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  • 1
    ISSN: 0947-3440
    Schlagwort(e): Carbohydrates ; Saccharides ; Trichloroacetimidates ; Glycosyltransferases ; Enzymes ; Transferases ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Building Units of Oligosaccharides, CX.  -  Synthesis of Potential Inhibitors of N-Acetylglucosaminyltransferase IModified derivatives of the trisaccharide octyl α-D-Man-(1→3)-[α-D-Man(1→6)]-β-D-Man were synthesized by attaching reactive groups via a pentyl spacer to the 4′-OH and 6′-OH group. Glycosylation steps were carried out by using the trichloroacetimidate method with suitable building blocks. The compounds substituted at 6′-OH are of special interest. The epoxide 27 and the diazirine 25 are reversible inhibitors of N-acetylglucosaminyltransferase I (GlcNAc-T I). Product 26 with a spacer-linked iodoacetamide is an irreversible inhibitor of GlcNAc-T I.
    Materialart: Digitale Medien
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  • 2
    ISSN: 0947-3440
    Schlagwort(e): Carbohydrates ; Saccharides ; Glycosyltransferases ; Trichloroacetimidates ; Transferases ; Enzymes ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Building Units of Oligosaccharides, CIX.  -  Synthesis of Modified Oligosaccharides of N-Glycoproteins for Substrate Specificity Studies of N-Acetylglucosaminyltransferase IA series of modified derivatives of the trisaccharide octyl α-D-Man(1→3)-[α-D-Man(1→6)]-β-D-Man were synthesized for substrate specificity studies of N-acetylglucosaminyltransferase I (GlcNAc-T I). The hydroxyl groups at C-3, C-4 and C-6 of the α(1→3)-linked Mannose were replaced by hydrogen and methoxy groups. At the α(1→6)-linked mannose the hydroxyl group at C-2 was deoxygenated and the hydroxyl groups at C-3, C-4 and C-6 were replaced by methoxy groups. The syntheses of the ten trisaccharides were carried out by the interchangeable combination of modified building blocks. The trichloroacetimidate method was favourable for all glycosylation steps.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 1113-1126 
    ISSN: 0170-2041
    Schlagwort(e): Heptose oligosaccharides ; Kdo oligosaccharides ; Lipopolysaccharides ; Carbohydrates ; Oligosaccharides ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Building Units of Oligosaccharides, XCVIII. - Synthesis of Oligosaccharides of the Inner Core and Lipoid A Region of LipopolysaccharidesGlycosidic coupling of the Hep-Kdo disaccharide bromide 9 with the Lipoid A analogous disaccharide 10 gives the tetrasaccharide 11 which was deprotected to yield the tetrasaccharide L-α-D-Hepp-(1→5)-α-Kdop-(2→6)-β-D-GlcpNhm-(1→6)-D-GlcNhm (18). In a further block synthesis 10 was glycosylated with the Hep-[Kdo]-Kdo donor 24. Deprotection of the corresponding pentasaccharide 25 furnished L-α-D-Hepp-(1→5)-[α-Kdop]-(2→4)-α-Kdop-(2→6)-β-D-GlcpNhm-(1→6)-D-GlcNhm (31). Sheep erythrocytes can be coated with these oligosaccharides 18 and 31. The resulting complexes are used as synthetic antigens and immunogens containing the disaccharide L-α-D-Hepp-(1→5)-α-Kdop and the branched trisaccharide L-α-D-Hepp-[α-Kdop-(2→4)]-α-Kdo as antigenic determinants.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 655-663 
    ISSN: 0170-2041
    Schlagwort(e): Heptose oligosaccharides ; KDO oligosaccharides ; Lipopolysaccharides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Building Units of Oligosaccharides, XCII. - Synthesis of Trisaccharid Units of the Inner Core Region of LipopolysaccharidesL-glycero-D-manno-Heptose derivative 9 reacts with KDO-glycosyl acceptor 6 stereoselectively to give the α(1→5)-linked disaccharide 10. Coupling of now available KDO-glycosyl acceptor 12 with KDO bromide 2 leads to the branched α(2′→4)-α(1″→5)-linked trisaccharide 21. After removal of protecting groups in 10 and 21 3-deoxy-5-O-(L-glycero-α-D-manno-heptopyranosyl)-D-manno-2-octulopyranosonic acid (18) and 3-deoxy-4-O-(3-deoxy-α-D-manno-octulopyranosylonic acid)-5-O-(L-glycero-α-D-manno-heptopyranosyl)-D-manno-2-octulopyranosonic acid (27), respectively, are obtained.
    Notizen: Das L-glycero-D-manno-Heptose-Derivat 9 läßt sich stereoselektiv mit dem KDO-Glycosyl-Akzeptor 6 zu dem α(1→5)-glycosidisch verknüpften Disaccharid 10 umsetzen. Der hieraus erhältliche Akzeptor 12 wird mit dem KDO-Glycosyl-Donator 2 stereoselektiv zu dem verzweigten α(2′→4)-α(1″→5)-verknüpften Trisaccharid 21 umgesetzt. Nach der Entblockierung von 10 und 21 ist 3-Desoxy-5-O-(L-glycero-α-D-manno-heptopyransyl)-D-manno-2-octulopyranosonsäure (18) und 3-Desoxy-4-O-(3-desoxy-α-D-manno-octulopyranosylonsäure)-5-O-(L-glycero-α-D-manno-heptopyransyl)-D-manno-2-octulopyranosonsäure (27) zu erhalten.
    Materialart: Digitale Medien
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  • 5
    ISSN: 0170-2041
    Schlagwort(e): KDO oligosaccharides ; Lipoid A ; Lipopolysaccharides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Building Units of Oligosaccharides, XCIV. - Synthesis of KDO-Containing Tri- and Tetrasaccharide Sequences of the Inner Core and Lipoid A Region of LipopolysaccharidesThe glycosyl acceptor 18, who contains two glycosidically β(1→6) linked 2-amino-2-deoxy-D-glucose residues was synthesized. The two amino groups are acetylated with (R)-3-hydroxytetradecanoic acid. The 6′ position of 18 is suitable for selective glycosidation reactions. The reaction of the KDO bromide 21 with 18 yields the trisaccharide 22 which gives α-KDO-(2→6)-β-D-GlcNhm-(1→6)-D-GlcNhm (25) after deprotection. The substitution of 22 is changed into 27, which was coupled with the bromide 21 to yield the tetrasaccharide 29. Deprotection leads to the structure α-KDO-(2→4)-α-KDO-(2→6)-β-D-GlcNhm-(1→6)-D-GlcNhm (33). It is possible to coat sheep erythrocytes with 25 and 33, which now present the KDO residues in an immunogenic form.
    Notizen: Der Glycosyl-Akzeptor 18, mit zwei β-(1→6)-glycosidisch verknüpften 2-Amino-2-desoxy-D-glucose-Resten, dessen beide Amino-Gruppen mit (R)-3-Hydroxytetradecansäure acyliert sind, konnte synthetisiert werden. An der 6′-OH-Gruppe von 18 lassen sich selektiv Glycosidierugen durchführen. Die Anknüpfung des KDO-Bromids 21 an 18 ergibt das Trisaccharid 22, aus dem nach Entblockierung α-KDO-(2→6)-β-D-GlcNhm-(1→6)-D-GlcNhm (25) erhältlich ist. Die Kupplung des aus 22 erhältlichen 27 mit dem KDO-Bromid 21 ergibt ein Tetrasaccharid 29, bei dem die Entblockierung zum α-KDO-(2→4)-α-KDO-(2→6)-β-D-Glc-Nhm-(1→6)-D-GlcNhm (33) führt. Sowohl 25 wie 33 können auf Schafs-Erythrozyten aufgezogen werden und enthalten die KDO-Reste dann in immunogener Form.
    Materialart: Digitale Medien
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  • 6
    ISSN: 0170-2041
    Schlagwort(e): Heptose oligosaccharides ; Kdo oligosaccharides ; Lipopolysaccharides ; Antigens, synthetic ; Oligosaccharides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Building Units of Oligosaccharides, IC. - Preparation of Synthetic Antigens of the Inner Core Region of Lipopolysaccharides by Copolymerisation with AcrylamideBesides L-α-D-Hepp-OAll (5), the following allyl glycosides with oligosaccharide structures of the inner core region of lipopolysaccharides have been synthesized: L-α-D-Hepp-(1→7)-L-α-D-Hepp-OAll (19), L-α-D-Hepp-(1→3)-L-α-D-Hepp-OAll (26), L-α-D-Hepp-(1→5)-α-Kdop-OAll (31), L-α-D-Hepp-(1→5)-β-Kdop-OAll (34), L-α-D-Hepp-(1→5)-[α-Kdop-(2→4)]-α-Kdop-OAll (48) and L-α-D-Hepp-(1→5)-[α-Kdop-(2→4)]-β-Kdop-OAll (39). All these compounds have been coupled with cysteamine to the spacer-elongated derivatives 54b - 60b and finally converted into the acryloyl compounds 54c - 60c. The copolymerisation of 54c - 60c with acrylamide gave the polymers 54d - 60d, containing the above mentioned oligosaccharides as haptens in an antigenic form.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 487-495 
    ISSN: 0170-2041
    Schlagwort(e): Carbohydrates ; C-Glycosides ; N-Acetylneuraminic acid ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of C-Glycosides of N-Acetylneuraminic Acid and Other DerivativesReaction of the β-pyranosyl chloride 1 of N-acetylneuraminic acid with allyl(tributyl)stannane under radical-induced conditions affords a mixture of the allyl C-glycosides 2/3. After deprotection, the pure allyl α-C-glycoside 5 and the analogous β isomer 7 can be isolated. The allyl C-glycosides 2 and 3 are converted into the corresponding epoxypropyl C-glycosides 9 and 11 by epoxidation of the allylic group. Further modified allyl C-glycosides are prepared from the C-3-hydroxylated N-acetylneuraminic acid, which are available as pure α- and β-C-glycosides 19 and 21 after deprotection. At C-3 modified compounds are also synthesized which have allyl and azido residues at C-3. All compounds are interesting as potential inhibitors of sialidases, CMP sialate syntheses, and viral infection.
    Materialart: Digitale Medien
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  • 8
    ISSN: 0170-2041
    Schlagwort(e): Carbohydrates ; Oligosaccharides ; N-Glycoproteins ; N-Acetylglucosaminyltransferases ; Enzymes ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Building Units of Oligosaccharides, CI.  -  Synthesis of Modified Oligosaccharides of the N-Glycoproteins Intended for Substrate Specificity Studies of N-Acetylglucosaminyltransferase II of the Trimming ProcessThe trichloroacetimidate method was very successful for the synthesis of the tetrasaccharide octyl O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→2)-O-(α-D-mannopyranosyl)-(1→3)-O-[(α-D-mannopyranosyl)-(1→6)]-β-D-mannopyranoside (10). Further derivatives of the tetrasaccharide with a 4-O-methyl group 20 and with a 4-deoxy group 28 were synthesized. The tetrasaccharides are intended for substrate specificity studies of the N-acetylglucosaminyltransferase II of the trimming process in the biosynthesis of N-glycoproteins.
    Materialart: Digitale Medien
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  • 9
    ISSN: 0170-2041
    Schlagwort(e): Deoxyfuconojirimycin ; Amino sugars ; Indolizidine derivatives ; Fucosidase inhibitors ; Carbohydrates ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Monosaccharides Containing Nitrogen in the Ring, XXXIX.  -  Synthesis of Analogues of 1,5-Dideoxy-1,5-imino-L-fucitol, Inhibitors of α-L-FucosidaseVariation of the side chain in the 1,3-dithiane derivative 1 of D-galactose leads to a series of analogues of 1,5-dideoxy-1,5-imino-L-fucitol (deoxyfuconojirimycin) (33), which are potent inhibitors of α-L-fucosidase. Cleavage of the dithioacetal in 5 followed by reduction of the aldehyde 6 and deblocking results in 1,5-dideoxy-1,5-imino-L-galactitol (8). The aldehyde 6 is converted by Wittig reaction to 10 and 14 via 9 and 13, which are homologues of 1,5-dideoxy-1,5-imino-L-fucitol (33). Cyclization of the Wittig product 15 yields the γ-lactam 18. After reduction of the acetylated γ-lactam 19 and subsequent deblocking the trihydroxyindolizidine 24 is obtained, which is an analogue of castanospermine with L-fuco configuration. The chloride 30, which is available from 27, can be converted by intramolecular substitution and removal of the blocking groups to the bicyclic aziridine derivative (3R,4S,5R,6S) -1-azabicyclo[4.1.0]heptane-3,4,5-triol (32). First results on the inhibitory activities of all new analogues on α-L-fucosidase are presented.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 29 (1990), S. 823-839 
    ISSN: 0570-0833
    Schlagwort(e): Core regions ; Carbohydrates ; Glycoproteins ; Proteins ; X-ray structure analysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The covalently bound carbohydrate moiety in glycoproteins can stabilize the protein molecule intramolecularly, or it may have an intermolecular function as receptor in biological recognition. The discovery of these biological phenomena has led to a renaissance of the chemistry and biochemistry of carbohydrates. Both N-glycoproteins as well as O-glycoproteins contain special, invariant oligosaccharide chains in the protein-binding region, which occur again in all glycoproteins, and are described as the “core regions.” This review describes the various methods of oligosaccharide synthesis that may be used to arrive at the basic core structures by chemical means. Methods of oligosaccharide synthesis have improved so much that it is possible to synthesize complex lactosamine-type structures, and “bisected”-type structures up to nona- and undecasaccharides respectively. Oligosaccharide chains are considerably less flexible than peptide chains. Using modern methods of NMR spectroscopy, their preferred solution conformation can readily be determined. In the case of one branched octasaccharide, a comparison of the conformations in solution and in the crystal is possible. Oligosaccharides may be linked to the amide group of an asparagine, or to the hydroxyl groups of serine or threonine. By using suitable protecting groups, the glycosyl amino acids obtained can be extended with further amino acids at the N- or C-terminus, thus arriving at the desired glycopeptide sequences. In the linkage region, glycopeptides prefer certain conformations. Future research into glycoprotein functions may involve the synthesis and biochemical study of modified glycoprotein segments.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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