Lectin-carbohydrate Interaction Research Articles

Synthesis of a library of 2-fluoro-2-deoxy-derivatives of the trimannoside methyl α-D-Man-(1 → 3)-[α-D-Man-(1 → 6)]-α-D-Man and the dimannosides methyl α-D-Man-(1 → 3)-α-D-Man and methyl α-D-Man-(1 → 6)-α-D-Man

A library of sixteen compounds, 1–16, comprising all (mono-, di-, and tri-) 2-fluoro-2-deoxy-derivatives of the N-glycan core trimannoside α-D-Man-(1 → 3)-[α-D-Man-(1 → 6)]-D-Man, including the corresponding 2-fluoro-2-deoxy disaccharide part structures and the non-fluorinated parent compounds, have been synthesized as their α-methyl glycosides for use as tools in 19F NMR-based lectin-carbohydrate interaction studies. Two methyl 2-fluoro-2-deoxy-mannoside acceptors, 21 (3-OH) and 22 (6-OH), were constructed and used in combination with the corresponding non-fluorinated mannose acceptors, 24 (6-OH) and 25 (3-OH), the 2-fluoro-2-deoxy mannosyl bromide donor 18 and the non-fluorinated bromide donor 23 to efficiently afford the target di-and trisaccharides (disaccharides, 2–3 steps, 47–66% overall yield; trisaccharides, 4 steps, 25–40% overall yield).

SARS-CoV-2 Evolutionary Adaptation toward Host Entry and Recognition of Receptor O-Acetyl Sialylation in Virus-Host Interaction.

The recently emerged SARS-CoV-2 is the cause of the global health crisis of the coronavirus disease 2019 (COVID-19) pandemic. No evidence is yet available for CoV infection into hosts upon zoonotic disease outbreak, although the CoV epidemy resembles influenza viruses, which use sialic acid (SA). Currently, information on SARS-CoV-2 and its receptors is limited. O-acetylated SAs interact with the lectin-like spike glycoprotein of SARS CoV-2 for the initial attachment of viruses to enter into the host cells. SARS-CoV-2 hemagglutinin-esterase (HE) acts as the classical glycan-binding lectin and receptor-degrading enzyme. Most β-CoVs recognize 9-O-acetyl-SAs but switched to recognizing the 4-O-acetyl-SA form during evolution of CoVs. Type I HE is specific for the 9-O-Ac-SAs and type II HE is specific for 4-O-Ac-SAs. The SA-binding shift proceeds through quasi-synchronous adaptations of the SA-recognition sites of the lectin and esterase domains. The molecular switching of HE acquisition of 4-O-acetyl binding from 9-O-acetyl SA binding is caused by protein–carbohydrate interaction (PCI) or lectin–carbohydrate interaction (LCI). The HE gene was transmitted to a β-CoV lineage A progenitor by horizontal gene transfer from a 9-O-Ac-SA–specific HEF, as in influenza virus C/D. HE acquisition, and expansion takes place by cross-species transmission over HE evolution. This reflects viral evolutionary adaptation to host SA-containing glycans. Therefore, CoV HE receptor switching precedes virus evolution driven by the SA-glycan diversity of the hosts. The PCI or LCI stereochemistry potentiates the SA–ligand switch by a simple conformational shift of the lectin and esterase domains. Therefore, examination of new emerging viruses can lead to better understanding of virus evolution toward transitional host tropism. A clear example of HE gene transfer is found in the BCoV HE, which prefers 7,9-di-O-Ac-SAs, which is also known to be a target of the bovine torovirus HE. A more exciting case of such a switching event occurs in the murine CoVs, with the example of the β-CoV lineage A type binding with two different subtypes of the typical 9-O-Ac-SA (type I) and the exclusive 4-O-Ac-SA (type II) attachment factors. The protein structure data for type II HE also imply the virus switching to binding 4-O acetyl SA from 9-O acetyl SA. Principles of the protein–glycan interaction and PCI stereochemistry potentiate the SA–ligand switch via simple conformational shifts of the lectin and esterase domains. Thus, our understanding of natural adaptation can be specified to how carbohydrate/glycan-recognizing proteins/molecules contribute to virus evolution toward host tropism. Under the current circumstances where reliable antiviral therapeutics or vaccination tools are lacking, several trials are underway to examine viral agents. As expected, structural and non-structural proteins of SARS-CoV-2 are currently being targeted for viral therapeutic designation and development. However, the modern global society needs SARS-CoV-2 preventive and therapeutic drugs for infected patients. In this review, the structure and sialobiology of SARS-CoV-2 are discussed in order to encourage and activate public research on glycan-specific interaction-based drug creation in the near future.

Functional characterization of chitin-binding lectin from Solanum integrifolium containing anti-fungal and insecticidal activities

BackgroundAlong with the rapid development of glycomic tools, the study of lectin–carbohydrate interactions has expanded, opening the way for applications in the fields of analytic, diagnostic, and drug delivery. Chitin-binding lectins (CBLs) play roles in immune defense against chitin-containing pathogens. CBLs from species of the Solanaceae family, such as tomato, potato and jimsonweed, display different binding specificities to sugar chains containing poly-N-acetyllactosamine.ResultsIn this report, CBLs from Solanum integrifolium were isolated by ion exchange chromatography. The fractions showed hemagglutination activity (HA). The recombinant CBL in the 293F cell culture supernatant was able to inhibit the growth of Rhizoctonia solani and Colletotrichum gloeosporioide. Furthermore, the carbohydrate-binding property of CBLs was confirmed with the inhibition of HA. Binding of CBL to Spodoptera frugiperda (sf21) insect cells can partly be inhibited by N-Acetylglucosamine (GlcNAc), which is related to decrease mitochondrial membrane potential of sf21 cells.ConclusionsThe results showed that CBL exhibited antifungal properties and inhibited insect cell growth, which is directly correlated to the lectin-carbohydrate interaction. Further identification and characterization of CBLs will help to broaden their scope of application in plant defense and in biomedical applications.

Sauromatum guttatum lectin: Spectral studies, lectin-carbohydrate interaction, molecular cloning and in silico analysis

Non-immune carbohydrate binding proteins are broadly defined as lectins. Having been reported from all kingdoms of life, phytolectins are the most widely studied group of lectins. Sauromatum guttatum agglutinin (SGA) was isolated from the plant tubers and characterized for structural variations due to solvent perturbation using polarimetry, fluorescence and light scattering. For the β-sheet rich SGA, a pH and temperature induced molten globule like intermediate was identified. In isothermal titration microcalorimetry, SGA demonstrated cooperative binding to a complex glycoprotein in enthalpically driven mechanism. Fine sugar specificity exploration identified core pentasaccharide as the most common and highest binding motif with complex N-glycans and fucosylated core N-glycans as additional motifs. Molecular cloning of SGA which has previously been demonstrated to have anti-cancer and anti-insect activities is being reported for the first time. Full length cDNA sequence was obtained with RACE-PCR based upon the conserved carbohydrate recognition site [QXDXNXVXY] present in all GNA-related lectins. Quaternary structure was proposed by homology modeling and an attempt was made to explain the structure-function relationship by in silico analysis.

LBOS 02-03 THE INFILTRATING MACROPHAGE-SECRETED GALECTIN-3 PLAYS AN ESSENTIAL ROLE IN CARDIAC FIBROSIS AND DIASTOLIC FUNCTION IN MURINE PRESSURE-OVERLOAD MODEL

Objective: Cardiac fibrosis is the major pathophysiological process, contributing to the development of diastolic heart failure. We examine the role of macrophage-derived galectin-3 (gal-3) in cardiac fibrosis and diastolic function in response to transverse aortic constriction (TAC). Design and method: wild-type (WT) and gal-3 knock-out (KO) mice subjected to TAC; immunohistochemistry for myocardial macrophage infiltration,gal-3,and CTGF (connective tissue growth factor) expression; picrosirius red stain for myocardial fibrosis; FACS flow- cytometry for defining the origin of myocardial macrophages. MTT and Brdu incorporation for cell proliferation; flow-cytometry for cell differentiation; co-immunoprecipitation and confocal microscopy for lectin-carbohydrate interaction and co-localization respectively; echocardiography for left ventricular function. Results: WT mice after TAC showed significant increase of myocardial macrophage infiltration, gal-3 and CTGF expression, fibroblast proliferation/differentiation, and interstitial fibrosis leading to diastolic dysfunction, compared with controls (n = 10, p < 0.01). FACS flow-cytometry further identified that the increased myocardial macrophage population contains predominantly MHC-IIlow CCR2+ monocytes and MHC-IIhigh CCR2+ monocyte-derived macrophages. Macrophage depletion or gal-3 Knock-out mice markedly suppressed myocardial fibrosis. Re-administration of macrophages restored the fibrosis. In in-vitro, confocal microscopy and co-immunoprecipitation confirmed co-localization and gal-3-EGFR interaction on cell membrane. Treatment with recombinant gal-3 increased EGFR and downstream ERK phosphorylation, and CTGF expression in wild-type or gal-3 knock-down fibroblasts. Moreover, using MTT and Brdu incorporation assays, addition of gal-3, or macrophage-derived supernatant, or co-culture with macrophages significantly promoted fibroblast proliferation via CTGF expression. Finally, administration of gal-3 neutralizing monoclonal antibody remarkably reversed the myocardial fibrosis and improved diastolic function. Conclusions: Pressure-overload promotes myocardial macrophage infiltration and the macrophage -secreted gal-3 cross-links with its glycoconjugate, EGFR, resulting in its autophosphorylation, activation of subsequent mitogenic ERK signaling, myocardial CTGF expression, fibroblast proliferation/differentiation, resulting in myocardial fibrosis and diastolic dysfunction. Our findings provide molecular basis for gal-3 as a promising therapeutic target in heart failure.

Gal/GalNAc specific multiple lectins in marine bivalve Anadara granosa.

Complete lectin mapping of molluscs with their diversified recognition pattern and possible role in lectin-carbohydrate interaction based immune response triggering need much attention. In this communication, Gal/GalNAc specific three lectins AGL-IA (Anadara granosa lectin-IA), AGL-IB (A. granosa lectin-IB) and AGL-IV (A. granosa lectin-IV) and a lectin having hemolytic activity AGL-III (A. granosa lectin-III) were purified from the plasma of A. granosa bivalve by a combination of gel filtration and affinity chromatography. AGL-IA and IB were oligomeric lectins whereas, AGL-III and IV were monomeric. The molecular weight of AGL-IA, IB, III and IV were 375, 260, 45 and 33 kDa respectively. AGL-IA and IV agglutinated both rabbit and pronase treated human erythrocytes, whereas AGL-IB agglutinated only rabbit erythrocytes. AGL-III was found to agglutinate rabbit erythrocytes, however, it caused hemolysis of pronase treated human erythrocytes. The activity of all four lectins was calcium dependent and maximum at a pH range 7-8. Apart from Gal/GalNAc specific, the four lectins showed substantial differences in their carbohydrate recognition pattern. Moreover, there was a difference in the carbohydrate specificity between AGL-III and other three lectins (AGL-IA, AGL-IB and AGL-IV) towards polyvalent glycotope. On the one hand, 'cluster glycoside effect' i.e., an enhancement of the activity of a multivalent ligand, was observed for carbohydrate specificities of AGL-IA, AGL-IB, AGL-IV. On the other hand, the effect of multivalent ligands on the carbohydrate specificity of AGL-III was opposite of cluster glycoside effect. The affinity of AGL-IA, AGL-IB and AGL-IV for ligands can be ranked as follows: glycoproteins >> polysaccharide > oligosaccharides and monosaccharides. However, Gal related monosaccharides were the best inhibitors of AGL-III and the inhibitory activity decreased gradually in the following order: monosaccharide > disaccharide > polysaccharide. Thus, the diverse specificity of multiple lectins in A. granosa plasma possibly enables to recognize a wide range of microorganisms.

Study of Bacterial Adhesion on Biomimetic Temperature Responsive Glycopolymer Surfaces

Pseudomonas aeruginosa is an opportunistic pathogen responsible for diseases such as bacteremia, chronic lung infection, and acute ulcerative keratitis. P. aeruginosa induced diseases can be fatal as the exotoxins and endotoxins released by the bacterium continue to damage host tissues even after the administration of antibiotics. As bacterial adhesion on cell surfaces is the first step in bacterial based pathogen infections, the control of bacteria-cell interactions is a worthwhile research target. In this work, thermally responsive poly(N-isopropylacrylamide) [P(NIPAAm)] based biomimetic surfaces were developed to study the two major bacterial infection mechanisms, which is believed to be mediated by hydrophobic or lectin-carbohydrate interactions, using quartz crystal microbalance with dissipation. Although, a greater number of P. aeruginosa adhered to the NIPAAm homopolymer modified surfaces at temperatures higher than the lower critical solution temperature (LCST), the bacterium-substratum bond stiffness was stronger between P. aeruginosa and a galactose based P(NIPAAm) surface. The high bacterial adhesion bond stiffness observed on the galactose based thermally responsive surface at 37 °C might suggest that both hydrophobic and lectin-carbohydrate interactions contribute to bacterial adhesion on cell surfaces. Our investigation also suggests that the lectin-carbohydrate interaction play a significant role in bacterial infections.

Human Trefoil Factor 2 Is a Lectin That Binds α-GlcNAc-capped Mucin Glycans with Antibiotic Activity against Helicobacter pylori

Helicobacter pylori infection is the major cause of gastric cancer and remains an important health care challenge. The trefoil factor peptides are a family of small highly conserved proteins that are claimed to play essential roles in cytoprotection and epithelial repair within the gastrointestinal tract. H. pylori colocalizes with MUC5AC at the gastric surface epithelium, but not with MUC6 secreted in concert with TFF2 by deep gastric glands. Both components of the gastric gland secretome associate non-covalently and show increased expression upon H. pylori infection. Although blood group active O-glycans of the Lewis-type form the basis of H. pylori adhesion to the surface mucin layer and to epithelial cells, α1,4-GlcNAc-capped O-glycans on gastric mucins were proposed to inhibit H. pylori growth as a natural antibiotic. We show here that the gastric glycoform of TFF2 is a calcium-independent lectin, which binds with high specificity to O-linked α1,4-GlcNAc-capped hexasaccharides on human and porcine stomach mucin. The structural assignments of two hexasaccharide isomers and the binding active glycotope were based on mass spectrometry, linkage analysis, (1)H nuclear magnetic resonance spectroscopy, glycan inhibition, and lectin competition of TFF2-mucin binding. Neoglycolipids derived from the C3/C6-linked branches of the two isomers revealed highly specific TFF2 binding to the 6-linked trisaccharide in GlcNAcα1-4Galβ1-4GlcNAcβ1-6(Fucα1-2Galβ1-3)GalNAc-ol(Structure 1). Supposedly, lectin TFF2 is involved in protection of gastric epithelia via a functional relationship to defense against H. pylori launched by antibiotic α1,4-GlcNAc-capped mucin glycans. Lectin-carbohydrate interaction may have also an impact on more general functional aspects of TFF members by mediating their binding to cell signaling receptors.

Sweet taste of cell death: role of carbohydrate recognition systems

T he number of cellular and molecular markers of apoptosis described in cytoplasm, nucleus and mitochondria, is increasing yearly. Howe ver, up to recent time, plasma membrane (PM) markers stayed to be less studied [1], and only phosphatidylserine (PS) externalization has been well characterized in that compartment, and already proposed for application in biolo gy studies and medical diagnostics [2]. It should be stressed that PM markers of apoptosis possess some important advantages compared to all other markers of this phenomenon, since they are better accessible to extra-cellular interactions without disturbing cell integrity. Since PM markers of apoptotic cells can be recognized by the phagocytic and neighboring epithelial cells, they are very important for efficient elimination of apoptotic cells from tissues and organs. Cell death was shown to be accompanied by time-dependent sequence of intracellular events, starting with a trigger signal and ending with a complete removal of dying cells by their neighbors and macrophages. It is discussed since when one can consider the cell “dead” or “apoptotic”. The organism senses the dying cells by a change of their surface markers and by a release of particular intercellular molecules [3] also related to changes in plasma membrane. Thus, the PM-derived apoptosis markers seem to be the most “physiological” measure of whether the cell is alive, dying, or already dead (necrotic). Recently, glycoproteins (GPs) integrated in the PM of apoptotic cells, were addressed by the investigators searching for novel cell surface markers of apoptosis. The carbohydrate moiety of plasma membrane GPs, unlike the DNA or proteins, does not need a specific matrix for its synthesis. Besides, unlike 3′→5′ phospodiester bonds in DNA, or peptide bonds in proteins, two carbohydrate molecules can be joined together by eleven different bond combinations providing a huge number of possible oligosaccharides and much higher information potential that is perfectly described by H.-J. Gabius [4]. Carbohydrate binding proteins, the lectins, have demonstrated to be a powerful tool for recognizing different carbohydrate moieties. They were discovered over 100 years ago, and hundreds of lectins with various carbohydrate specificity and different functions were described in plants and animals [5, 6]. A principal function of lectin-carbohydrate interaction is well expressed at the immune response [7, 8], including autoimmunity [9], and cell elimination from the organism [10]. It was hypothesized [11], that such interaction could be an evolutionary ancestor of the antibody-antigen interaction.

N-Acetylglucosamine biofunctionalized CdSeTe quantum dots as fluorescence probe for specific protein recognition

Hsp70 proteins are implicated in resistance to chemotherapy in cancers, the detection of which is important for cancer treatment and prognosis. In this work, we report the study on the detection of specific intracellular target protein in fixed cells using GlcNAc-conjugated CdSeTe QDs. The QDs were coupled with ConA via a carbodiimide reaction and then were further assembled with GlcNAc by lectin-carbohydrate interaction between ConA and GlcNAc. The obtained QDs-ConA-GlcNAc conjugates have an emission wavelength at 650 nm that is close to the near-infrared (NIR) regions and a specific recognition for Hsp70. These results show that the QDs-ConA-GlcNAc probe can be a promising tool for direct localization of the Hsp70 protein.

Controlling morphology of peptide‐based soft structures by covalent modifications

Control of gross morphology of soft matter remains an area of continued interest. Towards this goal, this paper describes conjugation of mannose residues and introduction of thiol functionalities to diphenylalanine (FF) dipeptide, a fibrillating motif from amyloid-β peptide, as covalent modifiers of its solution-phase self-assembly process. It was found that covalent attachment of a single mannose residue to FF leads to the retention of tubular structures, whereas the conjugation of two mannose units, linked through a Lys residue, resulted in a dramatic change from tubular morphology to spherical structures. However, a similar switch to spherical objects could be achieved by introducing a thiol residue in the mono-mannosylated FF dipeptide. Interestingly, these glycopeptides also exhibited interaction with concanavalin A, thereby providing an indirect evidence for the availability of mannose units for the process of lectin-carbohydrate interaction in the self-organized state.

Molecular recognition force spectroscopy of a specific lectin–carbohydrate interaction at single-molecule level

Carbohydrates are involved in many essential biological recognition processes in physiological and pathological states. Thus, it is important to understand the mechanism of protein-carbohydrate interactions at molecular level. In the present study, molecular recognition force spectroscopy was applied to investigate the interactions between RCA₁₂₀, a lectin from Ricinus communis, and galactose (Gal) and asialofetuin (ASF) at the single-molecule level. RCA₁₂₀ coupled to the AFM tip could specifically recognize Gal and ASF, respectively. The unbinding forces of RCA₁₂₀-Gal and RCA₁₂₀-ASF increase linearly with the logarithm of loading rate. The results reveal that the binding capability of RCA₁₂₀ toward Gal is weaker than that of ASF, implicating a multivalent effect in the RCA₁₂₀-ASF interaction.

Host–parasite interactions and host species susceptibility of the marine oomycete parasite, Olpidiopsis sp., from Korea that infects red algae

Porphyra farms in Korea occasionally suffer from Olpidiopsis infection. As Porphyra farming proceeds from October to March, this obligatory biotrophic parasite may need an alternative host to survive during other months of the year. To find a possible alternative summer host, we collected algae from Wando, Korea, where extensive Porphyra plantations are located, and discovered an oomycete assignable to the genus Olpidiopsis from Heterosiphonia pulchra. Host susceptibility tests showed that this oomycete could also infect Heterosiphonia japonica, Dasya sp., Dasysiphonia chejuensis, and also blades of Porphyra tenera. The minimum incubation time for this Olpidiopsis sp. to infect its hosts was approximately 4 h. Zoosporangia matured in 2 days and biflagellate zoospores were released. Free zoospores remained infective in seawater for up to 7 days. The infection of Olpidiopsis sp. to H. japonica was cell-type specific and extended rhizoid-like apical cells of determinate branches were preferentially infected. FITC-conjugated lectin staining showed specific binding of concanavalin A (ConA) to extended rhizoid-like apical cells. Attachment of Olpidiopsis sp. zoospores to the host cells was inhibited by α-mannosidase. Monosaccharide inhibition experiments showed that d(+)-mannose, complementary to the lectin ConA, could also block the infection, suggesting a lectin–carbohydrate interaction during host–parasite recognition.

Molecular-engineered polymeric microcapsules assembled from Concanavalin A and glycogen with specific responses to carbohydrates

Hollow polymeric microcapsules with specific responses to mannose, fructose, glucose and its corresponding polysaccharide, dextran, at the physiological pH range were fabricated from Concanavalin A, a plant lectin, and glycogen, a polysaccharide, based on the lectin–carbohydrate interaction in a layer-by-layer fashion. The growth pattern of the multilayer film was largely influenced by the environmental pH condition. Hollow capsules with variable size and wall thickness were obtained by assembly on CaCO3 microparticles and subsequent template removal. The as-prepared capsules remained stable in the pH range 6–9 for 1 h and could survive 3 M urea treatment for at least 1 h. They could specifically respond to or even be destroyed by mannose, fructose, glucose and dextran (Mw 20 kDa and 40 kDa) at the physiological pH condition, but not by other types of carbohydrates such as lactose and galactose. The responses were dependent on both the molecular weight and the concentration of the carbohydrates regardless of the environmental pH condition (pH 6–9). Finally, the capsules were employed as delivery vehicles for poly(styrene-b-acrylic acid) (PS-b-PAA) micelles, which could be partly released under the triggering of glucose or dextran (Mw 20 kDa). With the combination of good stability and specific responsiveness to various carbohydrates, as well as the possibility of loading and releasing functional nano-objects, these microcapsules could be promising candidates as advanced drug delivery carriers and micro-reactors.

Flocculation protein structure and cell–cell adhesion mechanism in Saccharomyces cerevisiae

Cell-cell adhesion occurs in a broad spectrum of biological processes, of which yeast flocculation is an area of interest for evolutionary scientists to brewers and winemakers. The flocculation mechanism is based on a lectin-carbohydrate interaction but is not yet fully understood, although the first model dates back to the 1950s. This review will update the current understanding of the complex mechanism behind yeast flocculation. Moreover, modern technologies to measure the forces involved in single carbohydrate-lectin interactions, are discussed. The Flo1 protein has been extensively described as the protein responsible for strong flocculation. Recently, more research has been directed to the detailed analysis of this flocculin. Due to the advances in the field of bioinformatics, more information about Flo1p could be obtained via structurally or functionally related proteins. Here, we review the current knowledge of the Flo1 protein, with a strong emphasis towards its structure.

Multivalent Biomimetic Glyconanoparticle Platforms as QCM Amplifiers for Lectin-carbohydrate Interactions

AbstractThe Lectin-Carbohydrate interaction was investigated by combining the Quartz Crystal Microbalance-QCM technique with signal amplifying biomimetic nanoparticle-NP platforms. A library of glyconanoparticles was prepared and the avidity of these NPs for immobilised lectin layers was then evaluated by a QCM setup. Large responses were observed as a result of surface recognition by nanoparticles displaying the appropriate molecular functionality. Large affinity enhancements were also in evidence due to the biomimetic nature of the glyconanoparticle assemblies' carbohydrate presentation demonstrating evidence of the cluster glycoside effect.

Inhibition of adherence of corynebacterium diphtheriae to human buccal epitelium by glycoside hydrolases of marine hydrobiontes

A possibility of adhesion inhibition of Corynebacterium diphtheriae to human buccal epithelium by glycoside hydrolases of marine hydrobiontes was investigated using alpha-galactosidase from marine bacterium Pseudoalteromonas sp. KMM 701, total enzyme preparation and beta-1,3-glucanase from marine fungi Chaetomium, total enzyme preparation and beta-1,3-glucanase from marine mollusk Littorina kurila, and total enzyme preparation from crystalline style of marine mollusk Spisula sachalinensis were used. The enzymes were added to test-tubes containing buccal epithelial cells and/or the toxigenic bacterial strain C. diphtheriae No 1129, v. gravis. All the investigated enzymes were able to abort C. diphtheriae adherence, to human buccal epithelocytes. Inhibition of adhesion was more pronounced in the case of treatment of epithelocytes with highly purified enzymes of marine hydrobiontes in comparison with total enzyme preparations. The significant inhibition of C. diphtheriae adhesion was observed when the enzymes were added to the epithelocytes with the attached microorganisms. The results obtained show that glycoside hydrolases of marine hydrobiontes degrade any carbohydrates expressed on cell surface of bacterium or human buccal epithelocytes, impair unique lectin-carbohydrate interaction and prevent the adhesion.

Ru(II) Glycodendrimers as Probes to Study Lectin−Carbohydrate Interactions and Electrochemically Measure Monosaccharide and Oligosaccharide Concentrations

We describe a novel platform on which to study carbohydrate-protein interactions based on ruthenium(II) glycodendrimers as optical and electrochemical probes. Using the prototypical concanavalin A (ConA)-mannose lectin-carbohydrate interaction as an example, oligosaccharide concentrations were electrochemically monitored. The displacement of the Ru(II) complex from lectin-functionalized gold surfaces was repeatedly regenerated. This new platform presents a method to monitor many different complex sugars in parallel.

Síntese de β-D-galactopiranosídeos de arila diméricos para avaliação de sua interação com a lectina de Erythrina cristagalli

WITH THE Erythrina cristagalli LECTIN. The synthesis of two new D-galactose-based dimers having a 1,4-butanediamine spacer is reported aiming at the evaluation of their interaction with the Erythrina cristagalli lectin. The title compounds were prepared in four and five steps from 2,3,4,6-tetra- O-acetyl-b-D-galactopyranoside bromide, in 20 % and 15 % overall yield, respectively, using the Doebner modification of the Koenavenagel reaction as the key sep. The lectin-carbohydrate interaction could be evaluated for only one dimer, due to solubility problems. A twofold enhancement of affinity was observed, compared to the corresponding monovalent ligand.

Galectin‐3 Stimulates Preadipocyte Proliferation and Is Up‐regulated in Growing Adipose Tissue

Some cytokines and mediators of inflammation can alter adiposity through their effects on adipocyte number. To probe the molecular basis of obesity, this study determined whether galectin-3 was present in adipose tissue and investigated its effects on fat cell number. In the first study, obesity-prone C57BL/6J mice were fed with high-fat (58%) diet. Epididymal fat pads were collected at Day 0, Day 60, and Day 120 after the start of high-fat feeding. Levels of adipocyte galectin-3 protein, determined using Western blot analysis, increased as the mice became obese. Galectin-3 mRNA and protein were then detected in human adipose tissue, primarily in the preadipocyte fraction. It was found that recombinant human galectin-3 stimulated proliferation of primary cultured preadipocytes as well as DNA synthesis through lectin-carbohydrate interaction. Galectin-3, which has been known to play a versatile role especially in immune cells, might play a role also in adipose tissue and be associated with the pathophysiology of obesity.