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  • 1
    Electronic Resource
    Electronic Resource
    Structural variations of N-acetylneuraminic acid, part 19: Synthesis of both epimeric pairs of the 4-C-methyl- and 4-deoxy-4-C-methyl- as well as of the β-methylketoside of 4-deoxy-4-C-methylene-N-acetylneuraminic acid (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 111-125 
    Details
    ISSN: 1434-4475
    Keywords: Sialic acids ; Methyl-branched sugars ; Zirconium organyls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Während die Umsetzung des 4-Oxoderivates2 a mit (BuO)3 MeZr ausschließlich zur equatorialen 4-C-Methylverbindung3 a führt, wurde bei der Reaktion mitMe 4Zr ein 3:2-Gemisch der beiden Diastereomeren3 a und4 a erhalten. Das 4-C-Methylenderivat7 a wurde durch Reaktion derselben 4-Oxoverbindung mit CH2I2/Zn/Cp 2ZrCl2 erhalten. Eine anschließende Hydrierung (H2-Pd/C) führte zu einem trennbaren Germisch der beiden 4-Deoxy-4-C-methylderivative8 a und9 a. Diese Verbindungen konnten durch das Entfernen der Schutzgruppen einerseits in die 5-Acetamido-3,4,5-trideoxy-4-C-methyl-D-glycero-D-galacto-2-nonulosonsäure10 a und 5-Acetamido-2,7-anhydro-4-C-methyl-3,4,5-tridoxy-D-glycero-D-talo-2-nonulosonsäure11 a umgewandelt werden. Die Verbindungen Methyl-5-acetamido-4-C-methylen-3,4,5-trideoxy-β-D-manno-2-nonulopyranosidonat (15) und Methyl-5-acetemido-4-C-methyl-3,4,5-tridoxy-β-D-glycero-D-talo-2-nonulopyranosidonat (16) wurden als Modellverbindungen für enzymatische Untersuchungen über peracetylierte Zwischenstufen hergestellt. Überraschenderweise zeigte nur die 4-C-Methylenverbindung15 eine starke kompetitive Hemmung gegenüber CMP-Sialat-Synthase.
    Notes: Summary While the reaction of the 4-oxo-Neu 5 Ac derivative2 a with tributoxy methyl zirconate led exclusively to equatorial 4-C-methyl derivative3 a, the analogous reaction with tetramethyl zirconate yielded a 3:2 mixture of both diastereoisomeres3 a and4 a. After removal of protecting groups the 5-acetamido-3,4-dideoxy-4-C-methyl-D-glycero-D-galacto-2-nonulosonic acid5 a and 5-acetamido-3,4-dideoxy-4-C-methyl-D-glycero-D-talo-2-nonulosonic acid6 a were obtained. The 4-C-methylene derivative was prepared by treatment of the same 4-oxo-derivative with CH2I2/Zn/Cp 2ZrCl2. Subsequent hydrogenation led to both epimeric 4-deoxy-4-C-methyl derivatives8 a and9 a. Final removal of protecting groups gave the 5-acetamido-3,4,5-trideoxy-4-C-methyl-D-glycero-D-galacto-2-nonulosonic acid10 a respectively the 5-acetamido-2,7-anhydro-4-C-methyl-3,4,5-trideoxy-D-glycero-D-talo-2-nonulosonic acid11 a. The β-methylketosides of the 4-deoxy-4-C-methyl- (16) and 4-C-methylene-Neu 5 Ac (15) were prepared via the peracetylated derivatives to obtain modell substrates for enzymatic studies. Thus all free acids were tested for inhibition of CMP-sialate synthease. Only the 4-C-methylene compound15 showed most unexpectedly a strong competitive inhibition of this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00815172
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  • 2
    Electronic Resource
    Electronic Resource
    Solution conformation of the two alditols obtained by sodium borohydride reduction of N-acetylneuraminic acid (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 521-528 
    Details
    ISSN: 1434-4475
    Keywords: Alditols of sialic acid ; Conformations ; Molecular mechanics ; Nuclear magnetic resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei der Reduktion von N-Acetyl-Neuraminsäure mit Natriumborhydrid in wäßriger Lösung werden die Alditole1 und2 im Verhältnis 3:2 gebildet. Die stereochemische Zuordnung und die Konformation der beiden Epimere in Lösung wurden mit Hilfe einer NMR-Analyse durchgeführt. In Ergänzung dazu wurde die Anwendbarkeit von Rechnungen des Typus Molekulare Mechanik auf flexible Moleküle dieser Art untersucht und gefunden, daß Populationen von Konformationen, welche primär durch 1,3-diaxiale Wechselwirkungen determiniert sind, durch Rechnungen dieses Typs nicht vorhersagbar sind. In wäßriger Lösung liegt Verbindung2 in gestreckter Form vor. Die aus2 ableitbare α-N-Acetylneuraminsäure ähnliche Konformation, welche dem Substrat derClostridium perfringens-Lyase entspricht, ist um ⩾ 1 kcal energiereicher als die der gestreckten Form und liegt in Lösung nicht in meßbaren Mengen vor. Man kann erwarten, daß dieser Energiebeitrag unschwer bei der Einbettung in die Enzymtasche der Lyase aufgebracht werden kann.
    Notes: Abstract The stereochemistries and the conformations of the two alditols1 and2 (3:2) obtained upon reduction of N-acetylneuraminic acid were determined in aqueous solution using proton and carbon nuclear magnetic resonance spectroscopy. Molecular mechanics calculation was proved to be not applicable onto alditols, if the balance of the conformational equilibrium is maintained by 1,3-diaxial interactions. No measurable amount of the α-N-acetylneuraminic acid like triple bent alditol form, which is believed to be the substrate of theClostridium perfringens lyase, could be detected in solution. In aqueous solution compound2 is present in its extended form. One can expect that the necessary energy contribution of approximately 1 kcal to fold2 into the form which is recognized by the enzyme is easily available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809804
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  • 3
    Electronic Resource
    Electronic Resource
    Glycan structure of the S-layer glycoprotein ofBacillus sp. L420-91 (1995)
    Springer
    Glycoconjugate journal 12 (1995), S. 99-107 
    Details
    ISSN: 1573-4986
    Keywords: Eubacteria ; glycoprotein ; surface layer (S-layer) ; glycan structure ; 1H and13C-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Preliminary taxonomic characterization of isolate L420-91 has revealed that this organism is closely related to the speciesBacillus aneurinolyticus. The bacterium is covered by a squarely arranged crystalline surface layer composed of identical glycoprotein subunits with an apparent molecular mass in the range of 109 kDa. A total carbohydrate content of approximately 3.5% (wt/wt) was determined in the purified surface layer glycoprotein. Glycopeptides were obtained after exhaustive Pronase digestion and purification including gel filtration, ion exchange chromatography and HPLC. From the combined evidence of composition analysis, Smith degradation and nuclear magnetic resonance spectroscopy experiments we propose the following structure for the glycan chain of the surface layer glycoprotein: $$\begin{array}{*{20}c} { \to 3) - \alpha - D - Rhap - (1 \to 3) - \alpha - D - Rhap - (1 \to 2) - \alpha - D - Rhap - (1 \to 2) - \alpha - D - Rhap - (1 \to } \\ {\begin{array}{*{20}c} {\begin{array}{*{20}c} 2 \\ \uparrow \\ 1 \\ \end{array} } & {\begin{array}{*{20}c} 2 \\ \uparrow \\ 1 \\ \end{array} } \\ \end{array} } \\ {\alpha - D - Fucp3NAc \alpha - D - Fucp3NAc} \\ \end{array}$$
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00731875
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  • 4
    Electronic Resource
    Electronic Resource
    A pyrophosphate bridge links the pyruvate-containing secondary cell wall polymer of Paenibacillus alvei CCM 2051 to muramic acid (2000)
    Springer
    Glycoconjugate journal 17 (2000), S. 681-690 
    Details
    ISSN: 1573-4986
    Keywords: Paenibacillus alvei ; secondary cell wall polymer (SCWP) ; surface layer (S-layer) ; peptidoglycan ; NMR spectroscopy ; structure determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The peptidoglycan, the secondary cell wall polymer (SCWP), and the surface layer (S-layer) glycoprotein are the major glycosylated cell wall components of Paenibacillus alvei CCM 2051. In this report, the complete structure of the SCWP, its linkage to the peptidoglycan layer, and its physicochemical properties have been investigated. From the combined evidence of chemical and structural analyses together with one- and two-dimensional nuclear magnetic resonance spectroscopy, the following structure of the SCWP-peptidoglycan complex is proposed: [(Pyr4,6)-β-D-Manp NAc-(1→4)-β-D-Glcp NAc-(1→3)]ñ11-(Pyr4,6)-β-D-Manp NAc-(1→4)-α-D-Glcp NAc-(1→O)-PO2-O-PO2-(O→6)-MurNAc- Each disaccharide unit is substituted by 4,6-linked pyruvic acid residues. Under mild acidic conditions, up to 50% of them are lost, leaving non-substituted ManNAc residues. The anionic glycan chains constituting the SCWP are randomly linked via pyrophosphate groups to C-6 of muramic acid residues of the peptidoglycan layer. 31P NMR reveals two signals that, as a consequence of micelle formation, experience different line broadening. Therefore, their integral ratio deviates significantly from 1:1. By treatment with ethylenediaminetetraacetic acid, sodium dodecyl sulfate, and sonication immediately prior to NMR measurement, this ratio approaches unity. The reversibility of this behavior corroborates the presence of a pyrophosphate linker in this SCWP-peptidoglycan complex. In addition to the determination of the structure and linkage of the SCWP, a possible scenario for its biological function is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011062302889
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  • 5
    Electronic Resource
    Electronic Resource
    Strukturelle Abwandlungen an N-Acetylneuraminsäure, 5(1) Zur Transformation der Carboxylgruppe von N-Acetylneuraminsäure in die Tetrazol-Gruppe (1986)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1986 (1986), S. 2104-2111 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structural Transformations of N-Acetylneuraminic Acid, 5. - Transformation of the Carboxyl Group of N-Acetylneuraminic Acid into a Tetrazole GroupMethyl 5-(acetylamino)-3,5-didesoxy-β-D-Glycero-D-galacto-2-nonulopyranosidonic methyl ester (1) was tranformed into the corresponding amide 2, and the peracetylated 2a was converted with POCl3 into the nitrile derivative 3. The nitrile function reacts with ammonium azide to form 4 with a bioisosteric tetrazole function. After deprotection the anomeric mixture 5a/5b of the title compound was isolated in a ratio of 5:1. A special boat conformation for the paracetylated α form 5c is also described.
    Notes: Methyl-5-(acetylamino)-3,5-didesoxy-β-D-glycero-D-galacto-2-nonulopyranosidonsäure-methylester (1) wurde in das entsprechende Amid 2 umgewandelt und dessen Peracetylverbindung 2a mit POCl3 in das Nitril 3 übergeführt. Dieses kann mit Ammoniumazid direkt in das zur Carboxylgruppe bioisostere Tetrazol 4 umgeformt werden. Nach Abspaltung aller Schutzgruppen entsteht das Anomerengemisch 5a/5b der Titelverbindung im Verhältnis 5:1. Über eine spezielle Wannenkonformation der peracetylierten α-Form 5c wird ebenfalls berichtet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198619861205
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  • 6
    Electronic Resource
    Electronic Resource
    Structural Variations of N-Acetylneuraminic Acid, 7. Synthesis of the C-7-, C-8-, and C-7,8-Side Chain Epimers of 2-Deoxy-2,3-didehydro-N-acetylneuraminic Acid and Their Behaviour Towards Sialidase from Vibrio cholerae (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 781-786 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Strukturelle Abwandlungen an N-Acetylneuraminsäure, 7. - Synthese der C-7-, C-8- und C-7,8-Seitenketten-Epimeren von 2-Desoxy-2,3-didehydro-N-acetylneuraminsäure und ihr Verhalten gegenüber Sialidase aus Vibrio choleraeDie peracetylierten Methylester-Derivate von 7-epi-Neu5Ac (2a), 8-epi-Neu5Ac (3a) und 7,8-bis-epi-Neu5Ac (4a) wurden mit Trifluormethansulfonsäure-trimethylsilylester in die entsprechenden 2-Desoxy-2,3-didehydro-Derivate 2b-4b umgewandelt, wobei als Nebenprodukte auch die 4,5-Oxazolino-Abkömmlinge 5b und 6b gebildet wurden. Hydrolyse von 2b-4b führte zu den freien Säuren 7-epi-Neu5Ac2en (2c), 8-epi-Neu5Ac2en (3c) and 7,8-bis-epi-Neu5Ac2en (4c). Diese inhibieren die Hydrolyse von 4-Methylumbelliferyl-α-Neu5Ac durch Vibrio-cholerae-Sialidase in einem signifikant unterschiedlichen Ausmaß. Dieses Verhalten war der Anlaß zur Konformationsanalyse von 2c-4c und auch von der schon lange bekannten 2-Desoxy-2,3-didehydro-N-acetylneuraminsäure (Neu5Ac2en) (1c). Es konnte ein signifikanter Zusammenhang zwischen den sehr charakteristisch aussehenden Profilen der α-Seite und deren Einfluß auf die Enzymreaktion festgestellt werden.
    Notes: The peracetylated methyl ester derivatives of 7-epi-Neu5Ac (2a), 8-epi-Neu5Ac (3a), and 7,8-bis-epi-Neu5Ac (4a) were transformed by trimethylsilyl trifluoromethanesulfonate into the corresponding 2-deoxy-2,3-didehydro derivatives 2b-4b. As minor products the 4,5-oxazolino derivatives 5b and 6b are formed. Hydrolysis of 2b-4b yields the free acids 7-epi-Neu5Ac2ene (2c), 8-epi-Neu5Ac2ene (3c), and 7,8-bis-epi-Neu5Ac2ene (4c). These show significantly different inhibitory influences on the hydrolysis of 4-methylumbelliferyl-α-Neu5Ac by Vibrio cholerae sialidase. This was the reason for establishing the conformation of 2c-4c and of the well-known 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2ene) (1c). A significant relationship between the characteristic profiles of the α-side of 1c-4c and the influence on the enzyme reaction was found.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870828
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  • 7
    Electronic Resource
    Electronic Resource
    Structural variations of N-acetylneuraminic acid, 15. Synthesis of 9-deoxy-, 7,9-dideoxy-, and 4,7,9-trideoxy-N-acetylneuraminic acid and their behaviour towards CMP-sialate synthase (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 93-97 
    Details
    ISSN: 0170-2041
    Keywords: CMP-sialate synthase ; Sialic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methyl ester of N-acetylneuraminic acid β-methyl ketoside (Neu5Ac1Me-2β-Me) (1) is used as common starting material for the synthesis of the title compounds. Combined derivatization reactions with reagents thiophosgene, p-cresol, benzoyl chloride, and acetic anhydride/pyridine lead to the thiocarbonate derivatives 2, 6-8, and 12. Further transformation with iodomethane yields the 9-iodo compounds 3, 9, and 13, which are reduced by tributyltin hydride to the deoxy derivatives 4, 10, and 14. Hydrolysis of 14, 10, and 4 affords the desired 9-deoxy, 7,9-dideoxy-, and 4,7,9-trideoxy-N-acetylneuraminic acids 15 (9-d-Neu5Ac), 11 (7,9-d2-Neu5Ac), and 5 (4,7,9-d3-Neu5Ac), respectively.  -  The sialic acid analogues 11 and 5 were activated by CMP-sialate synthase [E,C.2.7.7.43] to an extent of 30-40 and 50-60%, respectively, relative to N-acetylneuraminic acid.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900113
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  • 8
    Electronic Resource
    Electronic Resource
    Structural variations of N-acetylneuraminic acid, 14. Synthesis of the β-methyl ketosides of 4-oxo-, 7-oxo-, and 8-oxo-N-acetylneuraminic acid and the corresponding 7,7- and 8,8-dimethoxy derivatives their behaviour towards CMP-sialate synthase (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 83-91 
    Details
    ISSN: 0170-2041
    Keywords: CMP-sialate synthase ; Sialic acids ; N-Acetylneuraminic acid derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 4-, 7-, and 8-oxo-sialic acid β-methyl ketosides 7, 10a, and 11a were obtained by transformation of easily available derivatives of N-acetylneuraminic acid (1a). The carbonyl migration from C-7 to C-8 can be carried out under well-defined conditions with formation of the ketone 11b. Starting from 7- and 8-ketones 17 and 20 the corresponding dimethyl acetals are prepared. The 4-ketone 7 behaves as a moderate competitive inhibitor of CMP-sialate synthase [EC 2.7.7.43], whereas the 8-ketone 11a, the 8,8-dimethyl acetal 19, and the 7,7-dimethyl acetal 23 prove not to be inhibitors of this enzyme. The 7-ketone 10a was not tested because of instability under test conditions at pH 8.5.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900112
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  • 9
    Electronic Resource
    Electronic Resource
    Structural Variations of N-Acetylneuraminic Acid, 10. Synthesis of 2,7-, 2,8-, and 2,9-Dideoxy- and 2,4,7-Trideoxy-2,3-didehydro-N-acetylneuraminic Acids and Their Behavior Towards Sialidase from Vibrio cholerae (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 159-165 
    Details
    ISSN: 0170-2041
    Keywords: N-Acetylneuraminic acid ; Sialidase ; Vibrio cholerae ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Strukturelle Abwandlungen an N-Acetylneuraminsäure, 101). - Synthese von 2,7-, 2,8- und 2,9-Didesoxy- und 2,4,7-Tridesoxy-2,3-didehydro-N-acetylneuraminsäure und ihr Verhalten gegenüber Sialidase aus Vibrio choleraeDie peracetylierten Methylester-Derivate von 7-Desoxy-Neu5Ac (2c), 8-Desoxy-Neu5Ac (3a), 9-Desoxy-Neu5Ac (4a) und 4,7-Didesoxy-Neu5Ac (5a) wurden mit Trifluormethansulfonsäuretrimethylsilylester in die entsprechenden 2-Desoxy-2,3-didehydro-Derivate 2b-5b umgewandelt, wobei auch in wechselnder Menge die 4,5-Oxazolino-Abkömmlinge 6b-8b gebildet wurden. Hydrolyse von 2b-5b führte zu den freien Säuren 7-Desoxy-Neu5Ac2en (2c), 8-Desoxy-Neu5Ac2en (3c), 9-Desoxy-Neu5Ac2en (4c) und 4,7-Didesoxy-Neu5Ac2en (5c). Diese hemmen die Hydrolyse von 4-Methylumbelliferyl-α-Neu5Ac durch Sialidase aus Vibrio cholerae in einem signifikant unterschiedlichen Ausmaß. Der Vergleich ihrer ermittelten α-Seitenprofile mit demjenigen von Neu5Ac2en ermöglicht ein Verständnis für den sehr unterschiedlichen Einfluß auf die Enzymreaktion.
    Notes: The peracetylated methyl ester derivatives of 7-deoxy-Neu5Ac (2a), 8-deoxy-Neu5Ac (3a, 9-deoxy-Neu5Ac (4a), and 4,7-dideoxy-Neu5Ac (5a) were transformed by trimethylsilyl trifluoromethanesulfonate into the corresponding 2-deoxy-2,3-didehydro derivatives 2b-5b. As additional products, the 4,5-oxazolino derivatives 6b-8b were formed. Hydrolysis of 2b-5b yielded the free acids 7-deoxy-Neu5Ac2en (2c), 8-deoxy-Neu5Ac2en (3c), 9-deoxy-Neu5Ac2en (4c), and 4,7-dideoxy-Neu5Ac2en (5c). They showed significantly different inhibitory influences on the hydrolysis of 4-methylumbelliferyl-α-Neu5Ac by sialidase from Vibrio cholerae. The comparison of their evaluated α-side profiles with that of Neu5Ac2en (1c) enables a suitable explanation of their different inhibitory potencies.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890131
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