Conformational analysis of key disaccharide components of Brucella A and M antigens

The synthetic α 1,2 and α 1,3 disaccharide methyl glycosides of 4-amino-4,6-dideoxy-D-mannose 1–6 that constitute key structural elements of Brucella A and M antigens were analyzed by 1H and 13C nuclear magnetic resonance spectroscopy. A detailed conformational analysis was performed for the N-acetylated derivatives 1 and 4 as well as for the amino derivatives 2 and 5. Potential energy calculations using the GESA program established the global minima for the disaccharides 1, 2, 4, and 5, and mapped the energy surface as a function of the glycosidic torsion angles [Formula: see text] and ψ. Ensemble averaged nuclear Overhauser enhancements, weighted according to the Boltzmann distribution function, were derived for each of the four disaccharides. This procedure improved the fit between experimentally and theoretically derived nOe values, when compared to interpretations based on a single conformer model. The Brucella A and M antigens are homopolymers of 4-formamido-4,6-dideoxy-D-mannose and, as.N-formyl groups (saccharides 3, 6, and 8) are essential for the binding of these antigens to their respective antibodies, amide conformation was analyzed by examination of the vicinal proton–proton and proton–carbon coupling constants of the model monosaccharide 8. The conformational properties of the model compounds 1–8 were used to model the Brucella A and M polysaccharide antigens. Keywords: conformational analysis, disaccharide conformation, nuclear Overhauser measurements, molecular modeling, Brucella antigen.

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The conformational analysis of leukotriene D4 in aqueous solution based on high-field nuclear magnetic resonance measurements

Canadian Journal of Chemistry ◽

10.1139/v84-281 ◽

1984 ◽

Vol 62 (8) ◽

pp. 1640-1645 ◽

Cited By ~ 5

Author(s):

Makiko Sugiura ◽

Helmut Beierbeck ◽

George Kotovych ◽

Patrice C. Bélanger

Keyword(s):

Conformational Analysis ◽

Nuclear Overhauser Effect ◽

Relaxation Times ◽

Coupling Constants ◽

Leukotriene D4 ◽

Proton Proton ◽

Proton Coupling ◽

Overhauser Effect ◽

Vicinal Proton ◽

Nuclear Overhauser

The conformational analysis of LTD4 in D2O was carried out based on the analysis of vicinal proton–proton coupling constants, nonselective proton longitudinal relaxation times, and nuclear Overhauser effect data. The H6—C6 to C12 region of the molecule is transoid, the predominant rotamer about C5—C6 is gauche, and two rotamers can be used to describe the rotation about C12—C13. There are three rotamers that can be used to describe the rotation about the C21—C22 bond of cysteine. Finally, chelation between an Yb3+, shift reagents and LTD4 was not observed.

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Conformation of purine mononucleotides by H{H} and P{H} nuclear Overhauser effects

Canadian Journal of Chemistry ◽

10.1139/v83-255 ◽

1983 ◽

Vol 61 (7) ◽

pp. 1456-1464 ◽

Cited By ~ 2

Author(s):

H. Santos ◽

A. V. Xavier ◽

C.F.G.C. Geraldes

Keyword(s):

Aqueous Solution ◽

Nuclear Overhauser Effect ◽

Coupling Constants ◽

Glycosidic Bond ◽

Proton Proton ◽

Proton Coupling ◽

Vicinal Proton ◽

Group A ◽

Nuclear Overhauser ◽

Nuclear Overhauser Effects

The proton–proton and phosphorus–proton nuclear Overhauser effect (nOe) of guanosine 5′-monophosphate (5′-GMP) was measured in aqueous solution at different pH values and in the presence of excess LaIII at acid pH. These data and nOe data from the literature for other mononucleotides were used together with vicinal proton–proton coupling constants to investigate the conformations of mononucleotides in aqueous solution, especially their rotational state about the glycosidic bond. Comparison of observed and calculated enhancements using various conformational models for the glycosidic bond gave predominantly anti conformations for 5′-AMP and 5′-GMP and a mixture of syn and anti conformations for 2′-AMP, 2′-GMP, 3′-AMP, and 3′-GMP. Protonation of 5′-GMP at N-7 of the guanine base alters the amplitude of its torsion angle within the anti range. The agreement between the glycosidic nucleotide conformations defined by nOe and by the lanthanide probe method is good but not perfect. As complexation of 5′-GMP with LaIII through the phosphate group has only a small effect on the conformation of its exocyclic group, a comparison of the two methods is justified.

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The synthesis and the nuclear magnetic resonance study of β-lactam derivatives of 1,5-benzothiazepines

Canadian Journal of Chemistry ◽

10.1139/v88-047 ◽

1988 ◽

Vol 66 (2) ◽

pp. 279-282 ◽

Cited By ~ 25

Author(s):

Aron Szöllösy ◽

George Kotovych ◽

Gábor Tóth ◽

Albert Lévai

Keyword(s):

Nuclear Overhauser Effect ◽

Nuclear Magnetic Resonance Study ◽

Coupling Constants ◽

Magnetic Resonance Study ◽

Proton Proton ◽

Proton Coupling ◽

Overhauser Effect ◽

Vicinal Proton ◽

Nuclear Overhauser ◽

Derivatives Of

The synthesis and stereochemistry of seven β-lactam derivatives of 1,5-benzothiazepines are presented. The configurational and conformational analysis is based on nuclear Overhauser effect experiments, together with analysis of the vicinal proton–proton coupling constants. In the preferred conformation, the seven-membered ring is in a half-chair. Only for one compound, 2-aza-4-bromo-4-methyl-5,7-diphenyl-8-thiatricyclo[7.4.0.02,5]trideca-Δ1,9,10,12-trien-3-one, were two diastereomers isolated (compounds 6a and 6b). Six of the compounds have the 4S*, 5R*, 7R* configuration while compound 6b has the 4R*, 5R*,7R* configuration.

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Interpretation of vicinal proton-proton coupling constants by a generalized Karplus relation. Conformational analysis of the exocyclic C4′-C5′ bond in nucleosides and nucleotides: Preliminary Communication

Recueil des Travaux Chimiques des Pays-Bas ◽

10.1002/recl.19790981206 ◽

1979 ◽

Vol 98 (12) ◽

pp. 576-577 ◽

Cited By ~ 82

Author(s):

Cornelis A. G. Haasnoot ◽

Frank A. A. M. de Leeuw ◽

Harry P. M. de Leeuw ◽

Cornelis Altona

Keyword(s):

Conformational Analysis ◽

Coupling Constants ◽

Proton Proton ◽

Proton Coupling ◽

Vicinal Proton ◽

Preliminary Communication

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Studies on Prototropic Tautomerism in Neutral and Monoanionic Forms of Pyrimidines by Nuclear Magnetic Resonance Spectroscopy

Zeitschrift für Naturforschung C ◽

10.1515/znc-1977-11-1202 ◽

1977 ◽

Vol 32 (11-12) ◽

pp. 894-900 ◽

Cited By ~ 26

Author(s):

Ryszard Stolarski ◽

Mieczyslaw Remin ◽

David Shugar

Keyword(s):

Quantitative Estimation ◽

Chemical Shifts ◽

Coupling Constants ◽

Optical Methods ◽

Resonance Spectroscopy ◽

Prototropic Tautomerism ◽

Proton Proton ◽

Proton Coupling ◽

Vicinal Proton ◽

Nmr Methods

Abstract NMR methods have been applied to evaluation of prototropic tautomerism, N(1)H ⇌ N (3) H, in several selected pyrimidines, viz. the neutral forms of Isocytosine and 2-alkylthiopyrimidone-4, and the monoanionic forms of uracil, 5-fluorouracil and 4-thiouracil. The predominant tautomeric species of the neutral forms could be estimated only qualitatively from 1H chemical shifts. For the monoanionic forms this procedure was not applicable, for reasons which are discussed in detail. For the monoanionic form of uracil, 13C chemical shifts of C(5) provided a suitable criterion for quantitative estimation of the populations of the two known tautomeric species. However, the potential scope of this procedure appears somewhat limited. By contrast, the values of the vicinal proton-proton coupling constants, J (5,6), provided both necessary and adequate criteria for quantitative evaluation of the tautomer populations for all the neutral and monoanionic forms. The results were in satisfactory agreement with those obtained by optical spectroscopic methods. In some instances the results obtained in this way may be more reliable than those derived from optical methods. The range of applicability, and utility, of NMR methods to studies on protropic tautomerism in pyrimidines are critically assessed.

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Secondary structure of neutrophil-activating peptide-2 determined by 1H-nuclear magnetic resonance spectroscopy

Biochemical Journal ◽

10.1042/bj3040371 ◽

1994 ◽

Vol 304 (2) ◽

pp. 371-376 ◽

Cited By ~ 13

Author(s):

K H Mayo ◽

Y Yang ◽

T J Daly ◽

J K Barry ◽

G J La Rosa

Keyword(s):

Solution Structure ◽

Resonance Assignments ◽

Coupling Constants ◽

Resonance Spectroscopy ◽

Heparin Binding ◽

Structural Elements ◽

Solution Conformation ◽

Platelet Factor ◽

1H Nuclear Magnetic Resonance ◽

Nuclear Overhauser

Neutrophil-activating protein-2 (NAP-2) is a 72 residue protein demonstrating a range of proinflammatory activities. The solution structure of monomeric NAP-2 has been investigated by two-dimensional 1H-n.m.r. spectroscopy. Sequence-specific proton resonance assignments have been made and secondary structural elements have been identified on the basis of nuclear Overhauser data, coupling constants and amide hydrogen/deuteron exchange. The NAP-2 monomer consists of a triple-stranded anti-parallel beta-sheet arranged in a ‘Greek key’ and a C-terminal helix (residues 59-70) and is very similar to that found in the n.m.r. solution conformation of dimeric interleukin-8 and the crystal structure of tetrameric bovine platelet factor-4. Results are discussed in terms of heparin binding and neutrophil-activation properties of NAP-2.

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ChemInform Abstract: INTERPRETATION OF VICINAL PROTON-PROTON COUPLING CONSTANTS BY A GENERALIZED KARPLUS RELATION. CONFORMATIONAL ANALYSIS OF THE EXOCYCLIC C4′-C5′ BOND IN NUCLEOSIDES AND NUCLEOTIDES

Chemischer Informationsdienst ◽

10.1002/chin.198012048 ◽

1980 ◽

Vol 11 (12) ◽

Author(s):

C. A. G. HAASNOOT ◽

F. A. A. M. DE LEEUW ◽

H. P. M. DE LEEUW ◽

C. ALTONA

Keyword(s):

Conformational Analysis ◽

Abstract Interpretation ◽

Coupling Constants ◽

Proton Proton ◽

Proton Coupling ◽

Vicinal Proton

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Proton magnetic resonance study of the conformation of the pyrrolidine ring in some proline-thiohydantoins

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19882503 ◽

1988 ◽

Vol 53 (11) ◽

pp. 2503-2510 ◽

Cited By ~ 3

Author(s):

Jef J. M. Sleeckx ◽

Marc J. O. Anteunis ◽

Frans A. M. Borremans

Keyword(s):

Present Model ◽

Coupling Constants ◽

Proton Proton ◽

Proton Coupling ◽

Proton Magnetic Resonance Study ◽

Vicinal Proton ◽

Different Temperatures ◽

Experimental Justification ◽

State Assumption ◽

Methyl Phenyl

The conformational behaviour of a series of N-substituted thiohydantoins of proline was studied by proton NMR. The pseudorotational parameters of the proline moiety were calculated from the ten vicinal proton-proton coupling constants assuming a two state equilibrium (N ⇋ S). The effect of the different substituents (methyl, phenyl, para-nitrophenyl) at the thiohydantoin nitrogen on the conformation of the pyrrolidine rings is discussed. The spectra of proline-N-methylthiohydantoin were recorded at different temperatures in octadeuterotoluene solution. The conformational analysis of these spectra showed that the ratio of the populations of the N and S forms changes considerably with temperature, while the conformational identity of both the N and S forms remains strictly preserved. These facts provide an additional experimental justification of the two-state assumption, at least so for the present model compounds.

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