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Synthesis and NMR structural analysis of O-succinyl derivative of low-molecular-weight κ-carrageenan
Low-molecular-weight (LMW) κ-carrageenan was achieved through mild hydrochloric acid hydrolysis of κ-carrageenan. The acylation of LMW κ-carrageenan was performed by use of tetrabutylammonium (TBA) salt of the anionic polysaccharide fragments, succinic anhydride, 4-dimethylaminopyridine and tributylamine under homogeneous conditions in N,N-dimethylformamide at 80 °C. Investigation of FT-IR spectrum of the succinylated LMW κ-carrageenan showed that a monoester derivative with succinyl group was formed when LMW κ-carrageenan reacted with succinic anhydride. The 1H and 13C NMR spectroscopy has been used to characterize the fine structure of O-succinyl derivative of the LMW κ-carrageenan. The 13C and 1H NMR chemical shifts of disaccharide unit of O-succinyl LMW κ-carrageenan have been fully assigned using 2D NMR spectroscopic techniques. 相似文献
3.
Rondeau-Mouro C Crepeau MJ Lahaye M 《International journal of biological macromolecules》2003,31(4-5):235-244
13C and 1H NMR spectra of an ethanol insoluble material (EIM) prepared from the pericarp of mature-green (MG) and red-ripe (RR) tomato fruits were acquired in ‘liquid-like’ and cross-polarisation with dipolar decoupling and magic angle spinning (CPMAS) conditions using the same triple resonance probe. Such a strategy allowed acquisitions of various NMR experiments aimed at detecting compositional differences as well as distinguishing differences in molecular mobility for various constituent polysaccharides related with the two ripening stages. Increase of the proton dipolar decoupling power levels from 3 to 50–55 kHz during single pulse 13C acquisition, led to more intense signals for pectic and hemicellulosic polysaccharides. This behaviour was interpreted as reflecting motional restrictions of these polysaccharides inside the porous cell wall network. Measurements of the proton rotating frame relaxation times T1ρ in the ‘liquid-like’ conditions and of the proton transverse relaxation times T2 from CPMAS spectra, revealed changes in mobilities for some pectic polysaccharides in relation with ripening, particularly for the H1 and H5 protons of -1,5 arabinan (Ara) side chains of rhamnogalacturonans. These data are discussed in relation with known pectic modifications occurring during ripening and associated with the tomato fruit softening. 相似文献
4.
Synthesis and characterization of trisodium salt of bis(thiosalicylato)aurate(I): Na3[Au(TSA)2]·5H2O
K. Nomiya H. Yokoyama H. Nagano M. Oda S. Sakuma 《Journal of inorganic biochemistry》1995,60(4):289-297
Sodium salt of a water-soluble, anionic, and monomeric 1:2 complex of Au(I) with a dianion of thiosalicylic acid TSA2−(Hin2TSA) = o-HS(C6H4)COOH) was first prepared and isolated as colorless needle crystals through a stoichiometric reaction of NaAuCl4:H2TSA:NaOH = 1:4:8 molar ratio in aqueous/EtOH solution. In this reaction, TSA2− ligand has played a role of a reducing agent for the starting Au(III) ion and also of donor ligands coordinating to the reduced Au(I). This compound was characterized by complete elemental analyses, TG/DTA, FT-IR, 2D-NMR (1H-1H COSY, 1H-13C HMBC, and 1H-13C HMQC) spectroscopy, and the molmass measurement based on the cryoscopic method. It was shown that this complex was a monomeric species of Au(I) with a formula of Na3[Au(TSA)2]·5H2O in the solid state, but not a polymeric species even in aqueous solution. A full assignment of seven carbon and four proton resonances in the coordinated TSA2− ligand was achieved by the 2D 1H-13C HMBC NMR technique. 相似文献
5.
Kakiyama G Ogawa S Iida T Fujimoto Y Mushiake K Goto T Mano N Goto J Nambara T 《Chemistry and physics of lipids》2006,140(1-2):48-54
Complete 1H and 13C resonance assignments were made for a new type of 3β,7β-dihydroxy-5-cholen-24-oic acid doubly conjugated with sulfuric acid at C-3 and N-acetylglucosamine at C-7 and its glycine- and taurine-amidated triple-conjugates by the combined use of several homonuclear and heteronuclear shift-correlated 2D NMR techniques. The effects of sulfation at C-3, N-acetylglucosaminidation at C-7, and aminoacyl amidation at C-24 on the 1H and 13C chemical shifts and signal multiplicity were clarified. The shielding data serving to characterize each of the bile acid multi-conjugates are also discussed. 相似文献
6.
NMR data (1H and 13C chemical shifts, NOEs) on [[U-13C]cyclosporin A bound to cyclophilin B were compared to previously published data on the [U-13C]CsA/CyPA complex [Fesik et al., (1991) Biochemistry 30, 6574–6583]. Despite only 64% sequence identity between CyPA and CyPB, the conformation and active site environment of CsA when bound to CyPA and CyPB are nearly identical as judged by the similarity of the NMR data. 相似文献
7.
A novel route to wood modification by transesterification of vinyl esters is developed in the current study. The reaction between varied saturated and unsaturated vinyl esters and the hydroxyl groups of maritime pine sapwood (Pinus pinaster Soland) was examined using potassium carbonate as a catalyst. The esterification of wood was investigated by weight percent gain calculations (WPG), Fourier-transform infrared spectroscopy (FTIR) and 13C cross-polarization with magic-angle spinning nuclear magnetic resonance spectroscopy (13C CP–MAS NMR). Differences in the rates of modification were noted, depending on the vinyl ester used, but relatively high yields were obtained in all cases. The infrared and NMR spectra of the different esterified samples were analysed in detail and the assignment of the signals corresponding to the grafted acyl groups confirmed that esterification occurred. 相似文献
8.
The preparation of a novel mononuclear complex of zirconium having an η8-bonded pentalene ligand and two η3-allyl groups is described. Its structure has been determined by 1H and 13C NMR spectroscopy. At room temperature some of the NMR signals are broadened, revealing that the compound is structurally dynamic. It is shown that the compound has C2 symmetry with the enantiomeric forms undergoing racemisation. 相似文献
9.
Vázquez-Ramírez I Macías-Alonso M Arcos-Ramos RO Ruíz-Pérez KM Solano-Ramírez DO Iglesias Arteaga MA 《Steroids》2008,73(6):642-651
The full assignments of the 1H and 13C NMR signals of steroids bearing the 16β,23:23,26-diepoxy side chain are provided. Differentiation of the diasterotopic H-26 pair was achieved with the aid of NOESY experiments. The main substituent and steric effects associated with this moiety and their influence on the chemical shifts of the neighboring atoms are discussed. 相似文献
10.
In this paper we present a newly developed 2D selective-TOCSY-HSQC experiment for unambiguous assignment of individual sugar components of a biantennary undecasaccharide. The correlation signals between the protons and carbons of a selectively excited sugar component in the undecasaccharide were observed in a 2D selective-TOCSY-HSQC experiment. The network of proton signals of this sugar was observed in a 2D selective-TOCSY-DQFCOSY experiment. These two experiments enabled us to perform unambiguous sequential assignment of both protons and carbons of the individual sugar components in the undecasaccharide. In addition, a three-dimensional structural analysis was performed by a 2D selective-TOCSY-NOESY experiment, which clearly distinguishes between inter-sugar and intra-sugar ring NOE signals. 相似文献
11.
Maurizio Paci Carlo Federici Donatella Capitani Nicoletta Perenze Anna Laura Segre 《Carbohydrate polymers》1995,26(4):289-297
High quality antique sheets of paper have been characterized by 1H NMR relaxations and 13C CP MAS spectra. Paper can be regarded as a bicomponent material made of cellulose and water plus a small amount of organic and inorganic impurities. Semicrystalline fibrous cellulose, rich in water, is present in the I and Iβ forms. The amorphous cellulose, with a low water content, contains a higher amount of paramagnetic impurities and it is characterized by quite short 1H spin-lattice relaxations and by 113C resonances with noticeable chemical shifts. Ad hoc tailored pulse sequences are able to produce 13C CP MAS spectra in which only the amorphous content of paper is clearly observed. It is shown that water is fully bound to the cellulose lattice. It also seems reasonable to formulate the hypothesis that a larger concentration of paramagnetic ions is located in the amorphous fraction of highly degraded paper compared with paper in good condition. 相似文献
12.
In neuroblastoma × glioma hybrid cells (NG 108-15) labelled with [32P]-trisodium phosphate, [3H]-inositol and [14C]-arachidonic acid, bradykinin stimulated the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) while it had no effect on the release of [14C]-arachidonic acid (AA). The effect on PIP, was time- and dose-dependent with a maximal effect on [3H]-inositol- and [32P]-labelled cells after 10–30 s of stimulation with 10−6 M bradykinin. However, the hydrolysis of [14C]-AA labelled PIP2 was delayed compared to the effect on [3H]- and [14C]-PIP2 and was not detectable until after 60 s of stimulation. Bradykinin stimulation resulted in an increased formation of [3H]-inositol phosphates (IP) and [32P]- and [14P]- and [14C]-phosphatidic acid (PA) but the time course for PA formation did not allow the time-course for PIP2 hydrolysis. A reduced labelling of [23P]- and [14C]-phosphatidylcholine was also found in stimulated cells suggesting that PA may derive from other sources than PIP2. In conclusion, our results indicate that bradykinin activates phospholipase C, but not phospholipase A2, in NG 108-15 cells. 相似文献
13.
The structure of pullullan-like polysaccharides produced as exocellular material by different strains of Cryphonectria parasitica, the fungus responsible for chestnut tree cankers, was investigated with nuclear magnetic resonance (NMR) techniques. 13C, mono- and bidimensional 1H, and 1H–13C heteronuclear correlated NMR spectra (HSQC and HMBC) were recorded. Advanced analysis of the NMR spectra allowed the main resonance of the atoms in the maltotriose and in the maltotetraose repeat units of pullulan-like polysaccharides from C. parasitica to be recognised with confidence. In all cases investigated, the presence of large amounts of -(1→6) maltotetraose subunits was evidenced, in addition to the -(1→6) maltotriose subunits, corresponding to the repeating unit of pullulan produced by Aureobasidium pullulans and other fungi. The results were in agreement with other data from this laboratory, obtained with independent techniques. The belief that in ‘pullulans’ the maximum amount of -(1→6) maltotetraose subunits is about 7% can thus be considered as definitely outdated. 相似文献
14.
Addition of (Cp*2YH)2 (4) to 2-methyl-1,4-pentadiene produced the yttrium-alkyl-alkene chelate complex Cp*2YCH2CH2CH2C(CH3)=CH2 (2) in which a disubstituted alkene is complexed to the metal center. Evidence for coordination of the alkene unit of 2 comes from the 1H and 13C NMR chemical shifts of the vinyl units and from observation of nOe effects between Cp* protons and vinyl hydrogens. The disubstituted alkene ligand of 2 is weakly bound, and evidence for an equilibrium with substantial amounts of complex 3 with a free alkene was obtained from variable temperature 1H NMR spectroscopy. 相似文献
15.
A novel hormone conjugate has been prepared by a coupling reaction between modified estrone and dextran. In order to provide a suitable reactive estrone derivative for coupling with dextran and a spacer between the drug carrier and the hormone, the steroidal sex hormone was succinylated by reaction with succinic anhydride. Subsequently, the carboxylic acid terminal of succinylated estrone was further reacted with thionyl chloride to replace the hydroxy group with chlorine to make a better leaving group. The ester bond was employed as labile linkage between the hormone and the biopolymer carrier backbone so that the coupled estrogen could be released from the conjugate via ester hydrolysis. Structures of the modified estrone and dextran–estrone conjugate were determined by elemental analysis and by FTIR, 1H and 13C NMR spectroscopies. The degree of substitution (D.S.) per anhydroglucose (AHG) unit was 0.33 (11.0 mol-% of estrone moieties), as calculated from the 1H NMR spectrum. In vitro hydrolysis of the conjugate in aqueous phosphate buffer/ethanol solutions at pH 8.0 and 7.4 and 37°C released estrone was completed within a few days and followed zero-order kinetics. 相似文献
16.
Alemany LB 《Chemistry and physics of lipids》2002,120(1-2):33-44
Two simple experiments measuring the 13C linewidths ν1/2 and spin–lattice relaxation times T1 of each of the signals in the spectrum of trilinolein indicate that the ν1/2 and T1 values are consistent with the different degrees of motional freedom expected for the various 13C nuclei. However, for each chain, the ν1/2 and T1 measurements indicate a small reversal in mobility at C-10 relative to C-9 before motional freedom again steadily increases on each chain starting at C-11. The T1 experiment allows unambiguous assignments of the C-8 signal and C-14 signal, which differ by only 0.010 ppm. Measurements of 13C ν1/2 and T1 values on tripalmitin provide secure assignments for the C-5 and C-6 signals, for which conflicting assignments have been reported. The T1 measurements also show that among the tightly clustered C-8 through C-12 signals, the C-11 signals are the most downfield, while the C-12 signals are the most upfield, again contrary to a previous report. Similar measurements of 13C ν1/2 and T1 values on other triacylglycerols or related compounds may prove equally useful in making chemical shift assignments and detecting any discontinuities in motional freedom along a chain. The benefits and possible limitations of ultrahigh field NMR for studying triacylglycerols and related compounds are discussed. 相似文献
17.
R. Falshaw U. Hubl D. Ofman G. C. Slim M. Amjad Tariq D. K. Watt S. C. Yorke 《Carbohydrate polymers》2000,41(4):357-364
The glycosaminoglycans from the skin and head cartilage of the squid Nototodarus gouldi have been isolated and characterised by constituent disaccharide and neutral sugar analysis, 13C nuclear magnetic resonance (NMR) spectroscopy, anion exchange and size exclusion chromatography. The glycosaminoglycans from both tissues are chondroitin sulphate species. The skin consists principally of unsulphated but relatively highly glycosylated material. The chondroitin sulphate from the head cartilage is more highly sulphated, predominantly C-4,6diS (chondroitin sulphate E), with a higher molecular weight than the skin derived material but somewhat less highly glycosylated. To provide a standard for the assignment of the 13C NMR spectrum, C-4,6diS was chemically prepared from bovine tracheal chondroitin sulphate. This showed that it is not possible to distinguish between a mixture of the monosulphates, C-4S and C-6S, and the C-4,6diS by one-dimensional and simple two-dimensional 13C NMR techniques. 相似文献
18.
JoséS. Casas Eduardo E. Castellano María C. Rodríguez-Argüelles Agustín Sánchez José Sordo Julio Zukerman-Schpector 《Inorganica chimica acta》1997,260(2):4059-188
The title compoud, [TlMe2(HL)(H2O)] (HL = monoanion of pyridoxal thiosemicarbazone), crystallizers in the triclinic space group
, No. 2). The HL−anion coordinates to the thallium atom, in an unusual mode through the S atom (Tl-S = 2.832(1) Å), and also forms a weak bond with the metal atom of a neighbouring molecule to make an asymmetric bridge (Tl′…S = 3.190(1) Å). The acidic proton retained in the thiosemicarbazonato anion is located on the oxygen of the phenolic hydroxyl group. The water molecule is only 2.630(4) Å from the metal, suggesting a rather strong bond that contrasts with the long distance between the thallium and the phenolic oxygen (Tl…O(1)′ = 3.124(4) Å). If both strong and weak intermolecular interactions are taken in account, the metal has distorted octahedral coordination with the methyl groups in apical positions. The solid state IR spectrum and 1H, 13C and 205Tl NMR spectra in DMSO solution are also discussed. 相似文献
19.
R. Aquino I. Behar M. D'agostino F. De. Simone O. Schettino C. Pizza 《Biochemical Systematics and Ecology》1987,15(6):667-669
A new natural flavonol glycoside, isorhamnetin-3-rutinoside-4′-glucoside, together with rutin, narcissin, quercetin-3-(2G-glucosyl)-rutinoside and isorhamnetin-3-rutinoside-7-glucoside, was identified from the MeOH extract of Mercurialis annua L. The structures were established on the basis of chemical and spectral (1H and 13C NMR, FAB MS) data. 相似文献
20.
Oleg P. Gurjanov Nadezda N. Ibragimova Oleg I. Gnezdilov Tatyana A. Gorshkova 《Carbohydrate polymers》2008,72(4):719-729
Part of matrix polymers of flax bast fibre cell wall is tightly bound to cellulose and can not be extracted by conventional methods. To analyze these polymers, the residue, remaining after cell wall treatment with chelators and alkali, was dissolved in solution of lithium chloride in N,N-dimethylacetamide. Cellulose was precipitated by water and completely degraded by cellulase, giving the possibility to separate matrix polysaccharides, which remained in polymeric form. The obtained polymers were fractionated by gel permeation chromatography and characterized by monosaccharide analysis, staining with LM5 antibody and Yariv reagent, 1H and 13C NMR. The total yield of the polysaccharides that are tightly bound to cellulose in flax fibre, was 4.6%. The major fractions (molecular mass 100–400 kDa) were composed of galactose, accompanied by two other significant monomers, GalA and Rha, with the ratio 1.1–1.4. Composition and structure of the cellulose bound galactan permit to consider it as fragment of the high-molecular mass (2000 kDa) galactan, synthesized by the developing fibres, while forming the secondary cell wall of gelatinous type. 相似文献