Research Interests:
Versatile and sensitive continuous colorimetric assays were developed for the high throughput screening of a large collection of amine-TAs from biodiversity, and allowed the discovery of a set of diverse biocatalysts with high synthetic... more
Versatile and sensitive continuous colorimetric assays were developed for the high throughput screening of a large collection of amine-TAs from biodiversity, and allowed the discovery of a set of diverse biocatalysts with high synthetic potential.
Research Interests:
Research Interests:
Transaminases are efficient tools for the stereoselective conversion of prochiral ketones into valuable chiral amines. Notably, the diversity of naturally occurring α-transaminases offers access to a wide range of L- and D-α-amino acids.... more
Transaminases are efficient tools for the stereoselective conversion of prochiral ketones into valuable chiral amines. Notably, the diversity of naturally occurring α-transaminases offers access to a wide range of L- and D-α-amino acids. We describe here two continuous colorimetric assays for the quantification of transamination activities between a keto acid and a standard donor substrate (L- or D-Glutamic acid or cysteine sulfinic acid). These assays are helpful for kinetic studies as well as for high-throughput screening of enzyme collections.
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Research Interests:
We describe an efficient three‐enzyme, sequential one‐pot cascade reaction where both transketolase substrates are generated in situ in a convergent fashion. The nucleophilic donor substrate hydroxypyruvate was obtained from l‐serine and... more
We describe an efficient three‐enzyme, sequential one‐pot cascade reaction where both transketolase substrates are generated in situ in a convergent fashion. The nucleophilic donor substrate hydroxypyruvate was obtained from l‐serine and pyruvate by a transaminase‐catalyzed reaction. In parallel, three different (2S)‐α‐hydroxylated aldehydes, l‐glyceraldehyde, d‐threose, and l‐erythrose, were generated as electrophilic acceptors from simple achiral compounds glycolaldehyde and formaldehyde by d‐fructose‐6‐phosphate aldolase catalysis. The compatibility of the three enzymes was studied in terms of temperature, enzyme ratio and substrate concentration. The efficiency of the process relied on the irreversibility of the transketolase reaction, driving a shift of the reversible transamination reaction and securing the complete conversion of all substrates. Three valuable (3S,4S)‐ketoses, l‐ribulose, d‐tagatose, and l‐psicose were obtained in good yields with high diastereoselectivity.
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Enzymatic transamination is a useful method for the green and highly enantioselective synthesis of chiral amines and non‐canonical amino acids which are of major importance as intermediates in medicinal chemistry. However, transamination... more
Enzymatic transamination is a useful method for the green and highly enantioselective synthesis of chiral amines and non‐canonical amino acids which are of major importance as intermediates in medicinal chemistry. However, transamination reactions are usually reversible and synthetic applications of transaminases often require the implementation of an equilibrium shift strategy. Herein, we report a highly effective approach using glutamine as smart amine donor. This amino acid is converted upon transamination into 2‐oxoglutaramate which undergoes a fast cyclisation displacing the transamination equilibrium. We have developed a new activity assay in order to identify transaminases from biodiversity able to convert various α‐keto acids into valuable amino acids of l‐ or d‐series in the presence of glutamine as amine donor. Discovered transaminases were then used to prepare in high yield and with high enantioselectivity three amino acids of pharmaceutical importance, homophenylalanine,...
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Naturally rarel-erythro(3S,4S)-ketoses were prepared at high temperatures through a simultaneous two-step enzymatic cascade synthesis with excellent stereoselectivity.
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Research Interests: Biochemistry, Evolutionary Biology, Chemistry, Medicinal Chemistry, Molecular Biology, and 15 moreComputational Biology, Biotechnology, Cancer, Cell Biology, Medicine, Humans, EC, Animals, Metabotropic Glutamate Receptors, Journal Article, Ec, Glutamic Acid, Molecular Structure, Agonist, and Glutamate Receptor
In the course of a project devoted to the stereoselective synthesis of non-proteinogenic α-amino acids using α-transaminases (α-TA), we report the design and optimization of generic high-throughput continuous assays for the screening of... more
In the course of a project devoted to the stereoselective synthesis of non-proteinogenic α-amino acids using α-transaminases (α-TA), we report the design and optimization of generic high-throughput continuous assays for the screening of α-TA libraries. These assays are based on the use of L- or D-cysteine sulfinic acid (CSA) as irreversible amino donor and subsequent sulfite titration by colorimetry. The assays' quality was assessed under screening conditions. Hit selection thresholds were accurately determined for every couple of substrates and a library of 232 putative transaminases expressed in Escherichia coli host cells was screened. The reported high throughput screening assays proved very sensitive allowing the detection with high confidence of activities as low as 10 μU (i.e., 0.01 nmol substrate converted per min). The assays were also evidenced to be stereochemically discriminant since L-CSA and D-CSA allowed the exclusive detection of L-TA and D-TA, respectively. Thes...
Research Interests:
Research Interests:
Aminotransferases are key enzymes of the metabolism of proteinogenic amino acids. These ubiquitous biocatalysts show high specific activities and relaxed substrate specificities making them valuable tools for the stereoselective synthesis... more
Aminotransferases are key enzymes of the metabolism of proteinogenic amino acids. These ubiquitous biocatalysts show high specific activities and relaxed substrate specificities making them valuable tools for the stereoselective synthesis of unnatural amino acids. We describe here the application of aspartate aminotransferase and branched chain aminotransferase from E. coli for the synthesis of various glutamate analogues, molecules of particular interest regarding the neuroactive properties of glutamic acid.
Research Interests:
Research Interests: Magnetic Resonance Imaging, Biology, Immunohistochemistry, Medicine, Hippocampus, and 14 moreBrain, Cerebral Cortex, Mice, Animals, Male, Astrocyte, Central Nervous System, Astrocytes, Herbicides, Glutamine, Glial Fibrillary Acidic Protein, Glutamine Synthetase, Glufosinate, and Pharmacology and pharmaceutical sciences
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1. Prog Biophys Mol Biol. 1995;63(3):301-40. Class I aldolases: substrate specificity, mechanism, inhibitors and structural aspects. Gefflaut T, Blonski C, Perie J, Willson M. Groupe de Chimie Organique Biologique, URA CNRS 470 Université... more
1. Prog Biophys Mol Biol. 1995;63(3):301-40. Class I aldolases: substrate specificity, mechanism, inhibitors and structural aspects. Gefflaut T, Blonski C, Perie J, Willson M. Groupe de Chimie Organique Biologique, URA CNRS 470 Université Paul Sabatier, Toulouse, France. ...
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The synthesis of two enantiomerically pure iminosugars, analogues of 1-L-deoxynojirimycin (l-DNJ) and 1-D-deoxymannojirimycin (DMJ), was achieved using cyclic sulfate substituted isoxazoline derivatives. The piperidine ring was formed via... more
The synthesis of two enantiomerically pure iminosugars, analogues of 1-L-deoxynojirimycin (l-DNJ) and 1-D-deoxymannojirimycin (DMJ), was achieved using cyclic sulfate substituted isoxazoline derivatives. The piperidine ring was formed via the reduction of an isoxazoline into an amine which underwent a spontaneous intramolecular cyclization by reaction with the cyclic sulfate moiety. The nucleophilic attack of these two trisubstituted piperidines and morpholine on L- and D-erythritol-1,3-cyclic sulfates gave six new nitrogen analogues of salacinol. The inhibitory properties of the synthesized salacinol analogues were evaluated on several commercial glycosidases.
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Research Interests: Chemistry, Organic Chemistry, Medicinal Chemistry, Medicine, Cell line, and 15 moreGlutamate, Humans, Animals, Stereochemistry, Myocardium, Swine, Medicinal, Transporter, Structure activity Relationship, Aspartate Aminotransferases, Glutamate Transporter, Enantiomer, Glutamate Receptor, Pharmacology and pharmaceutical sciences, and stereoisomerism
Research Interests: Chemistry, Organic Chemistry, Medicinal Chemistry, Catalysis, Medicine, and 15 moreMacromolecular X-Ray Crystallography, Brain, Humans, Animals, Rats, Radioligand Assay, Structure activity Relationship, Ligands, Aspartate Aminotransferases, Glutamic Acid, Molecular Structure, Glutamate Receptor, Pharmacology and pharmaceutical sciences, In Vitro Techniques, and stereoisomerism
Research Interests: Biochemistry, Chemistry, Organic Chemistry, Medicinal Chemistry, Magnetic Resonance Spectroscopy, and 10 moreMedicine, Cell line, Humans, Enzyme, Liquid Chromatography / Electrospray Ionization Mass Spectrometry, Medicinal, Transporter, Amino Acid Profile, Pharmacology and pharmaceutical sciences, and stereoisomerism
The conserved residue Asp477 in yeast transketolase is located in the substrate channel of the enzyme and forms a hydrogen bond with the C2‐hydroxyl group of the acceptor substrate. The significance of this interaction for the recognition... more
The conserved residue Asp477 in yeast transketolase is located in the substrate channel of the enzyme and forms a hydrogen bond with the C2‐hydroxyl group of the acceptor substrate. The significance of this interaction for the recognition of the preferred acceptor substrates, d‐α‐hydroxyaldehydes was investigated by site‐directed mutagenesis. In the wild‐type enzyme the k cat/K M values are by three to four orders of magnitude lower for 2‐deoxyaldoses or substrates with l‐configuration at the C2‐atom. In the Asp477Ala mutant, the k cat/K M values for d‐α‐hydroxyaldehydes are decreased by a thousandfold, while the k cat/K M values for substrates with l‐configuration or 2‐deoxyaldoses are similar to wild‐type enzyme. These results indicate that Asp477 is involved in determining the enantioselectivity of transketolase.
Research Interests:
Research Interests: Chemistry, Kinetics, Biology, Medicine, Glutamate, and 15 moreIonotropic Receptor, Glutamate receptors, Animals, Propionic Acid, Central Nervous System, Radioligand Assay, Molecular Conformation, Ligands, Glutamic Acid, Molecular Structure, Glutamate Receptor, Binding affinity, Kainic acid, NMDA receptor, and Pharmacology and pharmaceutical sciences
Various dihydroxyacetone-phosphate (DHAP) analogues bearing an aromatic ring or β-dicarbonyl structures were synthesized. Their capacity to form a stabilized iminium ion or conjugated enamine in the reaction catalyzed by rabbit muscle... more
Various dihydroxyacetone-phosphate (DHAP) analogues bearing an aromatic ring or β-dicarbonyl structures were synthesized. Their capacity to form a stabilized iminium ion or conjugated enamine in the reaction catalyzed by rabbit muscle aldolase (EC 4.1.2.13) were investigated by enzymatic kinetics and UV difference spectroscopic techniques. Whereas the aromatic derivative led to competitive inhibition without detectable iminium ion formation, slow reversible inhibitions