lactosylceramide, LacCer), the multivalent glycopolymer having LacCer‐mimic branches (LacCer mimic polymer, LacCer primer) was found to be an excellent acceptor substrate for the introduction of a β‐GlcNAc residue at the O‐3 position of the non‐reducing galactose moiety by this engineered enzyme. Subsequently, the polymer having GlcNAcβ(1→3)Galβ(1→4)Glc was subjected to further enzymatic modifications by using recombinant β1,4‐D ‐galactosyltransferase (β1,4‐GalT), α2,3‐sialyltransferase (α2,3‐SiaT), α1,3‐L ‐fucosyltransferase (α1,3‐FucT), and ceramide glycanase (CGase) to afford a biologically important ganglioside; Neu5Aα(2→3)Galβ(1→4)[Fucα(1→3)]GlcNAcβ(1→3)Galβ(1→4)GlcCerα(IV3Neu5Acα,III3Fucα‐nLc4Cer) in 40% yield (4 steps). Interestingly, it was suggested that MBP‐β1,3‐GlcNAcT could also catalyze a glycosylation reaction of the LacCer mimic polymer with N‐acetyl‐D ‐galactosamine served from UDP‐GalNAc to afford a polymer carrying trisaccharide branches, GalNAcβ(1→3)Galβ(1→4)Glc. The versatility of the MBP‐β1,3‐GlcNAcT in the practical synthesis was preliminarily demonstrated by applying this fusion protein as an immobilized biocatalyst displayed on the amylose resin which is known as a solid support showing potent binding‐affinity with MBP. 相似文献
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In this work, we have synthesis nylon‐6/polyethylene oxide (PEO) copolymer system based on feed ratio of PEO (0~ 10 wt %) through condensation polymerization in a pilot scale. The structure of copolymer was confirmed by Fourier transform infrared (FTIR) spectroscopy and verified by 1H nuclear magnetic resonance (1HNMR). The thermal properties were investigated by differential scanning calorimetry (DSC) and indicated both melting temperature (Tm) and cold crystallization temperature (Tc) appearing unapparent decreased while increased PEO content in copolymers. The incorporation of PEO into the nylon‐6 chain reduced its tensile strength, modulus, and heat distortion temperature (HDT). The notched Izod impact strength of and ductility of the copolymers improved significantly as the PEO content was increased. The plasticizing effect was caused by the soft segments from PEO, which increases the mobility of the molecular chain in the copolymers. The results of mechanical tests agree closely with dynamic mechanical analysis (DMA) measurements. A rheological investigation revealed that neat nylon‐6 and its copolymer displayed similar behavior. The crystalline structure was examined by wide‐angle X‐ray diffraction (WAXD). The results demonstrate that the addition of a little PEO altered the crystallization from the α form to the γ form, mainly owing to the breaking parts of the original H‐bonds by the incorporation of ether groups. A mechanism of interaction between the amide and the ether group in nylon‐6/PEO copolymers is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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A novel conjugating polyfluorene bearing N,N‐diethyl‐2‐(4‐phenoxy)‐thioacetamide as side chain was designed for the detection of Hg(II) ions. It was synthesized through postfunctionalization of acetamide‐based polyfluorene derivative. Upon the addition of Hg(II) ions, the thioacetamide groups of this polymer side chains were specifically reacted with Hg(II) ions, leading to this chemodosimeter with higher selectivity for Hg(II) over other metal ions tested under the same conditions. In addition, on the basis of the effect of fluorescent signal amplifications originated from electron transmission along the backbone, this designed conjugated polyfluorene with pendent reactive thioacetamide reached ultra high sensitivity for the detection of mercury ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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Highly enantioselective benzylic hydroxylations of benzene derivatives ( 1–4 ) containing reactive functional groups were achieved for the first time with Pseudomonas monteilii TA‐5 as biocatalyst, giving the corresponding (R)‐benzylic alcohols 5 – 8 in 93–99% ee as the only products. Preparative biotransformations were demonstrated by the biohydroxylation of 1 and 2 with resting cells of P. monteilii TA‐5 to afford (R)‐ 5 in 94% ee and 66% yield and (R)‐ 6 in 94% ee and 56% yield, respectively. The highly enantioselective biohydroxylations represent a simple access to (R)‐benzylic alcohols containing reactive functional groups that are useful pharmaceutical intermediates and versatile chiral building blocks. 相似文献
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Bo Lü Pengbin Li Chunling Fu Liqin Xue Zhenyang Lin Shengming Ma 《Advanced Synthesis \u0026amp; Catalysis》2011,353(1):100-112
A new, readily available monophosphine tetrafluoroborate salt [ L2 ⋅ HBF4 ] was developed for the palladium‐catalyzed amination reaction of aryl chlorides in moderate to high yields with the cheap and easily available potassium hydroxide as the base. The reaction enjoys a wide scope, lower reaction temperatures, shorter reaction times, high yields, and low catalyst loading when compared to some of same amination reactions reported in the literature. Based on a kinetic study, 31P NMR measurements, and DFT calculations, a mechanism involving a 1:1 Pd/L species is proposed. 相似文献