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Sinead E. Milner Maude Brossat Thomas S. Moody Curtis J. Elcoate Simon E. Lawrence Anita R. Maguire 《Tetrahedron: Asymmetry》2010,21(8):1011-1016
The kinetic bioresolution of 2-nitrocyclohexanol 1 was investigated by screening a range of hydrolases both for enantioselective transesterification and for enantioselective hydrolysis of the corresponding acetate. By appropriate choice of biocatalyst and conditions, both enantiomers of cis and trans 2-nitrocyclohexanol 1 can be accessed in enantiopure form. 相似文献
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Bel R Behnia K Proust C van der Linden P Maude D Vedeneev SI 《Physical review letters》2004,92(17):177003
We present a study of heat and charge transport in Bi(2+x)Sr(2-x)CuO(6+delta) focused on the size of the low-temperature linear term of the thermal conductivity at optimal-doping level. In the superconducting state, the magnitude of this term implies a d-wave gap with an amplitude close to what has been reported. In the normal state, recovered by the application of a magnetic field, measurement of this term and residual resistivity yields a Lorenz number L=kappa(N)rho(0)/T=1.3+/-0.2L(0). The departure from the value expected by the Wiedemann-Franz law is thus slightly larger than our estimated experimental resolution. 相似文献
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Maude Le Hellaye Catherine Lefay Thomas P. Davis Martina H. Stenzel Christopher Barner‐Kowollik 《Journal of polymer science. Part A, Polymer chemistry》2008,46(9):3058-3067
The simultaneous ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) and 2‐hydroxyethyl methacrylate (HEMA) polymerization via reversible addition fragmentation chain transfer (RAFT) chemistry and the possible access to graft copolymers with degradable and nondegradable segments is investigated. HEMA and ε‐CL are reacted in the presence of cyanoisopropyl dithiobenzoate (CPDB) and tin(II) 2‐ethylhexanoate (Sn(Oct)2) under typical ROP conditions (T > 100 °C) using toluene as the solvent in order to lead to the graft copolymer PHEMA‐g‐PCL. Graft copolymer formation is evidenced by a combination of size‐exclusion chromatography (SEC) and NMR analyses as well as confirmed by the hydrolysis of the PCL segments of the copolymer. With targeted copolymers containing at least 10% weight of PHEMA and relatively small PHEMA backbones (ca. 5,000–10,000 g mol?1) the copolymer grafting density is higher than 90%. The ratio of free HEMA‐PCL homopolymer produced during the “one‐step” process was found to depend on the HEMA concentration, as well as the half‐life time of the radical initiator used. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3058–3067, 2008 相似文献
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Ropartz D Bodet PE Przybylski C Gonnet F Daniel R Fer M Helbert W Bertrand D Rogniaux H 《Rapid communications in mass spectrometry : RCM》2011,25(14):2059-2070
Compared to other analytical methods, matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) presents several unique advantages for the structural characterization of degradation products of carbohydrates. Our final goal is to implement this technique as a high-throughput platform, with the aim of exploring natural bio-diversity to discover new carbohydrate depolymerizing enzymes. In this approach, a variety of carbohydrates will be used as enzymes substrates and MALDI-MS will be employed to monitor the oligosaccharides produced. One drawback of MALDI, however, is that the choice of the matrix is largely dependent on the chemical properties of the analyte. In this context, our objective in the present work was to find the smallest set of MALDI matrices able to detect chemically heterogeneous oligosaccharides. This was done through the performance evaluation of more than 40 MALDI matrices preparations. Homogeneity of analyte-matrix deposits was considered as a critical feature, especially since the final objective is to fully automate the analyses. Evaluation of the matrices was done by means of a rigorous statistical approach. Amongst all tested compounds, our work proposes the use of the DHB/DMA ionic matrix as the most generic matrix, for rapid detection of a variety of polysaccharides including neutral, anionic, methylated, sulfated, and acetylated compounds. The selected matrices were then used to screen crude bacterial incubation media for the detection of enzymatic degradation products. 相似文献
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Treatment of α-chloro-δ-(trimethylsilyloxy)ketimines, obtained by regiospecific alkylation of α-chloroketimines with 3-bromo-1-(trimethylsilyloxy)propane, with bases and nucleophiles leads to a variety of oxygen-containing heterocycles, including tetrahydrofurans and tetrahydropyrans. 相似文献
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Replacement of Water Molecules in a Phosphate Binding Site by Furanoside‐Appended lin‐Benzoguanine Ligands of tRNA‐Guanine Transglycosylase (TGT)
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Dr. Luzi J. Barandun Frederik R. Ehrmann Daniel Zimmerli Dr. Florian Immekus Maude Giroud Claudio Grünenfelder Dr. W. Bernd Schweizer Dr. Bruno Bernet Michael Betz Prof. Dr. Andreas Heine Prof. Dr. Gerhard Klebe Prof. Dr. François Diederich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):126-135
The enzyme tRNA‐guanine transglycosylase has been identified as a drug target for the foodborne illness shigellosis. A key challenge in structure‐based design for this enzyme is the filling of the polar ribose‐34 pocket. Herein, we describe a novel series of ligands consisting of furanoside‐appended lin‐benzoguanines. They were designed to replace a conserved water cluster and differ by the functional groups at C(2) and C(3) of the furanosyl moiety being either OH or OMe. The unfavorable desolvation of Asp102 and Asp280, which are located close to the ribose‐34 pocket, had a significant impact on binding affinity. While the enzyme has tRNA as its natural substrate, X‐ray co‐crystal structures revealed that the furanosyl moieties of the ligands are not accommodated in the tRNA ribose‐34 site, but at the location of the adjacent phosphate group. A remarkable similarity of the position of the oxygen atoms in these two structures suggests furanosides as a potential phosphate isoster. 相似文献