Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 33
Filtrar
1.
Glycobiology ; 34(3)2024 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-38227775

RESUMO

CD14 is an innate immune receptor that senses pathogen-associated molecular patterns, such as lipopolysaccharide, to activate the innate immune response. Although CD14 is known to be glycosylated, detailed understanding about the structural and functional significance of this modification is still missing. Herein, an NMR and MS-based study, assisted by MD simulations, has provided a 3D-structural model of glycosylated CD14. Our results reveal the existence of a key N-glycosylation site at Asn282 that exclusively contains unprocessed oligomannnose N-glycans that perfectly fit the concave cavity of the bent-solenoid shaped protein. This site is not accessible to glycosidases and is fundamental for protein folding and secretion. A second N-site at Asn151 displays mostly complex N-glycans, with the typical terminal epitopes of the host cell-line expression system (i.e. ßGal, α2,3 and α2,6 sialylated ßGal, here), but also particularities, such as the lack of core fucosylation. The glycan at this site points outside the protein surface, resulting in N-glycoforms fully exposed and available for interactions with lectins. In fact, NMR experiments show that galectin-4, proposed as a binder of CD14 on monocytes to induce their differentiation into macrophages-like cells, interacts in vitro with CD14 through the recognition of the terminal glycoepitopes on Asn151. This work provides key information about CD14 glycosylation, which helps to better understand its functional roles and significance. Although protein glycosylation is known to be dynamic and influenced by many factors, some of the features found herein (presence of unprocessed N-glycans and lack of core Fuc) are likely to be protein specific.


Assuntos
Lectinas , Polissacarídeos , Glicosilação , Polissacarídeos/química , Lectinas/metabolismo , Linhagem Celular , Lipopolissacarídeos/metabolismo
2.
Chem Soc Rev ; 52(5): 1591-1613, 2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36753338

RESUMO

Nuclear Magnetic Resonance (NMR) has been widely employed to assess diverse features of glycan-protein molecular recognition events. Different types of qualitative and quantitative information at different degrees of resolution and complexity can be extracted from the proper application of the available NMR-techniques. In fact, affinity, structural, kinetic, conformational, and dynamic characteristics of the binding process are available. Nevertheless, except in particular cases, the affinity of lectin-sugar interactions is weak, mostly at the low mM range. This feature is overcome in biological processes by using multivalency, thus augmenting the strength of the binding. However, the application of NMR methods to monitor multivalent lectin-glycan interactions is intrinsically challenging. It is well known that when large macromolecular complexes are formed, the NMR signals disappear from the NMR spectrum, due to the existence of fast transverse relaxation, related to the large size and exchange features. Indeed, at the heart of the molecular recognition event, the associated free-bound chemical exchange process for both partners takes place in a particular timescale. Thus, these factors have to be considered and overcome. In this review article, we have distinguished, in a subjective manner, the existence of multivalent presentations in the glycan or in the lectin. From the glycan perspective, we have also considered whether multiple epitopes of a given ligand are presented in the same linear chain of a saccharide (i.e., poly-LacNAc oligosaccharides) or decorating different arms of a multiantennae scaffold, either natural (as in multiantennae N-glycans) or synthetic (of dendrimer or polymer nature). From the lectin perspective, the presence of an individual binding site at every monomer of a multimeric lectin may also have key consequences for the binding event at different levels of complexity.


Assuntos
Carboidratos , Oligossacarídeos , Carboidratos/química , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Polissacarídeos/química , Espectroscopia de Ressonância Magnética , Lectinas
3.
J Am Chem Soc ; 145(25): 14052-14063, 2023 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-37310804

RESUMO

Zwitterionic polysaccharides (ZPSs) are exceptional carbohydrates, carrying both positively charged amine groups and negatively charged carboxylates, that can be loaded onto MHC-II molecules to activate T cells. It remains enigmatic, however, how these polysaccharides bind to these receptors, and to understand the structural features responsible for this "peptide-like" behavior, well-defined ZPS fragments are required in sufficient quantity and quality. We here present the first total synthesis of Bacteroides fragilis PS A1 fragments encompassing up to 12 monosaccharides, representing three repeating units. Key to our successful syntheses has been the incorporation of a C-3,C-6-silylidene-bridged "ring-inverted" galactosamine building block that was designed to act as an apt nucleophile as well as a stereoselective glycosyl donor. Our stereoselective synthesis route is further characterized by a unique protecting group strategy, built on base-labile protecting groups, which has allowed the incorporation of an orthogonal alkyne functionalization handle. Detailed structural studies have revealed that the assembled oligosaccharides take up a bent structure, which translates into a left-handed helix for larger PS A1 polysaccharides, presenting the key positively charged amino groups to the outside of the helix. The availability of the fragments and the insight into their secondary structure will enable detailed interaction studies with binding proteins to unravel the mode of action of these unique oligosaccharides at the atomic level.


Assuntos
Bacteroides fragilis , Polissacarídeos Bacterianos , Polissacarídeos Bacterianos/química , Bacteroides fragilis/química , Oligossacarídeos , Monossacarídeos , Linfócitos T
4.
Chemistry ; 29(18): e202203591, 2023 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-36597924

RESUMO

In recent years, glycomics have shown how pervasive the role of carbohydrates in biological systems is and how chemical tools are essential to investigate glycan function and modulate carbohydrate-mediated processes. Biomimetic receptors for carbohydrates can carry out this task but, although significant affinities and selectivities toward simple saccharides have been achieved, targeting complex glycoconjugates remains a goal yet unattained. In this work we report the unprecedented recognition of a complex biantennary sialylglycopeptide (SGP) by a tweezers-shaped biomimetic receptor, which selectively binds to the core GlcNAc2 disaccharide of the N-glycan with an affinity of 170 µM. Because of the simple structure and the remarkable binding ability, this biomimetic receptor can represent a versatile tool for glycoscience, opening the way to useful applications.


Assuntos
Biomimética , Dissacarídeos , Polissacarídeos/química , Carboidratos/química , Glicômica
5.
Angew Chem Int Ed Engl ; 62(41): e202309838, 2023 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-37555536

RESUMO

Herpes simplex virus (HSV-1) employs heparan sulfate (HS) as receptor for cell attachment and entry. During late-stage infection, the virus induces the upregulation of human heparanase (Hpse) to remove cell surface HS allowing viral spread. We hypothesized that inhibition of Hpse will prevent viral release thereby representing a new therapeutic strategy for HSV-1. A range of HS-oligosaccharides was prepared to examine the importance of chain length and 2-O-sulfation of iduronic moieties for Hpse inhibition. It was found that hexa- and octasaccharides potently inhibited the enzyme and that 2-O-sulfation of iduronic acid is tolerated. Computational studies provided a rationale for the observed structure-activity relationship. Treatment of human corneal epithelial cells (HCEs) infected with HSV-1 with the hexa- and octasaccharide blocked viral induced shedding of HS which significantly reduced spread of virions. The compounds also inhibited migration and proliferation of immortalized HCEs thereby providing additional therapeutic properties.


Assuntos
Glucuronidase , Herpes Simples , Herpesvirus Humano 1 , Humanos , Glucuronidase/antagonistas & inibidores , Glucuronidase/metabolismo , Heparitina Sulfato/farmacologia , Herpes Simples/enzimologia , Herpes Simples/virologia , Herpesvirus Humano 1/metabolismo , Oligossacarídeos/farmacologia , Oligossacarídeos/metabolismo
6.
J Am Chem Soc ; 144(1): 424-435, 2022 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-34967208

RESUMO

O-Acetylation is a common modification of sialic acids that can occur at carbons 4-, 7-, 8-, and/or 9. Acetylated sialosides are employed as receptors by several betacoronaviruses and toroviruses, and by influenza C and D viruses. The molecular basis by which these viruses recognize specific O-acetylated sialosides is poorly understood, and it is unknown how viruses have evolved to recognize specific O-acetylated sialosides expressed by their host. Here, we describe a chemoenzymatic approach that can readily provide sialoglycan analogues in which acetyl esters at C4 and/or C7 are replaced by stabilizing acetamide moieties. The analogues and their natural counterparts were used to examine the ligand requirements of the lectin domain of coronaviral hemagglutinin-esterases (HEs). It revealed that HEs from viruses targeting different host species exhibit different requirements for O-acetylation. It also showed that ester-to-amide perturbation results in decreased or loss of binding. STD NMR and molecular modeling of the complexes of the HE of BCoV with the acetamido analogues and natural counterparts revealed that binding is governed by the complementarity between the acetyl moieties of the sialosides and the hydrophobic patches of the lectin. The precise spatial arrangement of these elements is important, and an ester-to-amide perturbation results in substantial loss of binding. Molecular Dynamics simulations with HEs from coronaviruses infecting other species indicate that these viruses have adapted their HE specificity by the incorporation of hydrophobic or hydrophilic elements to modulate acetyl ester recognition.


Assuntos
Coronavirus
7.
Angew Chem Int Ed Engl ; 61(18): e202201432, 2022 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-35191576

RESUMO

The interaction of the SARS CoV2 spike glycoprotein with two sialic acid-containing trisaccharides (α2,3 and α2,6 sialyl N-acetyllactosamine) has been demonstrated by NMR. The NMR-based distinction between the signals of those sialic acids in the glycans covalently attached to the spike protein and those belonging to the exogenous α2,3 and α2,6 sialyl N-acetyllactosamine ligands has been achieved by synthesizing uniformly 13 C-labelled trisaccharides at the sialic acid and galactose moieties. STD-1 H,13 C-HSQC NMR experiments elegantly demonstrate the direct interaction of the sialic acid residues of both trisaccharides with additional participation of the galactose moieties, especially for the α2,3-linked analogue. Additional experiments with the spike protein in the presence of a specific antibody for the N-terminal domain and with the isolated receptor binding and N-terminal domains of the spike protein unambiguously show that the sialic acid binding site is located at the N-terminal domain.


Assuntos
COVID-19 , Glicoproteína da Espícula de Coronavírus , Sítios de Ligação , Galactose , Humanos , Ácido N-Acetilneuramínico/química , SARS-CoV-2 , Ácidos Siálicos/química , Glicoproteína da Espícula de Coronavírus/química , Trissacarídeos
8.
Chemistry ; 27(6): 2149-2154, 2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33047840

RESUMO

Glycans possess unparalleled structural complexity arising from chemically similar monosaccharide building blocks, configurations of anomeric linkages and different branching patterns, potentially giving rise to many isomers. This level of complexity is one of the main reasons that identification of exact glycan structures in biological samples still lags behind that of other biomolecules. Here, we introduce a methodology to identify isomeric N-glycans by determining gas phase conformer distributions (CDs) by measuring arrival time distributions (ATDs) using drift-tube ion mobility spectrometry-mass spectrometry. Key to the approach is the use of a range of well-defined synthetic glycans that made it possible to investigate conformer distributions in the gas phase of isomeric glycans in a systematic manner. In addition, we have computed CD fingerprints by molecular dynamics (MD) simulation, which compared well with experimentally determined CDs. It supports that ATDs resemble conformational populations in the gas phase and offer the prospect that such an approach can contribute to generating a library of CCS distributions (CCSDs) for structure identification.

9.
Chem Soc Rev ; 49(12): 3863-3888, 2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32520059

RESUMO

This review provides an extensive summary of the effects of carbohydrate fluorination with regard to changes in physical, chemical and biological properties with respect to regular saccharides. The specific structural, conformational, stability, reactivity and interaction features of fluorinated sugars are described, as well as their applications as probes and in chemical biology.


Assuntos
Carboidratos/química , Sondas Moleculares/química , Animais , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Glicosídeos/química , Halogenação , Humanos , Neoplasias/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Vacinas Sintéticas/química , Vacinas Sintéticas/imunologia
10.
Int J Mol Sci ; 22(4)2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33670179

RESUMO

Fumarylacetoacetate hydrolase (FAH) is the fifth enzyme in the tyrosine catabolism pathway. A deficiency in human FAH leads to hereditary tyrosinemia type I (HT1), an autosomal recessive disorder that results in the accumulation of toxic metabolites such as succinylacetone, maleylacetoacetate, and fumarylacetoacetate in the liver and kidney, among other tissues. The disease is severe and, when untreated, it can lead to death. A low tyrosine diet combined with the herbicidal nitisinone constitutes the only available therapy, but this treatment is not devoid of secondary effects and long-term complications. In this study, we targeted FAH for the first-time to discover new chemical modulators that act as pharmacological chaperones, directly associating with this enzyme. After screening several thousand compounds and subsequent chemical redesign, we found a set of reversible inhibitors that associate with FAH close to the active site and stabilize the (active) dimeric species, as demonstrated by NMR spectroscopy. Importantly, the inhibitors are also able to partially restore the normal phenotype in a newly developed cellular model of HT1.


Assuntos
Sistemas de Liberação de Medicamentos , Inibidores Enzimáticos/farmacologia , Hidrolases/antagonistas & inibidores , Hidrolases/metabolismo , Tirosinemias/tratamento farmacológico , Tirosinemias/enzimologia , Animais , Domínio Catalítico , Inibidores Enzimáticos/química , Células HEK293 , Humanos , Hidrolases/genética , Camundongos , Tirosinemias/genética
11.
Angew Chem Int Ed Engl ; 60(35): 19287-19296, 2021 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-34124805

RESUMO

The importance of multivalency for N-glycan-protein interactions has primarily been studied by attachment of minimal epitopes to artificial multivalent scaffold and not in the context of multi-antennary glycans. N-glycans can be modified by bisecting GlcNAc, core xylosides and fucosides, and extended N-acetyl lactosamine moieties. The impact of such modifications on glycan recognition are also not well understood. We describe here a chemoenzymatic methodology that can provide N-glycans expressed by the parasitic worm S. mansoni having unique epitopes at each antenna and containing core xyloside. NMR, computational and electron microscopy were employed to investigate recognition of the glycans by the human lectin DC-SIGN. It revealed that core xyloside does not influence terminal epitope recognition. The multi-antennary glycans bound with higher affinity to DC-SIGN compared to mono-valent counterparts, which was attributed to proximity-induced effective concentration. The multi-antennary glycans cross-linked DC-SIGN into a dense network, which likely is relevant for antigen uptake and intracellular routing.


Assuntos
Epitopos/química , Lectinas/análise , Polissacarídeos/química , Schistosoma mansoni/química , Animais , Humanos , Polissacarídeos/síntese química
12.
J Biol Chem ; 294(14): 5688-5699, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30737276

RESUMO

The chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) is a large dsDNA virus that infects the microalga Chlorella variabilis NC64A. Unlike most other viruses, PBCV-1 encodes most, if not all, of the machinery required to glycosylate its major capsid protein (MCP). The structures of the four N-linked glycans from the PBCV-1 MCP consist of nonasaccharides, and similar glycans are not found elsewhere in the three domains of life. Here, we identified the roles of three virus-encoded glycosyltransferases (GTs) that have four distinct GT activities in glycan synthesis. Two of the three GTs were previously annotated as GTs, but the third GT was identified in this study. We determined the GT functions by comparing the WT glycan structures from PBCV-1 with those from a set of PBCV-1 spontaneous GT gene mutants resulting in antigenic variants having truncated glycan structures. According to our working model, the virus gene a064r encodes a GT with three domains: domain 1 has a ß-l-rhamnosyltransferase activity, domain 2 has an α-l-rhamnosyltransferase activity, and domain 3 is a methyltransferase that decorates two positions in the terminal α-l-rhamnose (Rha) unit. The a075l gene encodes a ß-xylosyltransferase that attaches the distal d-xylose (Xyl) unit to the l-fucose (Fuc) that is part of the conserved N-glycan core region. Last, gene a071r encodes a GT that is involved in the attachment of a semiconserved element, α-d-Rha, to the same l-Fuc in the core region. Our results uncover GT activities that assemble four of the nine residues of the PBCV-1 MCP N-glycans.


Assuntos
Antígenos Virais/metabolismo , Proteínas do Capsídeo/metabolismo , Chlorella/metabolismo , Glicosiltransferases/metabolismo , Phycodnaviridae/enzimologia , Polissacarídeos/metabolismo , Antígenos Virais/genética , Antígenos Virais/imunologia , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/imunologia , Chlorella/genética , Chlorella/virologia , Glicosiltransferases/genética , Glicosiltransferases/imunologia , Phycodnaviridae/genética , Phycodnaviridae/imunologia , Polissacarídeos/genética , Polissacarídeos/imunologia
13.
Chemistry ; 26(67): 15605-15612, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32957164

RESUMO

The parasitic worm, Schistosoma mansoni, expresses unusual fucosylated glycans in a stage-dependent manner that can be recognized by the human innate immune receptor DC-SIGN, thereby shaping host immune responses. We have developed a synthetic approach for mono- and bis-fucosylated LacdiNAc (LDN-F and LDN-DF, respectively), which are epitopes expressed on glycolipids and glycoproteins of S. mansoni. It is based on the use of monosaccharide building blocks having carefully selected amino-protecting groups, facilitating high yielding and stereoselective glycosylations. The molecular interaction between the synthetic glycans and DC-SIGN was studied by NMR and molecular modeling, which demonstrated that the α1,3-fucoside of LDN-F can coordinate with the Ca2+ -ion of the canonical binding site of DC-SIGN allowing for additional interactions with the underlying LDN backbone. The 1,2-fucoside of LDN-DF can be complexed in a similar manner, however, in this binding mode GlcNAc and GalNAc of the LDN backbone are placed away from the protein surface resulting in a substantially lower binding affinity. Glycan microarray binding studies showed that the avidity and selectivity of binding is greatly enhanced when the glycans are presented multivalently, and in this format Lex and LDN-F gave strong responsiveness, whereas no binding was detected for LDN-DF. The data indicates that S. mansoni has developed a strategy to avoid detection by DC-SIGN in a stage-dependent manner by the addition of a fucoside to a number of its ligands.


Assuntos
Moléculas de Adesão Celular , Lectinas Tipo C , Polissacarídeos , Receptores de Superfície Celular , Schistosoma mansoni , Animais , Moléculas de Adesão Celular/imunologia , Glicosilação , Humanos , Imunidade Inata , Lectinas Tipo C/imunologia , Polissacarídeos/imunologia , Receptores de Superfície Celular/imunologia , Schistosoma mansoni/imunologia
14.
Chemistry ; 24(59): 15761-15765, 2018 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-30276889

RESUMO

Glycan-protein interactions play an important role in a broad range of physiological processes, raising interest to elucidate the structural interplay. Yet, their dynamic nature limits the analysis by crystallography, whereas NMR spectroscopy suffers from the low 1 H dispersion of glycans. Therefore, their sparse fluorination and NMR screening by 1D Saturation Transfer Difference with relay to 19 F (STDreF) was previously proposed to exploit the superior dispersion in 19 F NMR spectroscopy. A new 2D STD-TOCSYreF experiment is presented here that enables comprehensive epitope mapping of fluorinated glycans by combining the spectral resolution of 19 F with the spatial resolution and coverage of 1 H. For an illustration, the 2-deoxy-2-fluoro derivative of the N-glycan core trimannoside was synthesised and its recognition of Pisum sativum agglutinin by either of the two terminal mannose residues was confirmed. Going beyond the crystallographic information, the 2D STD-TOCSYreF spectrum moreover visualised collateral contacts from the branching mannose and allowed to assess the ratio of both co-existing binding modes through the α1,3- (67 %) and α1,6-linked (33 %) terminal mannose moieties.

15.
European J Org Chem ; 2018(33): 4548-4555, 2018 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-30443159

RESUMO

Neisseria meningitidis serogroup A (MenA) is an aerobic diplococcal Gram-negative bacterium responsible for epidemic meningitis disease. Its capsular polysaccharide (CPS) has been identified as the primary virulence factor of MenA. This polysaccharide suffers from chemical lability in water. Thus, the design and synthesis of novel and hydrolytically stable structural analogues of MenA CPS may provide additional tools for the development of therapies against this disease. In this context, the structural features of the natural phosphorylated monomer have been analyzed and compared to those of its carba-analogue, where the endocyclic oxygen has been replaced by a methylene moiety. The lowest energy geometries of the different molecules have been calculated using a combination of quantum mechanical techniques and molecular dynamics simulations. The predicted results have been compared and validated using NMR experiments. The results indicate that the more stable designed glycomimetics may adopt the conformation adopted by the natural monomer, although they display a wider flexibility around the torsional degrees of freedom.

16.
Chemistry ; 23(16): 3957-3965, 2017 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-28124793

RESUMO

We herein propose the use of fluoroacetamide and difluoroacetamide moieties as sensitive tags for the detection of sugar-protein interactions by simple 1 H and/or 19 F NMR spectroscopy methods. In this process, we have chosen the binding of N,N'-diacetyl chitobiose, a ubiquitous disaccharide fragment in glycoproteins, by wheat-germ agglutinin (WGA), a model lectin. By using saturation-transfer difference (STD)-NMR spectroscopy, we experimentally demonstrate that, under solution conditions, the molecule that contained the CHF2 CONH- moiety is the stronger aromatic binder, followed by the analogue with the CH2 FCONH- group and the natural molecule (with the CH3 CONH- fragment). In contrast, the molecule with the CF3 CONH- isoster displayed the weakest intermolecular interaction (one order of magnitude weaker). Because sugar-aromatic CH-π interactions are at the origin of these observations, these results further contribute to the characterization and exploration of these forces and offer an opportunity to use them to unravel complex recognition processes.


Assuntos
Dissacarídeos/metabolismo , Fluoracetatos/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Aglutininas do Germe de Trigo/metabolismo , Dissacarídeos/análise , Fluoracetatos/análise , Halogenação , Análise em Microsséries , Ligação Proteica , Triticum/química , Triticum/metabolismo , Aglutininas do Germe de Trigo/análise
17.
Chemistry ; 21(29): 10513-21, 2015 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-26096911

RESUMO

Sugar function, structure and dynamics are intricately correlated. Ring flexibility is intrinsically related to biological activity; actually plasticity in L-iduronic rings modulates their interactions with biological receptors. However, the access to the experimental values of the energy barriers and free-energy difference for conformer interconversion in water solution has been elusive. Here, a new generation of fluorine-containing glycomimetics is presented. We have applied a combination of organic synthesis, NMR spectroscopy and computational methods to investigate the conformational behaviour of idose- and glucose-like rings. We have used low-temperature NMR spectroscopic experiments to slow down the conformational exchange of the idose-like rings. Under these conditions, the exchange rate becomes slow in the (19) F NMR spectroscopic chemical shift timescale and allows shedding light on the thermodynamic and kinetic features of the equilibrium. Despite the minimal structural differences between these compounds, a remarkable difference in their dynamic behaviour indeed occurs. The importance of introducing fluorine atoms in these sugars mimics is also highlighted. Only the use of (19) F NMR spectroscopic experiments has permitted the unveiling of key features of the conformational equilibrium that would have otherwise remained unobserved.


Assuntos
Fatores Biológicos/química , Flúor/química , Hexoses/química , Hexoses/metabolismo , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Ressonância Magnética Nuclear Biomolecular , Termodinâmica
18.
Angew Chem Int Ed Engl ; 53(36): 9597-602, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-25044775

RESUMO

Molecular mimicry is an essential part of the development of drugs and molecular probes. In the chemical glycobiology field, although many glycomimetics have been developed in the past years, it has been considered that many failures in their use are related to the lack of the anomeric effects in these analogues. Additionally, the origin of the anomeric effects is still the subject of virulent scientific debates. Herein, by combining chemical synthesis, NMR methods, and theoretical calculations, we show that it is possible to restore the anomeric effect for an acetal when replacing one of the oxygen atoms by a CF2 group. This result provides key findings in chemical sciences. On the one hand, it strongly suggests the key relevance of the stereoelectronic component of the anomeric effect. On the other hand, the CF2 analogue adopts the natural glycoside conformation, which might provide new avenues for sugar-based drug design.


Assuntos
Dissacarídeos/síntese química , Acetais/química , Configuração de Carboidratos , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Mimetismo Molecular , Oxigênio/química , Estereoisomerismo
19.
Elife ; 132024 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-39302337

RESUMO

Glycans play an important role in modulating the interactions between natural killer cells and antibodies to fight pathogens and harmful cells.


Assuntos
Células Matadoras Naturais , Polissacarídeos , Polissacarídeos/metabolismo , Polissacarídeos/imunologia , Humanos , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Animais , Anticorpos/imunologia , Anticorpos/metabolismo
20.
ACS Cent Sci ; 10(5): 978-987, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38799664

RESUMO

Glycoconjugate vaccines so far licensed are generally composed of a native or size-reduced capsular polysaccharide conjugated to carrier proteins. Detailed information on the structural requirements necessary for CPS recognition is becoming the key to accelerating the development of next-generation improved glycoconjugate vaccines. Structural glycobiology studies using oligosaccharides (OS) complexed with functional monoclonal antibodies represent a powerful tool for gaining information on CPS immunological determinants at the atomic level. Herein, the minimal structural epitope of Haemophilus influenzae type b (Hib) CPS recognized by a functional human monoclonal antibody (hmAb) is reported. Short and well-defined Hib oligosaccharides originating from the depolymerization of the native CPS have been used to elucidate saccharide-mAb interactions by using a multidisciplinary approach combining surface plasmon resonance (SPR), saturation transfer difference-nanomagnetic resonance (STD-NMR), and X-ray crystallography. Our study demonstrates that the minimal structural epitope of Hib is comprised within two repeating units (RUs) where ribose and ribitol are directly engaged in the hmAb interaction, and the binding pocket fully accommodates two RUs without any additional involvement of a third one. Understanding saccharide antigen structural characteristics can provide the basis for the design of innovative glycoconjugate vaccines based on alternative technologies, such as synthetic or enzymatic approaches.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA