25 research outputs found
Syntèse chimio-enzymatique de glycoconjugués furanosidiques immuno-stimulants
Hexofuranoses are absent from mammals, but are present in numerous microorganisms, often highly pathogenic. This makes them very attractive targets for the development of new antimicrobial drugs. As an alternative to organic synthesis, the use of enzymes has been increasingly appreciated in the synthesis of glycoconjugates. Here we report the use of alpha-l-Arabinofuranosidase Araf51 for the synthesis of furanosyl-containing glycoconjugates. This enzyme was really efficient in catalysing oligomerisations of l-arabinofuranoside and d-galactofuranoside up to the formation of pentasaccharides, as well as in the synthesis of furanosides containing structurally modified d-galactofuranosides and pyrano-furano disaccharides. Many of synthesised compounds represented biologically relevant structures found in some clinically important pathogens. Biological tests proved that these neofuranosides have robust immunostimulatory properties and can become a potentially very useful new type of adjuvants.Les hexofuranoses sont absents chez les mammifères, mais sont présents dans de nombreux micro-organismes souvent hautement pathogènes, ce qui les rend très intéressants pour le développement de nouveaux médicaments antimicrobiens. Les enzymes sont de plus en plus souvent utilisées pour la synthèse de glycoconjugués comme une alternative à la synthèse organique. Dans ce travail, nous présentons l'utilisation d alpha-l-Arabinofuranosidase Araf51 pour la synthèse de glycoconjugés contenant des unités furanosidiques. Cette enzyme s est révélée très efficace pour catalyser les oligomérisations des dérivés du l-arabinofuranoside et ceux du d-galactofuranoside jusqu'à la formation de pentasaccharides, ainsi que dans la synthèse de furanosides contenant des motifs structuralement modifiés du d-galactofuranose et des disaccharides de type pyrano-furano. Un grand nombre de composés synthétisés présentent des structures d intérêt biologique que l on retrouve dans certains agents pathogènes. Les essais biologiques ont montré que ces néofuranosides ont de fortes propriétés immunostimulatrices et peuvent potentiellement constituer un nouveau type d adjuvants.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF
One step enzymatic process for producing alkyl furanosides
publication date: 2013-10-31; filing date: 2013-04-1
Phenotype-Based Isolation of Antigen-Specific CD4+ T Cells in Autoimmunity: A Study of Celiac Disease
The pathogenic immune response in celiac disease (CeD) is orchestrated by phenotypically distinct CD4+ T cells that recognize gluten epitopes in the context of disease-associated HLA-DQ allotypes. Cells with the same distinct phenotype, but with elusive specificities, are increased across multiple autoimmune conditions. Here, whether sorting of T cells based on their distinct phenotype (Tphe cells) yields gluten-reactive cells in CeD is tested. The method′s efficiency is benchmarked by parallel isolation of gluten-reactive T cells (Ttet cells), using HLA-DQ:gluten peptide tetramers. From gut biopsies of 12 untreated HLA-DQ2.5+ CeD patients, Ttet+/Tphe+, Ttet−/Tphe+, and Ttet−/Tphe− cells are sorted for single-cell T-cell receptor (TCR)-sequencing (n = 8) and T-cell clone (TCC)-generation (n = 5). The generated TCCs are TCR sequenced and tested for their reactivity against deamidated gluten. Gluten-reactivity is observed in 91.2% of Ttet+/Tphe+ TCCs, 65.3% of Ttet−/Tphe+ TCCs and 0% of Ttet−/Tphe− TCCs. TCR sequencing reveals clonal expansion and sequence sharing across patients, features reflecting antigen-driven responses. The feasibility to isolate antigen-specific CD4+ T cells by the sole use of phenotypic markers in CeD outlines a potential avenue for characterizing disease-driving CD4+ T cells in autoimmune conditions
Affinity Chromatography as a Method of Studying the Mechanism of Action of Plant Oxysterols
peer reviewe
Specific and non-specific enzymes for furanosyl-containing conjugates: biosynthesis, metabolism, and chemo-enzymatic synthesis.
There is no doubt now that the synthesis of compounds of varying complexity such as saccharides and derivatives thereof continuously grows with enzymatic methods. This review focuses on recent basic knowledge on enzymes specifically involved in the biosynthesis and degradation of furanosyl-containing polysaccharides and conjugates. Moreover, and when possible, biocatalyzed approaches, alternative to standard synthesis, will be detailed in order to strengthen the high potential of these biocatalysts to go further with the preparation of rare furanosides. Interesting results will be also proposed with chemo-enzymatic processes based on nonfuranosyl-specific enzymes
Natural glycans and glycoconjugates as immunomodulating agents.
International audienc
Enzymatic synthesis of oligo-D-galactofuranosides and l-arabinofuranosides: from molecular dynamics to immunological assays.
D-Galactofuranosyl-containing conjugates are ubiquitous in many pathogenic microorganisms, but completely absent from mammals. As they may constitute interesting pharmacophores, recent works have been dedicated to their preparation. Besides well-reported chemical procedures, enzymatic approaches are still limited, mainly due to the lack of the corresponding biocatalysts. Based on the similarity between chemical structures, the arabinofuranosyl hydrolase Araf51 from Clostridium thermocellum was expected to recognize both the L-Araf motif and its D-Galf analogue. Molecular dynamics and STD-NMR were firstly used to confirm this hypothesis and increase our knowledge of the active site. Interestingly, this arabinofuranosidase was not only able to hydrolyze galactosyl derivatives, but was also really efficient in catalyzing oligomerisations using p-nitrophenyl furanosides as donors. The structures of the products obtained were determined using mass spectrometry and NMR. Amongst them, all the possible regioisomers of di-arabino and -galactofuranosides were synthesized, and the ratio of each regioisomer was easily tuned with respect to the reaction time. Especially, the galactofuranobioside displaying the biologically relevant sequence beta-D-Galf-(1,6)-beta-D-Galf was enzymatically prepared for the first time. All fractions going from di- to penta-arabino- and galactofuranosides were tested for their ability in eliciting the production of TNF-alpha. Interesting immunological properties were observed with arabinofuranosides as short as three sugar residues