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Biomacromolecules Jun 2012We present for the first time the synthesis of sequence-defined monodisperse glycopolymer segments via solid-phase polymer synthesis. Functional building blocks...
We present for the first time the synthesis of sequence-defined monodisperse glycopolymer segments via solid-phase polymer synthesis. Functional building blocks displaying alkyne moieties and hydrophilic ethylenedioxy units were assembled stepwise on solid phase. The resulting polymer segments were conjugated with mannose sugars via 1,3-dipolar cycloaddition. The obtained mono-, di-, and trivalent mannose structures were then subject to Con A lectin binding. Surface plasmon resonance studies showed a nonlinear increase in binding regarding the number and spacing of sugar ligands. The results of Con A lectin binding assays indicate that the chemical composition of the polymeric scaffold strongly contributes to the binding activities as well as the spacing between the ligands and the number of presented mannose units. Our approach now allows for the synthesis of highly defined glycooligomers and glycopolymers with a diversity of properties to investigate systematically multivalent effects of polymeric ligands.
Topics: Binding Sites; Concanavalin A; Mannose; Polysaccharides
PubMed: 22483345
DOI: 10.1021/bm300331z -
Current Opinion in Structural Biology Jun 2020Mannosidases are a diverse group of enzymes that are important in the biological processing of mannose-containing polysaccharides and complex glycoconjugates. They are... (Review)
Review
Mannosidases are a diverse group of enzymes that are important in the biological processing of mannose-containing polysaccharides and complex glycoconjugates. They are found in 12 of the >160 sequence-based glycosidase families. We discuss evidence that nature has evolved a small set of common mechanisms that unite almost all of these mannosidase families. Broadly, mannosidases (and the closely related rhamnosidases) perform catalysis through just two conformations of the oxocarbenium ion-like transition state: a B (or enantiomeric B) boat and a H half-chair. This extends to a new family (GT108) of GDPMan-dependent β-1,2-mannosyltransferases/phosphorylases that perform mannosyl transfer through a boat conformation as well as some mannosidases that are metalloenzymes and require divalent cations for catalysis. Yet, among this commonality lies diversity. New evidence shows that one unique family (GH99) of mannosidases use an unusual mechanism involving anchimeric assistance via a 1,2-anhydro sugar (epoxide) intermediate.
Topics: Biocatalysis; Mannose; Mannosidases; Molecular Conformation
PubMed: 31891872
DOI: 10.1016/j.sbi.2019.11.008 -
Biochimica Et Biophysica Acta Mar 1999The aim of the present study was to explore how mannose enters fibroblasts derived from a panel of children suffering from different subtypes of type I carbohydrate...
The aim of the present study was to explore how mannose enters fibroblasts derived from a panel of children suffering from different subtypes of type I carbohydrate deficient glycoprotein syndrome: seven carbohydrate deficient glycoprotein syndrome subtype Ia (phosphomannomutase deficiency), two carbohydrate deficient glycoprotein syndrome subtype Ib (phosphomannose isomerase deficiency) and two carbohydrate deficient glycoprotein syndrome subtype Ix (not identified deficiency). We showed that a specific mannose transport system exists in all the cells tested but has different characteristics with respect to carbohydrate deficient glycoprotein syndrome subtypes. Subtype Ia fibroblasts presented a mannose uptake equivalent or higher (maximum 1.6-fold) than control cells with a D-[2-3H]-mannose incorporation in nascent N-glycoproteins decreased up to 7-fold. Compared to control cells, the mannose uptake was greatly stimulated in subtype Ib (4.0-fold), due to lower Kuptake and higher Vmax values. Subtype Ib cells showed an increased incorporation of D-[2-3H]-mannose into nascent N-glycoproteins. Subtype Ix fibroblasts presented an intermediary status with mannose uptake equivalent to the control but with an increased incorporation of D-[2-3H]-mannose in nascent N-glycoproteins. All together, our results demonstrate quantitative and/or qualitative modifications in mannose transport of all carbohydrate deficient glycoprotein syndrome fibroblasts in comparison to control cells, with a relative homogeneity within a considered subtype of carbohydrate deficient glycoprotein syndrome. These results are consistent with the possible use of mannose as a therapeutic agent in carbohydrate deficient glycoprotein syndrome Ib and Ix.
Topics: Biological Transport; Cells, Cultured; Congenital Disorders of Glycosylation; Fibroblasts; Glycoproteins; Humans; Mannose; Skin
PubMed: 10101255
DOI: 10.1016/s0925-4439(99)00009-5 -
The Journal of Clinical Endocrinology... Jul 2012The aim of this study was to determine relative contributions of transplacental flux vs. fetal production for inositol and mannose in normal term pregnancies. (Clinical Trial)
Clinical Trial
OBJECTIVE
The aim of this study was to determine relative contributions of transplacental flux vs. fetal production for inositol and mannose in normal term pregnancies.
STUDY DESIGN
Seven term uncomplicated pregnancies undergoing cesarean section were infused with (13)C- and (2)H-labeled isotopes of glucose, inositol, and mannose until a steady state was achieved. Maternal and fetal concentrations of labeled and unlabeled glucose, mannose, and inositol were measured using gas chromatography/mass spectroscopy. The fetomaternal molar percentage excess ratio was calculated for each glucose, mannose, and inositol.
RESULTS
The fetomaternal molar percentage excess ratio of mannose in the fetal artery (F(artery)/M) was 0.99 [97.5% confidence interval (CI), 0.91-1.07] and in the fetal vein (F(vein)/M), 1.02 (97.5% CI, 0.95-1.10). Both were not significantly different from 1.0, consistent with transplacental supply. The fetomaternal ratios for glucose were similar to mannose (fetal artery, 0.95; 97.5% CI, 0.84-1.15; and fetal vein, 0.96; 97.5% CI, 0.85-1.07). The fetomaternal ratio for inositol was significantly less than 1.0 (fetal artery, 0.08; 97.5% CI, 0.05-0.12; fetal vein, 0.12; 97.5% CI, 0.06-0.18), indicating little transplacental flux and significant fetal production.
CONCLUSION
In normal term pregnancies, fetal mannose and glucose concentrations are dependent upon maternal transplacental supply. Fetal inositol is not dependent upon transplacental supply.
Topics: Adult; Carbon Isotopes; Cesarean Section; Female; Humans; Hydrogen; Infant, Newborn; Inositol; Isotope Labeling; Male; Mannose; Maternal-Fetal Exchange; Placenta; Placental Circulation; Pregnancy; Pregnancy Complications
PubMed: 22544916
DOI: 10.1210/jc.2011-1800 -
Organic & Biomolecular Chemistry Apr 2014The oligosaccharides Man4 and Man5, substructures of the high-mannose glycans of HIV glycoprotein gp120, were synthesized with a terminal 1-thiomannopyranose residue....
The oligosaccharides Man4 and Man5, substructures of the high-mannose glycans of HIV glycoprotein gp120, were synthesized with a terminal 1-thiomannopyranose residue. The anomeric thiol can be readily converted to an azidomethyl aglycone through reaction with dichloromethane and displacement with sodium azide. The resulting oligomannans were then conjugated to ubiquitin utilizing thiol alkylation or azide/alkyne reactive tethers of minimal length. By combining high efficiency conjugation reactions and a short tether, we sought to establish conjugation conditions that would permit high density clustering of oligomannans in conjugate vaccines that could produce antibodies able to bind gp120 and potentially neutralize virus. LC-UV-MS was used to separate, identify and quantify the ubiquitin glycoconjugates with differing degrees of oligomannan incorporation. Binding of the HIV protective monoclonal antibody 2G12 and concanavalin A to microtitre plates coated with glycoconjugates was measured by ELISA.
Topics: HIV Envelope Protein gp120; Mannose; Models, Molecular; Molecular Structure; Polysaccharides
PubMed: 24549150
DOI: 10.1039/c3ob42194e -
Journal of Mass Spectrometry : JMS Mar 2016The isomeric structure of high-mannose N-glycans can significantly impact biological recognition events. Here, the utility of travelling-wave ion mobility mass...
The isomeric structure of high-mannose N-glycans can significantly impact biological recognition events. Here, the utility of travelling-wave ion mobility mass spectrometry for isomer separation of high-mannose N-glycans is investigated. Negative ion fragmentation using collision-induced dissociation gave more informative spectra than positive ion spectra with mass-different fragment ions characterizing many of the isomers. Isomer separation by ion mobility in both ionization modes was generally limited, with the arrival time distributions (ATD) often showing little sign of isomers. However, isomers could be partially resolved by plotting extracted fragment ATDs of the diagnostic fragment ions from the negative ion spectra, and the fragmentation spectra of the isomers could be extracted by using ions from limited areas of the ATD peak. In some cases, asymmetric ATDs were observed, but no isomers could be detected by fragmentation. In these cases, it was assumed that conformers or anomers were being separated. Collision cross sections of the isomers in positive and negative fragmentation mode were estimated from travelling-wave ion mobility mass spectrometry data using dextran glycans as calibrant. More complete collision cross section data were achieved in negative ion mode by utilizing the diagnostic fragment ions. Examples of isomer separations are shown for N-glycans released from the well-characterized glycoproteins chicken ovalbumin, porcine thyroglobulin and gp120 from the human immunodeficiency virus. In addition to the cross-sectional data, details of the negative ion collision-induced dissociation spectra of all resolved isomers are discussed.
Topics: Animals; Carbohydrate Sequence; Chickens; Glycoproteins; Ions; Mannose; Mass Spectrometry; Polysaccharides; Swine
PubMed: 26956389
DOI: 10.1002/jms.3738 -
Bioconjugate Chemistry Jun 2018High-mannose-type N-glycans are an important component of neutralizing epitopes on HIV-1 envelope glycoprotein gp120. They also serve as signals for protein folding,...
High-mannose-type N-glycans are an important component of neutralizing epitopes on HIV-1 envelope glycoprotein gp120. They also serve as signals for protein folding, trafficking, and degradation in protein quality control. A number of lectins and antibodies recognize high-mannose-type N-glycans, and glycan array technology has provided an avenue to probe these oligomannose-specific proteins. We describe in this paper a top-down chemoenzymatic approach to synthesize a library of high-mannose N-glycans and related neoglycoproteins for glycan microarray analysis. The method involves the sequential enzymatic trimming of two readily available natural N-glycans, the ManGlcNAcAsn prepared from soybean flour and the sialoglycopeptide (SGP) isolated from chicken egg yolks, coupled with chromatographic separation to obtain a collection of a full range of natural high-mannose N-glycans. The Asn-linked N-glycans were conjugated to bovine serum albumin (BSA) to provide neoglycoproteins containing the oligomannose moieties. The glycoepitopes displayed were characterized using an array of glycan-binding proteins, including the broadly virus-neutralizing agents, glycan-specific antibody 2G12, Galanthus nivalis lectin (GNA), and Narcissus pseudonarcissus lectin (NPA).
Topics: Animals; Biocatalysis; Cattle; Chickens; Glycoproteins; Mannose; Polysaccharides; Serum Albumin, Bovine; Glycine max
PubMed: 29738673
DOI: 10.1021/acs.bioconjchem.8b00145 -
Faraday Discussions Oct 2019Porous glycopolymers, "glycomonoliths", were prepared by radical polymerization based on polymerization-induced phase separation with an acrylamide derivative of...
Porous glycopolymers, "glycomonoliths", were prepared by radical polymerization based on polymerization-induced phase separation with an acrylamide derivative of α-mannose, acrylamide and cross-linker in order to investigate protein adsorption and separation. The porous structure was induced by a porogenic alcohol. The pore diameter and surface area were controlled by the type of alcohol. The protein adsorption was measured in both batch and continuous flow systems. The glycomonoliths showed specific interaction with the sugar recognition protein of concanavalin A, and non-specific interaction to other proteins was negligible. The amount of protein adsorption to the materials was determined by the sugar density and the composition of the glycomonoliths. Fundamental knowledge regarding the glycomonoliths for protein separation was obtained.
Topics: Acrylamide; Adsorption; Concanavalin A; Glycoconjugates; Mannose; Membranes, Artificial; Phase Transition; Polymerization; Porosity
PubMed: 31313794
DOI: 10.1039/c9fd00018f -
Biochemical and Biophysical Research... Oct 1982
Topics: Animals; Glucose; In Vitro Techniques; Insulin; Insulin Secretion; Islets of Langerhans; Isomerism; Kinetics; Mannose; Rats; Structure-Activity Relationship
PubMed: 6758784
DOI: 10.1016/s0006-291x(82)80086-7 -
Glycoconjugate Journal Jul 2013High-mannose type N-linked glycan with 6 mannosyl residues, termed "M6Gn2", displayed clear binding to the same M6Gn2, conjugated with ceramide mimetic (cer-m) and...
High-mannose type N-linked glycan with 6 mannosyl residues, termed "M6Gn2", displayed clear binding to the same M6Gn2, conjugated with ceramide mimetic (cer-m) and incorporated in liposome, or coated on polystyrene plates. However, the conjugate of M6Gn2-cer-m did not interact with complex-type N-linked glycan with various structures having multiple GlcNAc termini, conjugated with cer-m. The following observations indicate that hamster embryonic fibroblast NIL-2 K cells display homotypic autoadhesion, mediated through the self-recognition capability of high-mannose type glycans expressed on these cells: (i) NIL-2 K cells display clear binding to lectins capable of binding to high-mannose type glycans (e.g., ConA), but not to other lectins capable of binding to other carbohydrates (e.g. GS-II). (ii) NIL-2 K cells adhere strongly to plates coated with M6Gn2-cer-m, but not to plates coated with complex-type N-linked glycans having multiple GlcNAc termini, conjugated with cer-m; (iii) degree of NIL-2 K cell adhesion to plates coated with M6Gn2-cer-m showed a clear dose-dependence on the amount of M6Gn2-cer-m; and (iv) the degree of NIL-2 K adhesion to plates coated with M6Gn2-cer-m was inhibited in a dose-dependent manner by α1,4-L-mannonolactone, the specific inhibitor in high-mannose type glycans addition. These data indicate that adhesion of NIL-2 K is mediated by self-aggregation of high mannose type glycan. Further studies are to be addressed on auto-adhesion of other types of cells based on self interaction of high mannose type glycans.
Topics: Animals; Cell Adhesion; Cell Line; Ceramides; Cricetinae; Dose-Response Relationship, Drug; Embryo, Mammalian; Fibroblasts; Glycoconjugates; Lactones; Mannose; Mice; Molecular Mimicry; Polysaccharides
PubMed: 23007868
DOI: 10.1007/s10719-012-9449-3