scholarly journals Secondary structure of hyaluronate in solution. A 1H-n.m.r. investigation at 300 and 500 MHz in [2H6]dimethyl sulphoxide solution

1984 ◽  
Vol 220 (1) ◽  
pp. 197-205 ◽  
Author(s):  
J E Scott ◽  
F Heatley ◽  
W E Hull
Keyword(s):  
Secondary Structure ◽  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Glucuronic Acid ◽  
Chondroitin Sulphate ◽  
Chemical Shifts ◽  
Heparan Sulphate ◽  
Carbonyl Oxygen ◽  
Dimethyl Sulphoxide ◽  
Coupling Constants

The 1H-n.m.r. spectra of solutions in [2H6]dimethyl sulphoxide of the sodium salts of tetra-, hexa- and octa-saccharides prepared from hyaluronate by testicular-hyaluronidase digestion were examined at 300 and 500 MHz. The signals from hydroxy groups at positions 2 and 3 in the glucuronic acid moiety were assigned. Their chemical shifts and associated temperature-dependencies, as well as their coupling constants, depended on whether or not the uronic acid was at the non-reducing end. Deviations from the ‘normal’ pattern of hydroxy-group proton n.m.r. behaviour were attributable to participation in hydrogen bonds, either to the acetamido carbonyl oxygen atom or the pyranose ring oxygen atom of neighbouring N-acetylhexosamine moieties. A secondary structure, containing four different hydrogen bonds per trisaccharide unit of glucuronsyl-hexosaminyl-glucuronic acid, was demonstrated. This is the first complete and detailed secondary structure to be established for hyaluronate in any solvent. Hyaluronate is compared with chondroitin sulphate, dermatan sulphate, heparan sulphate and keratan sulphate in their potential to form secondary structures with features in common. The significance of the details of the structure to its overall stability, and the probability of their persistence into aqueous environments, are discussed. The presence of all or most of the secondary structure in glycosaminoglycuronans is correlated with a space-filling function in the tissue, and with a high carbohydrate content in the parent proteoglycan in the case of the chondroitin sulphates.

scholarly journals Detection of secondary structure in glycosaminoglycans via the1H n.m.r. signal of the acetamido NH group

1982 ◽  
Vol 207 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J E Scott ◽  
F Heatley
Keyword(s):  
Secondary Structure ◽  
Chondroitin Sulphate ◽  
Heparan Sulphate ◽  
Periodate Oxidation ◽  
Close Approach ◽  
Dimethyl Sulphoxide ◽  
Space Filling ◽  
Keratan Sulphate ◽  
Inorganic Cations ◽  
Acid Glycosaminoglycans

Two simple methods for dissolving salts of acid glycosaminoglycans with inorganic cations (e.g. Li+ and Na+) in dry dimethyl sulphoxide are described. Complete n.m.r. spectra of, e.g., Na+ and Li+ salts of chondroitin sulphate and keratan sulphate were obtained on these solutions. In [2H6]dimethyl sulphoxide the NH resonance of 2-acetamido-2-deoxy hexosides is in the range 7.2-8.0 delta, but is downfield (8.3-9.3 delta) when the NH is H-bonded to -CO2-. Heparan sulphate shows two NH resonances, of which one (at 8.3 delta) is probably indicative of H-bonding. Space-filling models show that a very close approach of NH to -CO2- across the alpha-glucosaminidic bond is possible, and a solution configuration for heparan sulphate is proposed. The n.m.r. results are entirely compatible with interpretations of periodate-oxidation kinetics, based on H-bonded secondary structures present in hyaluronate and chondroitin sulphates, but not in dermatan (or keratan) sulphate.

scholarly journals Stabilization of N-, N,N-, N,N′-methylated and unsubstituted simple amidine salts by multifurcated hydrogen bonds

2006 ◽  
Vol 20 (4) ◽  
pp. 169-176 ◽  
Author(s):  
Jarosław Spychała
Keyword(s):  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Chemical Shifts ◽  
2D Nmr ◽  
Biological Properties ◽  
Carbonyl Oxygen ◽  
Relative Strength ◽  
Intramolecular Interactions ◽  
Covalent Bonds ◽  
Natural Isotopic Abundance

In the light of the usefulness of amidines in medicinal chemistry, this paper considers the effects on biological properties and chemical reactivities of organic molecules affected by intramolecular interactions. The study of chemical shifts has been an important source of information on the electronic structure of amidine salts and their ability to form non-covalent bonds with nucleic acids. The NMR and IR results demonstrate that hydrogen bonds are a force for promoting chemical reactions. The thymine O2 carbonyl oxygen in a close proximity to the amidinium cation does interact with the appropriately spaced amidinium NH donor moieties. The1H-15N 2D NMR (GHSQC and GHMBC) spectra with natural isotopic abundance of15N fully confirm the intramolecular character of the bonds. A rule able to estimate the relative strength of the new multifurcated hydrogen bonds is given. The appearance of the ΔδNHchemical shift differences near zero is due to the strong intramolecular interactions. The strength of the H-bond donation by acetamidines is reflected in the N–H dissociation/recombination process (positive charge shift has been invoked to explain other effects on benzamidines). The temperature dependence of chemical shift for the amidine NH protons in dimethyl sulfoxide solutions is herein discussed.

scholarly journals Secondary Structure of Chondroitin Sulphate in Dimethyl Sulphoxide

1983 ◽  
Vol 130 (3) ◽  
pp. 491-495 ◽  
Author(s):  
John E. SCOTT ◽  
Frank HEATLEY ◽  
Malcolm N. JONES ◽  
Allan WILKINSON ◽  
Anthony H. OLAVESEN
Keyword(s):  
Secondary Structure ◽  
Chondroitin Sulphate ◽  
Dimethyl Sulphoxide

scholarly journals Synthesis of glycosaminoglycans by human embryonic lung fibroblasts. Different distribution of heparan sulphate, chondroitin sulphate and dermatan sulphate in various fractions of the cell culture

1977 ◽  
Vol 167 (2) ◽  
pp. 383-392 ◽  
Author(s):  
Ingrid Sjöberg ◽  
Lars-Åke Fransson
Keyword(s):  
Glucuronic Acid ◽  
Chondroitin Sulphate ◽  
Heparan Sulphate ◽  
Periodate Oxidation ◽  
Exchange Chromatography ◽  
Lung Fibroblasts ◽  
Relative Distribution ◽  
Dermatan Sulphate ◽  
Human Embryonic Lung ◽  
Iduronic Acid

Foetal human lung fibroblasts, grown in monolayer, were allowed to incorporate 35SO42− for various periods of time. 35S-labelled macromolecular anionic products were isolated from the medium, a trypsin digest of the cells in monolayer and the cell residue. The various radioactive polysaccharides were identified as heparan sulphate and a galactosaminoglycan population (chondroitin sulphate and dermatan sulphate) by ion-exchange chromatography and by differential degradations with HNO2 and chondroitinase ABC. Most of the heparan sulphate was found in the trypsin digest, whereas the galactosaminoglycan components were largely confined to the medium. Electrophoretic studies on the various 35S-labelled galactosaminoglycans suggested the presence of a separate chondroitin sulphate component (i.e. a glucuronic acid-rich galactosaminoglycan). The 35S-labelled galactosaminoglycans were subjected to periodate oxidation of l-iduronic acid residues followed by scission in alkali. A periodate-resistant polymer fraction was obtained, which could be degraded to disaccharides by chondroitinase AC. However, most of the 35S-labelled galactosaminoglycans were extensively degraded by periodate oxidation–alkaline elimination. The oligosaccharides obtained were essentially resistant to chondroitinase AC, indicating that the iduronic acid-rich galactosaminoglycans (i.e. dermatan sulphate) were composed largely of repeating units containing sulphated or non-sulphated l-iduronic acid residues. The l-iduronic acid residues present in dermatan sulphate derived from the medium and the trypsin digest contained twice as much ester sulphate as did material associated with the cells. The content of d-glucuronic acid was low and similar in all three fractions. The relative distribution of glycosaminoglycans among the various fractions obtained from cultured lung fibroblasts was distinctly different from that of skin fibroblasts [Malmström, Carlstedt, Åberg & Fransson (1975) Biochem. J.151, 477–489]. Moreover, subtle differences in co-polymeric structure of dermatan sulphate isolated from the two cell types could be detected.

scholarly journals Orthogonal halogen and hydrogen bonds involving a peptide bond model

CrystEngComm ◽  
2014 ◽  
Vol 16 (35) ◽  
pp. 8102-8105 ◽  
Author(s):  
Vera Vasylyeva ◽  
Susanta K. Nayak ◽  
Giancarlo Terraneo ◽  
Gabriella Cavallo ◽  
Pierangelo Metrangolo ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Peptide Bond ◽  
Carbonyl Oxygen ◽  
Carbonyl Oxygen Atom ◽  
Halogen Bonds ◽  
Bond Model

N-Methylacetamide, a well-known peptide bond model, and dihalotetrafluorobenzenes form co-crystals and show geometrically orthogonal hydrogen and halogen bonds sharing the same carbonyl oxygen atom.

scholarly journals Molecular conformation of sodium heparan sulphate in the condensed phase

1977 ◽  
Vol 161 (3) ◽  
pp. 495-498 ◽  
Author(s):  
H F Elloway ◽  
E D T Atkins
Keyword(s):  
Hydrogen Bonds ◽  
Condensed Phase ◽  
Molecular Conformation ◽  
Glucuronic Acid ◽  
Heparan Sulphate ◽  
Helical Conformation ◽  
Molecular Models ◽  
X Ray Diffraction ◽  
X Ray

By using the X-ray-diffraction results reported previously for sodium heparan sulphate, a twofold helical conformation with an axially projected disaccharide repeat (h) equal to 0.93 nm has been examined in detail. On the basis of a repeating sequence of 1,4-alpha-D-glucosamine and 1,4-beta-D-glucuronic acid, trial and stereochemically feasible molecular models were computer-generated. An optimum twofold helical conformation is proposed, incorporating stabilizing intra-chain hydrogen bonds across both glycosidic linkages.

Carbon-13 nmr shifts and C—H coupling constants of deoxybenzoins and related acetophenones

1981 ◽  
Vol 59 (15) ◽  
pp. 2266-2282 ◽  
Author(s):  
Hem Chandra Jha ◽  
Fritz Zilliken ◽  
Werner Offermann ◽  
Eberhard Breitmaier
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Carbonyl Oxygen ◽  
Coupling Constants ◽  
Structural Variations ◽  
Naturally Occurring ◽  
Internal Hydrogen ◽  
Benzene Rings ◽  
Substitutional Saturation

13C Chemical shifts and resolved carbon–proton couplings of 39 deoxybenzoins and 11 acetophenones, most of which have naturally occurring substitution patterns, are assigned. Individual benzene rings turned out to have typical parameters not affected by structural variations in the rest of the molecule. Due to substitutional saturation, however, these benzenoid carbon shifts markedly deviate from increment additivity. A few trends of these deviations are described. Phenolic hydrogens, fixed between hydroxyl and carbonyl oxygen due to internal hydrogen bonding, are shown to give rise to additional carbon-splittings.

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