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31.
Engineering the Donor Selectivity of D‐Fructose‐6‐Phosphate Aldolase for Biocatalytic Asymmetric Cross‐Aldol Additions of Glycolaldehyde
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Dr. Anna Szekrenyi Anna Soler Dr. Xavier Garrabou Dr. Christine Guérard‐Hélaine Dr. Teodor Parella Dr. Jesús Joglar Prof. Dr. Marielle Lemaire Dr. Jordi Bujons Prof. Dr. Pere Clapés 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12572-12583
D ‐Fructose‐6‐phosphate aldolase (FSA) is a unique catalyst for asymmetric cross‐aldol additions of glycolaldehyde. A combination of a structure‐guided approach of saturation mutagenesis, site‐directed mutagenesis, and computational modeling was applied to construct a set of FSA variants that improved the catalytic efficiency towards glycolaldehyde dimerization up to 1800‐fold. A combination of mutations in positions L107, A129, and A165 provided a toolbox of FSA variants that expand the synthetic possibilities towards the preparation of aldose‐like carbohydrate compounds. The new FSA variants were applied as highly efficient catalysts for cross‐aldol additions of glycolaldehyde to N‐carbobenzyloxyaminoaldehydes to furnish between 80–98 % aldol adduct under optimized reaction conditions. Donor competition experiments showed high selectivity for glycolaldehyde relative to dihydroxyacetone or hydroxyacetone. These results demonstrate the exceptional malleability of the active site in FSA, which can be remodeled to accept a wide spectrum of donor and acceptor substrates with high efficiency and selectivity. 相似文献
32.
33.
Picart Sébastien Crozet Marielle Canciani Giacomo Davrain Ygor Faure Louis Roudil Danièle 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(2):747-758
Journal of Radioanalytical and Nuclear Chemistry - The accurate determination of plutonium (Pu) mass fraction in nuclear materials is essential to nuclear matter accountancy and international... 相似文献
34.
The use of UV light in copper-catalyzed atom transfer radical addition (ATRA) and cyclization (ATRC) reactions of various (poly)halogenated compounds to highly active alkenes in the presence of AIBN is reported. Radicals generated from photodecomposition of AIBN efficiently regenerated the copper(I) complex at ambient temperature enabling ATRA of CCl(4) and CBr(4) with catalyst loadings as low as 0.05 mol-%. The desired monoadduct was obtained in lower yields in the ATRA of less active halogenated compounds, which was mostly due to incomplete alkene conversions. Ambient temperature ATRA of CCl(4) to various 1,6-dienes followed by sequential ATRC was also performed in the presence of UV light using [Cu(II)(TPMA)Cl][Cl] complex and AIBN. High yields of the 5-exo-trig cyclic product were obtained for all dienes with preferential formation of the cis isomer. 相似文献
35.
A Aliev M Huvé S Colis M Colmont A Dinia O Mentré 《Angewandte Chemie (International ed. in English)》2012,51(37):9393-9397
The modular compound [Mn(3+x) O(7) ][Bi(4) O(4.5-y) ] contains a rare example of true 2D maple-leaf lattice of edge-sharing Mn(3+/4+) . This compound displays a magnetic transition at 210?K without evidence for a Néel ordering, which indicates in-plane 2D antiferromagnetism. 相似文献
36.
Zhenmian Shao Sébastien Saitzek Pascal Roussel Marielle Huvé Rachel Desfeux Olivier Mentré Francis Abraham 《Journal of Crystal Growth》2009,311(16):4134-4141
The effect of the orientation of SrTiO3 (STO) substrates, (1 0 0) or (1 1 0), on the growth of La2Ti2O7 (LTO) and Nd2Ti2O7 (NTO) thin films was investigated. The films were deposited via a sol–gel process coupled to the spin-coating technique. Depending on the substrate orientation, a similar effect was observed on the structural properties for both the LTO and NTO thin films. For (1 1 0)-oriented STO substrate, the films are preferentially (0 0 1) oriented while for (1 0 0)-oriented STO substrates, the orientation is mainly (0 1 2). Those matching appear to be in good agreement with the compatibility between the film/substrate crystal lattices, in relation with the existence of perovskite slabs in Ln2Ti2O7 (Ln=rare earth) compounds. In these latter, a slight disorientation of the (0 1 2) planes with respect to the surface of the substrate was measured. This tilting is even more marked in the case of NTO. The surface morphology was studied by atomic force microscopy. 相似文献
37.
M. Buti C. Vigne C. Montginoul E. Torreilles L. Giral 《Magnetic resonance in chemistry : MRC》1976,8(10):505-507
We report an analysis of the europium-shifted n.m.r. spectrum of 3-(2′,4′-dimethylphenyl)-1H,3H-quinazoline-2,4-dione and the resonance assignment of most of its protons. 相似文献
38.
Dendrimers are highly branched macromolecules which may engage in host-guest interactions, acting as either hosts or guests; this review is specifically concerned with the binding behavior of dendrimers containing single or multiple guest residues interacting with individual, freely diffusing hosts. 相似文献
39.
Hofmeier H Hoogenboom R Wouters ME Schubert US 《Journal of the American Chemical Society》2005,127(9):2913-2921
Using a hydroxy-functionalized terpyridine as initiator, a poly(epsilon-caprolactone) containing one terpyridine endgroup was prepared by tin octanoate-catalyzed controlled ring-opening polymerization. The omega-hydroxy group of this polymer was subsequently reacted with an isocyanato-ureidopyrimidinone, resulting for the first time in polymers bearing a metal-coordinating ligand on the one and a hydrogen-bonding unit on the other chain end. Hydrogen-bonded supramolecular dimers were shown to be present in chloroform solution. The subsequent addition of iron(II) ions resulted in the formation of high molecular weight supramolecular polymers with novel properties resulting from the combination of both types of noncovalent interactions in the main chain, as could be shown using capillary viscosimetry and rheometry. 相似文献
40.
Gaucher B Rouquayrol M Roche D Greiner J Aubertin AM Vierling P 《Organic & biomolecular chemistry》2004,2(3):345-357
With the aim of improving the pharmacological properties of current protease inhibitors (PIs), the synthesis of various acyl and carbamate amino acid- or diglyceride-containing prodrugs derived from saquinavir, indinavir and nelfinavir, their in vitro stability with respect to hydrolysis and their anti-HIV activity in CEM-SS and MT4 cells have been investigated. l-Leucine (Leu) and l-phenylalanine (Phe) were connected through their carboxyl to the PIs while l-tyrosine (Tyr) was conjugated through its aromatic hydroxyl via various spacer units. Hydrolysis of the prodrug with liberation of the active free drug was crucial for antiviral activity. The Leu- and Phe-PI prodrugs released the active free drug very rapidly (half-lives of hydrolysis in buffer at 37 degree C of 3-4 h). The Tyr-PI conjugates with a -C(O)(CH(2))(4)- linker exhibited half-lives in the 40-70 h range and antiviral activities in the 21-325 nM range (from 2 to 22 nM for the free PIs). The chemically very stable carbamate "peptidomimetic" Tyr-PI prodrugs (no hydrolysis detected after 7 days in buffer) displayed a very low anti-HIV activity or were even inactive (EC(50) from 2300 nM to >10 microM). A very low antiviral activity was measured for the diglyceride-substituted saquinavir and for all of the disubstituted indinavir and nelfinavir prodrugs. All these prodrugs probably released the active parent PI too slowly under the antiviral assay conditions. These results combined with those from transepithelial transport studies (Rouquayrol et al., Pharm. Res., 2002, 19, 1704-1712) indicate that conjugation of amino acids (through their carboxyl) to the PIs constitutes a most appealing alternative which could improve the intestinal absorption of the PIs and reduce their recognition by efflux carriers. 相似文献