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1.
Biomacromolecules ; 24(1): 462-470, 2023 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-36563405

RESUMO

Sulfated glycosaminoglycans (GAGs) are fundamental constituents of both the cell surface and extracellular matrix. By playing a key role in cell-cell and cell-matrix interactions, GAGs are involved in many physiological and pathological processes. To design GAG mimetics with similar therapeutic potential as the natural ones, the specific structural features, among them sulfate content, sulfation pattern, and chain length, should be considered. In the present study, we describe a sulfation method based on microwave radiation to obtain highly sulfated derivatives as GAG mimetics. The starting low-molecular-weight (LMW) derivative was prepared from the infernan exopolysaccharide, a highly branched naturally slightly sulfated heteropolysaccharide synthesized by the deep-sea hydrothermal vent bacterium Alteromonas infernus. LMW highly sulfated infernan derivatives obtained by conventional heating sulfation have already been shown to display GAG-mimetic properties. Here, the potential of microwave-assisted sulfation versus that of the conventional method to obtain GAG mimetics was explored. Structural analysis by NMR revealed that highly sulfated derivatives from the two methods shared similar structural features, emphasizing that microwave-assisted sulfation with a 12-fold shorter reaction time is as efficient as the classical one.


Assuntos
Glicosaminoglicanos , Micro-Ondas , Glicosaminoglicanos/química , Sulfatos/química , Espectroscopia de Ressonância Magnética , Matriz Extracelular/metabolismo
2.
Org Biomol Chem ; 19(25): 5529-5533, 2021 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-34105582

RESUMO

Promiscuous activity of a glycosyltransferase was exploited to polymerise glucose from UDP-glucose via the generation of ß-1,4-glycosidic linkages. The biocatalyst was incorporated into biocatalytic cascades and chemo-enzymatic strategies to synthesise cello-oligosaccharides with tailored functionalities on a scale suitable for employment in mass spectrometry-based assays. The resulting glycan structures enabled reporting of the activity and selectivity of celluloltic enzymes.


Assuntos
Glicosiltransferases
3.
Org Biomol Chem ; 18(25): 4831-4842, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32608461

RESUMO

Proteoglycans (PGs) are complex macromolecules that are composed of glycosaminoglycan (GAG) chains covalently attached to a core protein through a tetrasaccharide linker. Biosynthesis of PGs is complex and involves a large number of glycosyltranferases. We report herein for the first time the synthesis of a collection of various sulfoforms of the disaccharide GlcA-1,3-ß-d-Gal and trisaccharides GlcNAc-1,4-α-d-GlcA-1,3-ß-d-Gal and GalNAc-1,4-ß-d-GlcA-1,3-ß-d-Gal using a regioselective glycosylation. Preliminary results on the impact of sulfation of these disaccharides upon recombinant chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1) involved in chondroitin sulfate chain initiation is also reported.


Assuntos
Oligossacarídeos/síntese química , Proteoglicanas/química , Glicosilação , Conformação Molecular , Oligossacarídeos/química , Estereoisomerismo
4.
Org Biomol Chem ; 18(16): 3142-3148, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32255449

RESUMO

The human cell surface trisaccharide motifs globotriose and P1 antigen play key roles in infections by pathogenic bacteria, which makes them important synthetic targets as antibacterial agents. Enzymatic strategies to install the terminal α1,4-galactosidic linkage are very attractive but have only been demonstrated for a limited set of analogues. Herein, a new bacterial α1,4 galactosyltransferase from N. weaveri was cloned and produced recombinantly in E. coli BL21 (DE3) cells, followed by investigation of its substrate specificity. We demonstrate that the enzyme can tolerate galactosamine (GalN) and also 6-deoxygalactose and 6-deoxy-6-fluorogalactose as donors, and lactose and N-acetyllactosamine as acceptors, leading directly to analogues of Gb3 and P1 that are valuable chemical probes and showcase how biocatalysis can provide fast access to a number of unnatural carbohydrate analogues.


Assuntos
Galactosídeos/síntese química , Galactosiltransferases/metabolismo , Neisseria/enzimologia , Amino Açúcares/metabolismo , Proteínas de Bactérias , Biocatálise , Clonagem Molecular , Escherichia coli/genética , Galactosamina/metabolismo , Galactosídeos/biossíntese , Galactosiltransferases/isolamento & purificação , Globosídeos/química , Humanos , Lactose/metabolismo , Especificidade por Substrato , Trissacarídeos/química
5.
Org Biomol Chem ; 17(24): 5920-5924, 2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31165848

RESUMO

Utilising a fast and sensitive screening method based on imidazolium-tagged probes, we report unprecedented reversible activity of bacterial ß1,4-galactosyltransferases to catalyse the transgalactosylation from lactose to N-acetylglucosamine to form N-acetyllactosamine in the presence of UDP. The process is demonstrated by the preparative scale synthesis of pNP-ß-LacNAc from lactose using ß1,4-galactosyltransferase NmLgtB-B as the only biocatalyst.


Assuntos
Amino Açúcares/biossíntese , Galactosiltransferases/metabolismo , Lactose/metabolismo , Amino Açúcares/química , Biocatálise , Galactosiltransferases/química , Lactose/química , Estrutura Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo
6.
Nat Commun ; 15(1): 7925, 2024 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-39271664

RESUMO

Glycan-mediated interactions play a crucial role in biology and medicine, influencing signalling, immune responses, and disease pathogenesis. However, the use of glycans in biosensing and diagnostics is limited by cross-reactivity, as certain glycan motifs can be recognised by multiple biologically distinct protein receptors. To address this specificity challenge, we report the enzymatic synthesis of a 150-member library of site-specifically fluorinated Lewisx analogues ('glycofluoroforms') using naturally occurring enzymes and fluorinated monosaccharides. Subsequent incorporation of a subset of these glycans into nanoparticles or a microarray revealed a striking spectrum of distinct binding intensities across different proteins that recognise Lewisx. Notably, we show that for two proteins with unique binding sites for Lewisx, glycofluoroforms exhibited enhanced binding to one protein, whilst reduced binding to the other, with selectivity governed by fluorination patterns. We finally showcase the potential diagnostic utility of this approach in glycofluoroform-mediated bacterial toxin detection by lateral flow.


Assuntos
Polissacarídeos , Polissacarídeos/metabolismo , Polissacarídeos/química , Ligação Proteica , Sítios de Ligação , Humanos , Halogenação , Antígenos CD15/metabolismo , Antígenos CD15/química , Nanopartículas/química
7.
Carbohydr Res ; 489: 107948, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32062397

RESUMO

Rh/Al2O3 can be used as an effective chemo-selective reductive catalyst that combines the mild conditions of catalytic hydrogenation with high selectivity for azide moieties in the presence of other hydrogenolysis labile groups such as benzyl and benzyloxycarbonyl functionalities. The practicality of this strategy is exemplified with a range of azide-containing carbohydrate and amino acid derivatives.


Assuntos
Aminas/síntese química , Azidas/química , Ródio/química , Aminas/química , Configuração de Carboidratos , Catálise , Hidrogenação
8.
Chem Sci ; 12(3): 905-910, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-34163856

RESUMO

Galectins are potential biomarkers and therapeutic targets. However, galectins display broad affinity towards ß-galactosides meaning glycan-based (nano)biosensors lack the required selectivity and affinity. Using a polymer-stabilized nanoparticle biosensing platform, we herein demonstrate that the specificity of immobilised lacto-N-biose towards galectins can be 'turned on/off' by using site-specific glycan fluorination and in some cases reversal of specificity can be achieved. The panel of fluoro-glycans were obtained by a chemoenzymatic approach, exploiting BiGalK and BiGalHexNAcP enzymes from Bifidobacterium infantis which are shown to tolerate fluorinated glycans, introducing structural diversity which would be very laborious by chemical methods alone. These results demonstrate that integrating non-natural, fluorinated glycans into nanomaterials can encode unprecedented selectivity with potential applications in biosensing.

9.
Chem Commun (Camb) ; 56(47): 6408-6411, 2020 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-32390019

RESUMO

The first synthesis of 3-deoxy-3-fluoro-l-fucose is presented, which employs a d- to l-sugar translation strategy, and involves an enzymatic oxidation of 3-deoxy-3-fluoro-l-fucitol. Enzymatic activation (FKP) and glycosylation using an α-1,2 and an α-1,3 fucosyltransferase to obtain two fluorinated trisaccharides demonstrates its potential as a novel versatile chemical probe in glycobiology.


Assuntos
Fucosiltransferases/metabolismo , Glicoconjugados/biossíntese , Trissacarídeos/biossíntese , Fucosiltransferases/química , Glicoconjugados/química , Glicosilação , Halogenação , Conformação Molecular , Oxirredução , Trissacarídeos/química
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