The Experts below are selected from a list of 1239 Experts worldwide ranked by ideXlab platform
Werner Reutter - One of the best experts on this subject based on the ideXlab platform.
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metabolic glycoengineering with n acyl side chain modified Mannosamines
Angewandte Chemie, 2016Co-Authors: Paul R Wratil, Rudiger Horstkorte, Werner ReutterAbstract:In metabolic glycoengineering (MGE), cells or animals are treated with unnatural derivatives of monosaccharides. After entering the cytosol, these sugar analogues are metabolized and subsequently expressed on newly synthesized glycoconjugates. The feasibility of MGE was first discovered for sialylated glycans, by using N-acyl-modified Mannosamines as precursor molecules for unnatural sialic acids. Prerequisite is the promiscuity of the enzymes of the Roseman–Warren biosynthetic pathway. These enzymes were shown to tolerate specific modifications of the N-acyl side chain of Mannosamine analogues, for example, elongation by one or more methylene groups (aliphatic modifications) or by insertion of reactive groups (bioorthogonal modifications). Unnatural sialic acids are incorporated into glycoconjugates of cells and organs. MGE has intriguing biological consequences for treated cells (aliphatic MGE) and offers the opportunity to visualize the topography and dynamics of sialylated glycans in vitro, ex vivo, and in vivo (bioorthogonal MGE).
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biochemical engineering of the n acyl side chain of sialic acid biological implications
Glycobiology, 2001Co-Authors: Oliver T Keppler, Michael Pawlita, Rudiger Horstkorte, Carolin Schmidt, Werner ReutterAbstract:: N-Acetylneuraminic acid is the most prominent sialic acid in eukaryotes. The structural diversity of sialic acid is exploited by viruses, bacteria, and toxins and by the sialoglycoproteins and sialoglycolipids involved in cell-cell recognition in their highly specific recognition and binding to cellular receptors. The physiological precursor of all sialic acids is N-acetyl D-Mannosamine (ManNAc). By recent findings it could be shown that synthetic N-acyl-modified D-Mannosamines can be taken up by cells and efficiently metabolized to the respective N-acyl-modified neuraminic acids in vitro and in vivo. Successfully employed D-Mannosamines with modified N-acyl side chains include N-propanoyl- (ManNProp), N-butanoyl- (ManNBut)-, N-pentanoyl- (ManNPent), N-hexanoyl- (ManNHex), N-crotonoyl- (ManNCrot), N-levulinoyl- (ManNLev), N-glycolyl- (ManNGc), and N-azidoacetyl D-Mannosamine (ManNAc-azido). All of these compounds are metabolized by the promiscuous sialic acid biosynthetic pathway and are incorporated into cell surface sialoglycoconjugates replacing in a cell type-specific manner 10-85% of normal sialic acids. Application of these compounds to different biological systems has revealed important and unexpected functions of the N-acyl side chain of sialic acids, including its crucial role for the interaction of different viruses with their sialylated host cell receptors. Also, treatment with ManNProp, which contains only one additional methylene group compared to the physiological precursor ManNAc, induced proliferation of astrocytes, microglia, and peripheral T-lymphocytes. Unique, chemically reactive ketone and azido groups can be introduced biosynthetically into cell surface sialoglycans using N-acyl-modified sialic acid precursors, a process offering a variety of applications including the generation of artificial cellular receptors for viral gene delivery. This group of novel sialic acid precursors enabled studies on sialic acid modifications on the surface of living cells and has improved our understanding of carbohydrate receptors in their native environment. The biochemical engineering of the side chain of sialic acid offers new tools to study its biological relevance and to exploit it as a tag for therapeutic and diagnostic applications.
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biosynthetic modulation of sialic acid dependent virus receptor interactions of two primate polyoma viruses
Journal of Biological Chemistry, 1995Co-Authors: Oliver T Keppler, Holger Kayser, Detlef Grunow, Werner Reutter, Peer Stehling, M Herrmann, Michael PawlitaAbstract:Abstract Sialic acids are essential components of the cell surface receptors of many microorganisms including viruses. A synthetic, N-substituted D-Mannosamine derivative has been shown to act as precursor for structurally altered sialic acid incorporated into glycoconjugates in vivo (Kayser, H., Zeitler, R., Kannicht, C., Grunow, D., Nuck, R., and Reutter, W.(1992) J. Biol. Chem. 267, 16934-16938). In this study we have analyzed the potential of three different sialic acid precursor analogues to modulate sialic acid-dependent virus receptor function on different cells. We show that treatment with these D-Mannosamine derivatives can result in the structural modification of about 50% of total cellular sialic acid content. Treatment interfered drastically and specifically with sialic acid-dependent infection of two distinct primate polyoma viruses. Both inhibition (over 95%) and enhancement (up to 7-fold) of virus binding and infection were observed depending on the N-acyl substitution at the C-5 position of sialic acid. These effects were attributed to the synthesis of metabolically modified, sialylated virus receptors, carrying elongated N-acyl groups, with altered binding affinities for virus particles. Thus, the principle of biosynthetic modification of sialic acid by application of appropriate sialic acid precursors to tissue culture or in vivo offers new means to specifically influence sialic acid-dependent ligand-receptor interactions and could be a potent tool to further clarify the biological functions of sialic acid, in particular its N-acyl side chain.
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biosynthesis of a nonphysiological sialic acid in different rat organs using n propanoyl d hexosamines as precursors
Journal of Biological Chemistry, 1992Co-Authors: Holger Kayser, Reinhard Zeitler, Rolf Nuck, Detlef Grunow, Christoph Kannicht, Werner ReutterAbstract:Abstract In this study it could be shown that in rat the normally occurring N-acetyl neuraminic acid can be modified in its N-acyl moiety by in vivo administration of the chemically synthesized N-propanoyl precursors, N-propanoyl-D-glucosamine or N-propanoyl-D-Mannosamine. It could be shown that each of these nonphysiological amino sugar analogues was incorporated into both membrane and serum glycoproteins. After treatment of rats with radiolabeled N-[acyl-1-14C]D-Mannosamine, radioactivity could be removed from serum glycoprotein fractions by incubation with neuraminidase from Clostridium perfringens or from Arthrobacter ureafaciens. Mild acid hydrolysis removed 98% of the radioactivity after in vivo labeling with N-[acetyl-1-14C]D-Mannosamine and 86% after labeling with N-[propanoyl-1-14C]D-Mannosamine. Chromatographic analysis yielded two compounds, i.e. N-acetyl neuraminic acid and N-propanoyl neuraminic acid, the latter being identified by gas liquid chromatography/mass spectrometry studies. Measurement of protein-bound radioactivity in different rat organs revealed a different organotropy of the natural and the nonphysiological neuraminic acid precursor. Of the glucosamine derivatives, N-acetyl-D-glucosamine showed the higher rate of uptake and incorporation in most organs (except in the submandibulary gland), and especially in kidney cortex and Morris hepatoma 7777. Natural and the unphysiological Mannosamine derivatives were incorporated at similar rates, except in liver, where N-acetyl-D-Mannosamine was taken up and metabolized more effectively. This finding indicates that it is possible to modify the acyl group of N-acetyl neuraminic acid in vivo by the introduction of an N-propanoyl group and possibly other homologous N-acyl groups. This procedure may provide a tool for a further characterization of the biological function of sialic acids.
Valentin Wittmann - One of the best experts on this subject based on the ideXlab platform.
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Cyclopropene derivatives of aminosugars for metabolic glycoengineering
Beilstein-Institut, 2019Co-Authors: Jessica Hassenrück, Valentin WittmannAbstract:Cyclopropenes have been proven valuable chemical reporter groups for metabolic glycoengineering (MGE). They readily react with tetrazines in an inverse electron-demand Diels–Alder (DAinv) reaction, a prime example of a bioorthogonal ligation reaction, allowing their visualization in biological systems. Here, we present a comparative study of six cyclopropene-modified hexosamine derivatives and their suitability for MGE. Three Mannosamine derivatives in which the cyclopropene moiety is attached to the sugar by either an amide or a carbamate linkage and that differ by the presence or absence of a stabilizing methyl group at the double bond have been examined. We determined their DAinv reaction kinetics and their labeling intensities after metabolic incorporation. To determine the efficiencies by which the derivatives are metabolized to sialic acids, we synthesized and investigated the corresponding cyclopropane derivatives because cyclopropenes are not stable under the analysis conditions. From these experiments, it became obvious that N-(cycloprop-2-en-1-ylcarbonyl)-modified (Cp-modified) Mannosamine has the highest metabolic acceptance. However, carbamate-linked N-(2-methylcycloprop-2-en-1-ylmethyloxycarbonyl)-modified (Cyoc-modified) Mannosamine despite its lower metabolic acceptance results in the same cell-surface labeling intensity due to its superior reactivity in the DAinv reaction. Based on the high incorporation efficiency of the Cp derivative we synthesized and investigated two new Cp-modified glucosamine and galactosamine derivatives. Both compounds lead to comparable, distinct cell-surface staining after MGE. We further found that the amide-linked Cp-modified glucosamine derivative but not the Cyoc-modified glucosamine is metabolically converted to the corresponding sialic acid
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rapid labeling of metabolically engineered cell surface glycoconjugates with a carbamate linked cyclopropene reporter
Bioconjugate Chemistry, 2014Co-Authors: Annekatrin Spate, Holger Buskamp, Andrea Niederwieser, Verena F Schart, Andreas Marx, Valentin WittmannAbstract:Metabolic oligosaccharide engineering is a valuable tool to monitor cellular carbohydrates. Here, we report the synthesis of a novel N-acyl-Mannosamine derivative bearing a methylcyclopropene tag that is attached to the sugar via a carbamate moiety. This derivative undergoes rapid Diels–Alder reaction with inverse electron demand. We demonstrate that the cell’s biosynthetic machinery incorporates this non-natural Mannosamine derivative into glycoconjugates that can, subsequently, be labeled within less than 10 min with a new sulfo-Cy3–tetrazine conjugate. Using this tetrazine-dye conjugate for the detection of the methylcyclopropene-tagged Mannosamine derivative, we could achieve dual labeling of two different metabolically incorporated sugars combining a Diels–Alder reaction with inverse electron demand and a strain-promoted azide–alkyne cycloaddition which are carried out simultaneously in a single step.
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Rapid Labeling of Metabolically Engineered Cell-Surface Glycoconjugates with a Carbamate-Linked Cyclopropene Reporter
2014Co-Authors: Anne-katrin Späte, Andrea Niederwieser, Verena F Schart, Andreas Marx, Holger Bußkamp, Valentin WittmannAbstract:Metabolic oligosaccharide engineering is a valuable tool to monitor cellular carbohydrates. Here, we report the synthesis of a novel N-acyl-Mannosamine derivative bearing a methylcyclopropene tag that is attached to the sugar via a carbamate moiety. This derivative undergoes rapid Diels–Alder reaction with inverse electron demand. We demonstrate that the cell’s biosynthetic machinery incorporates this non-natural Mannosamine derivative into glycoconjugates that can, subsequently, be labeled within less than 10 min with a new sulfo-Cy3–tetrazine conjugate. Using this tetrazine-dye conjugate for the detection of the methylcyclopropene-tagged Mannosamine derivative, we could achieve dual labeling of two different metabolically incorporated sugars combining a Diels–Alder reaction with inverse electron demand and a strain-promoted azide–alkyne cycloaddition which are carried out simultaneously in a single step
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Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions
Beilstein-Institut, 2014Co-Authors: Annekatrin Spate, Andrea Niederwieser, Verena F Schart, Julia Häfner, Thomas U. Mayer, Valentin WittmannAbstract:Monitoring glycoconjugates has been tremendously facilitated by the development of metabolic oligosaccharide engineering. Recently, the inverse-electron-demand Diels–Alder reaction between methylcyclopropene tags and tetrazines has become a popular ligation reaction due to the small size and high reactivity of cyclopropene tags. Attaching the cyclopropene tag to Mannosamine via a carbamate linkage has made the reaction even more efficient. Here, we expand the application of cyclopropene tags to N-acylgalactosamine and N-acylglucosamine derivatives enabling the visualization of mucin-type O-glycoproteins and O-GlcNAcylated proteins through Diels–Alder chemistry. Whereas the previously reported cyclopropene-labeled N-acylMannosamine derivative leads to significantly higher fluorescence staining of cell-surface glycoconjugates, the glucosamine derivative gave higher labeling efficiency with protein preparations containing also intracellular proteins
Chun-fan Chen - One of the best experts on this subject based on the ideXlab platform.
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Phosphate-catalyzed epimerization of N-acetyl-d-glucosamine to N-acetyl-d-Mannosamine for the synthesis of N-acetylneuraminic acid
Journal of The Taiwan Institute of Chemical Engineers, 2016Co-Authors: Chun-fan ChenAbstract:Abstract Phosphate-catalyzed epimerization of N -acetyl- d -glucosamine to N -acetyl- d -Mannosamine is reported in this study. The epimerization of N -acetyl- d -glucosamine was found to be facilitated by proton acceptors via the deprotonation of the amide group. Among the proton acceptors tested in this study phosphate exhibited the highest epimerization activity due to its nucleophilicity and its ability in promoting ring-opening reaction. The standard free energy change and standard enthalpy change for the epimerization of N -acetyl- d -glucosamine to N -acetyl- d -Mannosamine are +2.32 kJ/mole and +1.83 kJ/mole, respectively. Based on the Arrhenius equation, the activation energy of the phosphate-catalyzed epimerization was estimated as 56.36 ± 2.89 kJ/mole. At 80 °C, the initial rate of the phosphate-catalyzed epimerization, 19.70 mM/h, was more than 47-fold that of the control. Under the optimal conditions, the phosphate-catalyzed epimerization reached equilibrium with a conversion of 0.316 within 7 h, comparable with a conversion of 0.284 after 70 min for the epimerase-catalyzed reaction. Due to its compatibility with the subsequent enzyme reaction, it is possible to conduct the phosphate-catalyzed epimerization and the lyase-catalyzed biotransformation in one single bioreactor for the quantitative transformation of N -acetyl- d -glucosamine to N -acetylneuraminic acid.
Oliver T Keppler - One of the best experts on this subject based on the ideXlab platform.
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biochemical engineering of the n acyl side chain of sialic acid biological implications
Glycobiology, 2001Co-Authors: Oliver T Keppler, Michael Pawlita, Rudiger Horstkorte, Carolin Schmidt, Werner ReutterAbstract:: N-Acetylneuraminic acid is the most prominent sialic acid in eukaryotes. The structural diversity of sialic acid is exploited by viruses, bacteria, and toxins and by the sialoglycoproteins and sialoglycolipids involved in cell-cell recognition in their highly specific recognition and binding to cellular receptors. The physiological precursor of all sialic acids is N-acetyl D-Mannosamine (ManNAc). By recent findings it could be shown that synthetic N-acyl-modified D-Mannosamines can be taken up by cells and efficiently metabolized to the respective N-acyl-modified neuraminic acids in vitro and in vivo. Successfully employed D-Mannosamines with modified N-acyl side chains include N-propanoyl- (ManNProp), N-butanoyl- (ManNBut)-, N-pentanoyl- (ManNPent), N-hexanoyl- (ManNHex), N-crotonoyl- (ManNCrot), N-levulinoyl- (ManNLev), N-glycolyl- (ManNGc), and N-azidoacetyl D-Mannosamine (ManNAc-azido). All of these compounds are metabolized by the promiscuous sialic acid biosynthetic pathway and are incorporated into cell surface sialoglycoconjugates replacing in a cell type-specific manner 10-85% of normal sialic acids. Application of these compounds to different biological systems has revealed important and unexpected functions of the N-acyl side chain of sialic acids, including its crucial role for the interaction of different viruses with their sialylated host cell receptors. Also, treatment with ManNProp, which contains only one additional methylene group compared to the physiological precursor ManNAc, induced proliferation of astrocytes, microglia, and peripheral T-lymphocytes. Unique, chemically reactive ketone and azido groups can be introduced biosynthetically into cell surface sialoglycans using N-acyl-modified sialic acid precursors, a process offering a variety of applications including the generation of artificial cellular receptors for viral gene delivery. This group of novel sialic acid precursors enabled studies on sialic acid modifications on the surface of living cells and has improved our understanding of carbohydrate receptors in their native environment. The biochemical engineering of the side chain of sialic acid offers new tools to study its biological relevance and to exploit it as a tag for therapeutic and diagnostic applications.
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biosynthetic modulation of sialic acid dependent virus receptor interactions of two primate polyoma viruses
Journal of Biological Chemistry, 1995Co-Authors: Oliver T Keppler, Holger Kayser, Detlef Grunow, Werner Reutter, Peer Stehling, M Herrmann, Michael PawlitaAbstract:Abstract Sialic acids are essential components of the cell surface receptors of many microorganisms including viruses. A synthetic, N-substituted D-Mannosamine derivative has been shown to act as precursor for structurally altered sialic acid incorporated into glycoconjugates in vivo (Kayser, H., Zeitler, R., Kannicht, C., Grunow, D., Nuck, R., and Reutter, W.(1992) J. Biol. Chem. 267, 16934-16938). In this study we have analyzed the potential of three different sialic acid precursor analogues to modulate sialic acid-dependent virus receptor function on different cells. We show that treatment with these D-Mannosamine derivatives can result in the structural modification of about 50% of total cellular sialic acid content. Treatment interfered drastically and specifically with sialic acid-dependent infection of two distinct primate polyoma viruses. Both inhibition (over 95%) and enhancement (up to 7-fold) of virus binding and infection were observed depending on the N-acyl substitution at the C-5 position of sialic acid. These effects were attributed to the synthesis of metabolically modified, sialylated virus receptors, carrying elongated N-acyl groups, with altered binding affinities for virus particles. Thus, the principle of biosynthetic modification of sialic acid by application of appropriate sialic acid precursors to tissue culture or in vivo offers new means to specifically influence sialic acid-dependent ligand-receptor interactions and could be a potent tool to further clarify the biological functions of sialic acid, in particular its N-acyl side chain.
Zhongwu Guo - One of the best experts on this subject based on the ideXlab platform.
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efficient glycoengineering of gm3 on melanoma cell and monoclonal antibody mediated selective killing of the glycoengineered cancer cell
Bioorganic & Medicinal Chemistry, 2007Co-Authors: Qianli Wang, Junping Zhang, Zhongwu GuoAbstract:Abstract To verify the principal of a new immunotherapeutic strategy for cancer, a monoclonal antibody 2H3 against N -phenylacetyl GM3, an unnatural form of the tumor-associated antigen GM3, was prepared and employed to demonstrate that murine melanoma cell B16F0 could be effectively glycoengineered by N -phenylacetyl- d -Mannosamine to express N -phenylacetyl GM3 and that 2H3 was highly cytotoxic to the glycoengineered B16F0 cell in the presence of complements. It was further demonstrated that B16F0 cell could be glycoengineered 4–5 times more effectively than 3T3 A31 cell, a normal murine embryo fibroblast cell, and that the antibody and complement mediated cytotoxicity was at least 200 times more potent to the glycoengineered B16F0 cell than to the N -phenylacetyl- d -Mannosamine-treated 3T3 A31 cell. These results show the promise for developing useful melanoma immunotherapies based on vaccination against N -phenylacetyl GM3 followed by treatment with N -phenylacetyl- d -Mannosamine.
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efficient metabolic engineering of gm3 on tumor cells by n phenylacetyl d Mannosamine
Biochemistry, 2006Co-Authors: Peter J Chefalo, Zhongwu Guo, Yanbin Pan, Nancy Nagy, Clifford V HardingAbstract:Abnormal carbohydrates expressed on tumor cells, which are termed tumor-associated carbohydrate antigens (TACAs), are potential targets for the development of cancer vaccines. However, immune tolerance to TACAs has severely hindered progress in this area. To overcome this problem, we have developed a novel immunotherapeutic strategy based on synthetic cancer vaccines and metabolic engineering of TACAs on tumor cells. One critical step of this new strategy is metabolic engineering of cancer, namely, to induce expression of an artificial form of a TACA by supplying tumors with an artificial monosaccharide precursor. To identify the proper precursor for this application, N-propionyl, N-butanoyl, N-isobutanoyl, and N-phenylacetyl derivatives of d-Mannosamine were synthesized, and their efficiency as biosynthetic precursors in modifying sialic acid and inducing expression of modified forms of GM3 antigen on tumor cells was investigated. For this purpose, tumor cells were incubated with different N-acyl-d-manno...
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Biochemical Engineering of Surface α2–8 Polysialic Acid for Immunotargeting Tumor Cells
The Journal of biological chemistry, 2000Co-Authors: Tianmin Liu, Zhongwu Guo, Qingling Yang, Subash Sad, Harold J. JenningsAbstract:To target tumor cells for immunotherapy, we evaluated the feasibility of altering the epitopes on the surface polysialic acid of tumor cells. A precursor (N-propionylMannosamine), when incubated with leukemic cells, RBL-2H3 and RMA, resulted in substitution of the N-acetyl groups of surface alpha2-8 polysialic acid with N-propionyl groups. Expression of the altered alpha2-8 N-propionylpolysialic acid on the surface of tumor cells induced their susceptibility to cell death mediated by monoclonal antibody 13D9 (mAb 13D9), which specifically recognizes alpha2-8 N-propionylated polysialic acid. The expression of alpha2-8 N-propionylated polysialic acid and the lysis of tumor cells by antibody-dependent cytotoxicity depended on the time and dose of incorporation of N-propionylated Mannosamine. In vivo, mAb 13D9 effectively controlled metastasis of leukemic cells RMA when mice were administered the precursor N-propionylated Mannosamine.