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1.
From a brain extract of the catadromous fish, striped mullet (Mugil cephalus), two visceral excitatory neuropeptides (Mvp-1 and Mvp-2) were isolated by means of reversed phase chromatography together with bioassay on fish hindgut. The primary structure of Mvp-1 was elucidated to be SGPAGVLamide by ESI-Q-TOF mass spectrometry. The threshold concentration of Mvp-1 that changes spontaneous contraction of mullet hindgut was between 10(-9) and 10(-8) M. In addition, Mvp-1 was found to exert excitatory activities on some other smooth muscle segments (oviduct and esophagus) of mullet but it did not show any effect on body wall muscle strips. Therefore, the present study suggests that Mvp-1 and Mvp-2 peptides act as factors that control visceral contractions of mullet gastrointestinal tract. 相似文献
2.
Isofloridosides (1-O-alpha-D-galactopyranosylglycerol) and floridoside (2-O-alpha-D-galactopyranosylglycerol) were extracted from the red alga Porphyra umbilicalis (Linné) Kützing (Bangiales, Rhodophyta). Their separation was achieved by HPLC (NH(2) P50 column) after successive purification of the crude extract by ion-exchange chromatography and HPLC (Sugar-Pak TM1 column). 1D and 2D NMR spectroscopy experiments allowed to completely assign the (1)H and (13)C spectra of D-isofloridoside. 相似文献
3.
High resolution NMR for studying lipid hydrolysis and esterification in cod (Gadus morhua) gonads 总被引:2,自引:0,他引:2
High resolution NMR was applied to study biochemical changes of lipids in cod (Gadus morhua) gonads during 7 days storage at 4 degrees C. Changes were observed in the (13)C and (1)H resonances of cholesterol which were due to esterification of fatty acids at the hydroxyl position in roe and milt. Furthermore, the (13)C NMR spectra showed that the lipolytic changes in milt and roe where different. New resonances appeared during storage, due to formation of specific free fatty acids, with the corresponding changes in resonances of the esterified carbonyls and glycerols. The highly unsaturated n-3 fatty acids were hydrolysed from the sn-1 and sn-2 position of both phosphatidylcholine and phosphatidylethanolamine in milt. The lipolytical changes in roe were less prominent compared to the changes in milt, however significant levels of sn-1-lysophospholipids was detected both in roe and milt. The current data demonstrate that high resolution NMR may be a suitable method to non-destructively study hydrolysis and esterification reactions occurring in heterogeneous marine lipids in a one step procedure. 相似文献
4.
Corsaro MM De Castro C Naldi T Parrilli M Tomás JM Regué M 《Carbohydrate research》2005,340(13):2212-2217
The complete (1)H and (13)C NMR characterization of the tetrasaccharide repeating unit from the K2 polysaccharide of Klebsiella pneumoniae strain 52145 is reported. [chemical structure] In addition a model for its secondary structure was suggested on the basis of dynamic and molecular calculations. 相似文献
5.
The chemical structure and interactions of the cell wall polysaccharides from the red edible seaweed Palmaria palmata were studied by liquid-like magic-angle-spinning (MAS) and cross-polarization MAS (CPMAS) solid-state 13C NMR spectroscopy. The liquid-like MAS and CPMAS 13C NMR spectra of the rehydrated algal powder revealed the presence of beta-(1-->4)/beta-(1-->3)-linked D-xylan with chemical shifts close to those observed in the solution 13C NMR spectrum of the polysaccharide. Observation of mix-linked xylan in the liquid-like MAS 13C NMR spectrum indicated that part of this cell wall polysaccharide is loosely held in the alga. The CPMAS NMR spectrum of the dry algal powder alcohol insoluble residue (AIR) showed broad peaks most of which corresponded to the mix-linked xylan. Hydration of AIR induced a marked increase in the signal resolution also in the CPMAS NMR spectra together with a shift of the C-3 and C-4 signals of the (1-->3)- and (1-->4)-linked xylose, respectively. Such modifications were present in the spectrum of hydrated (1-->3)-linked xylan from the green seaweed Caulerpa taxifolia and absent in that of (1-->4)-linked xylan from P. palmata. This result emphasizes the important role of (1-->3) linkages on the mix-linked xylan hydration-induced conformational rearrangement. The mix-linked xylan signals were observed in the CPMAS NMR spectrum of hydrated residues obtained after extensive extractions by NaOH or strong chaotropic solutions indicating strong hydrogen bonds or covalent linkages. T(1 rho) relaxations were measured close or above 10 ms for the mix-linked xylan in the dry and hydrated state in AIR and indicated that the overall xylan chains likely remain rigid. Rehydration of the mix-linked xylan lead to a decrease in the motion of protons bounded to the C-1 and C-4 carbons of the (1-->4)-linked xylose supporting the re-organization of the xylan chains under hydration involving junction-zones held by hydrogen bonds between adjacent (1-->4)-linked xylose blocks. The CPMAS NMR spectrum of both dry and rehydrated residues obtained after NaOH and HCl extractions demonstrated the presence of cellulose and (1-->4)-linked xylans. The structures of the different polysaccharides are discussed in relation to their interactions and putative functions on the cell wall mechanical properties in P. palmata. 相似文献
6.
Summary Heteronuclear 2D (13C, 1H) and (15N, 1H) correlation spectra of (13C, 15N) fully enriched proteins can be acquired simultaneously with virtually no sensitivity loss or increase in artefact levels. Three pulse sequences are described, for 2D time-shared or TS-HSQC, 2D TS-HMQC and 2D TS-HSMQC spectra, respectively. Independent spectral widths can be sampled for both heteronuclei. The sequences can be greatly improved by combining them with field-gradient methods. By applying the sequences to 3D and 4D NMR spectroscopy, considerable time savings can be obtained. The method is demonstrated for the 18 kDa HU protein.Abbreviations HMQC
heteronuclear multiple-quantum coherence spectroscopy
- HSQC
heteronuclear single-quantum coherence spectroscopy
- HSMQC
heteronuclear single- and multiple-quantum coherence spectroscopy
- NOESY
nuclear Overhauser enhancement spectroscopy 相似文献
7.
The present study was performed to trace the decisive evidence for mixed infection of 2 Myxobolus species, M. episquamalis and Myxobolus sp., in the gray mullet, Mugil cephalus, from Korean waters. Mullets with whitish cyst-like plasmodia on their scales were collected near a sewage plant in Yeosu, southern part of Korea, in 2009. The cysts were mainly located on scales and also found in the intestine. The spores from scales were oval in a frontal view, tapering anteriorly to a blunt apex, and measured 7.2 µm (5.8-8.0) in length and 5.3 µm (4.7-6.1) in width. Two polar capsules were pyriform and extended over the anterior half of the spore, measuring 3.5 µm (2.3-4.8) in length and 2.0 µm (1.5-2.2) in width. In contrast, the spores from the intestine were ellipsoidal, 10.4 µm (9.0-11.9) in length and 8.4 µm (7.3-10.1) in width. The polar capsules were pyriform but did not extend over the anterior half of the spore, 3.7 µm (2.5-4.5) in length and 2.2 µm (1.8-2.9) in width. The nucleotide sequences of the 18S rDNA gene of the 2 myxosporean spores from scales and intestine showed 88.1% identity to each other and 100% identity with M. episquamalis and 94.5% identity with M. spinacurvatura from mullet, respectively. By the above findings, it is first confirmed that mullets from the Korean water are infected with 2 myxosporean species, M. episquamalis and Myxobolus sp. 相似文献
8.
The hydroxyl group stereochemistry of complexation of sodium vanadate(V) with Me alpha-Manp, Me alpha- and beta-Galp and selected O-methyl derivatives in D(2)O was determined by 51V, 1D and 2D 13C NMR spectroscopy at pD 7.8. The 51V approach served to show the extent of complexation and the minimum number of esters formed. That of Me alpha-Manp gave rise mainly to a 51V signal at delta -515, identical with that of its 4,6-di-O-methyl derivative, which had only a 2,3-cis-diol exposed. The 13C NMR spectra contained much weaker signals of the complexes, but both glycosides showed strong C-2 and C-3 alpha-shifts of +17.3 and +10.8 ppm, respectively. As expected, Me 2,3-Me(2)-alpha-Manp, which contains a 4,6-diol, did not complex. Me Galp anomers and their derivatives showed more diversity in the structure of its oxyvanadium derivatives. Me alpha-Galp, with its 3,4-cis-diol, complexed to give rise to 51V signals at delta -495 (9%), -508 (10%), and -534 (4%). These shifts and proportions were maintained with Me beta-Galp and Me 6Me-alpha-Galp. 51V NMR spectroscopy showed that Me 3Me-beta-Galp, with its possibly available 4,6-diol, did not complex. Similarly, Me alpha-Galp+vanadate gave a 13C DEPT spectrum that did not contain an inverted signal at delta >71.4, as would be expected of a C-6 resonance suffering a strong downfield alpha-shift. Me 2,6-Me(2)-alpha-Galp, with a 3,4-cis-diol group, gave rise to two 51V signals of complexes at delta -492 (9%) and -508 (9%), showing more than one structure of oxyvanadium derivatives. 相似文献
9.
Cyclosophoraoses (cyclic-(1-->2)-beta-D-glucans) produced by Rhizobium meliloti were used as a novel chiral NMR solvating agent. 13C NMR spectroscopic analysis as an enantiodiscriminating tool was carried out where NMR signal splittings were observed on the interactions of cyclosophoraoses with the enantiomers of N-acetylphenylalanine, catechin and propranolol. The 13C chemical shifts of cyclosophoraoses induced by the enantiomeric interactions predominantly occurred at the C-1 and C-2 carbons associated with the -glycosidic linkage. 相似文献
10.
The X-ray diffraction analysis, (13)C CP MAS NMR spectra and powder X-ray diffraction patterns were obtained for selected methyl glycosides: alpha- and beta-d-lyxopyranosides (1, 2), alpha- and beta-l-arabinopyranosides (3, 4), alpha- and beta-d-xylopyranosides (5, 6) and beta-d-ribopyranoside (7) and the results were confirmed by GIAO DFT calculations of shielding constants. In X-ray diffraction analysis of 1 and 2, a characteristic shortening and lengthening of selected bonds was observed in molecules of 1 due to anomeric effect and, in crystal lattice of 1 and 2, hydrogen bonds of different patterns were present. Also, an additional intramolecular hydrogen bond with the participation of ring oxygen atom was observed in 1. The observed differences in chemical shifts between solid state and solution come from conformational effects and formation of various intermolecular hydrogen bonds. The changes in chemical shifts originating from intermolecular hydrogen bonds were smaller in magnitude than conformational effects. Furthermore, the powder X-ray diffraction (PXRD) performed for 4, 5 and 7 revealed that 7 existed as a mixture of two polymorphs, and one of them probably consisted of two non-equivalent molecules. 相似文献
11.
The kavalactone, 11-methoxy-5,6-dihydroyangonin, and eight previously reported analogs along with four other aromatic compounds were isolated from the root extracts of Piper methysticum (Kava Kava). Their structural elucidations were made by 1H and 13C NMR spectroscopic assignments using COSY, HMBC and HMQC experiments. 相似文献
12.
An inclusion complex between imazalil (IMZ), a selected fungicide, and cyclomaltoheptaose (beta-cyclodextrin, betaCD) was obtained using supercritical fluid carbon dioxide. The best preparation conditions were determined, and the inclusion complex was investigated by means of 1H NMR spectroscopy in aqueous solution and 13C CPMAS NMR spectroscopy in the solid state. Information on the geometry of the betaCD/IMZ complex was obtained from ROESY spectroscopy, while the dynamics of the inclusion complex in the kilohertz range was obtained from the proton spin-lattice relaxation times in the rotating frame, T(1rho) (1H). 相似文献
13.
Sassaki GL Gorin PA Reis RA Serrato RV Elífio SL Iacomini M 《Carbohydrate research》2005,340(11):1808-1817
The photobiont of the lichen, Dictyonema glabratum (Scytonema sp.), was isolated and cultivated in a soil-extract medium and submitted to chemical analysis. Successive extractions with CHCl3-MeOH, aqueous MeOH, and H2O gave rise to solutions of lipids (25%), low-molecular-weight carbohydrates (22%), and polysaccharides (4%), respectively. TLC of the lipid extract showed the presence of glycolipids, which were further purified and examined by NMR spectroscopy and GC-MS. Monogalactosyldiacylglycerol (1%), digalactosyldiacylglycerol (0.8%), trigalactosyldiacylglycerol (0.4%), and sulfoquinovosyldiacylglycerol (0.5%) were identified. The most abundant fatty acid ester in each fraction was palmitic (C16:0), but a great variation of the ester composition from one to another was found. Others present were those of C12:0, C14:0, C15:0, C16:1, C17:0, C18:0, C18:1, C18:2, C18:3, C22:0, C22:2, and C24:0. The lipid extract was also subjected to acid methanolysis, which gave rise to dodecane, 2-Me-heptadecane, 2,6-Me2-octadecane, and 8-Me-octadecane, methyl esters of C14:0, C15:0, C16:0, C16:1, C17:0, C18:0, C18:1, C18:2, C20:0, and C24:0 fatty acids, and the dimethyl ester of decanedioic acid. The polysaccharide had mainly Glc, Gal, and Man, with small amounts of 3-O-methylrhamnose and 2-O-methylxylose, both found in plants, and unexpectedly, some of the units were beta-galactofuranose, typical of fungal, but not cyanobacterial polysaccharides. The low-molecular-weight carbohydrates showed mannose as the main free reducing sugar, which differs from Nostoc sp. and Trebouxia sp. photobionts. 相似文献
14.
In vivo administration experiments using stable (13C) and radio (14C) labeled precursors established that the optically active 8-2' linked lignans, (-)-cis-blechnic, (-)-trans-blechnic and (-)-trans-brainic acids, were directly derived from L-phenylalanine, cinnamate, and p-coumarate but not either from tyrosine or acetate. The radiochemical time course data suggest that the initial coupling product is (-)-cis-blechnic acid, which is then apparently converted into both (-)-trans-blechnic and (-)-trans-brainic acids in vivo. These findings provide additional evidence for vascular plant proteins engendering distinct but specific phenolic radical-radical coupling modes, i.e., for full control over phenylpropanoid coupling in vivo, whether stereoselective or regiospecific. 相似文献
15.
Multi-component analysis of marine lipids in fish gonads with emphasis on phospholipids using high resolution NMR spectroscopy 总被引:2,自引:0,他引:2
High resolution NMR has been applied for assessment of lipid classes and acyl stereospecific positions of fatty acids in marine phospholipids and triacylglycerols. 1D and 2D NMR techniques in combination with recording of a number of reference standards have been used to interpret the (1)H and (13)C NMR spectra of fish gonads. (13)C NMR spectra gave information regarding the polyunsaturated fatty acids (PUFAs) in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The carbonyl resonances showed that n-3 PUFAs primarily were esterified in the sn-2 position of PC and PE. The glycerol resonances showed that the PC/PE ratio was higher in roe than in milt and that roe comprised more triacylglycerols than milt. Thin layer chromatography showed that milt contained 2.4 times more cholesterol than roe, which was also found by integrating the (1)H NMR spectra. Concentration (mol%) of n-3 fatty acids were calculated from the (1)H NMR data and showed 44.8 and 36.3% in roe and milt, respectively. 相似文献
16.
Digeneaside (alpha-D-mannopyranosyl-(1-->2)-D-glycerate) was extracted from the red algae, Bostrychia binderii, and purified by adsorption and gel-filtration chromatography. HPLC and ESI-MS techniques were used to follow purification steps and characterize digeneaside. NMR spectroscopy experiments (1D 1H, 13C, DEPT and 2D HMQC, COSY and TOCSY) were used to fully assign the 1H and 13C spectra. 相似文献
17.
Saitô H 《Chemistry and physics of lipids》2004,132(1):101-112
We have compared site-directed 13C solid-state NMR spectra of [3-13C]Ala- and/or [1-13C]Val-labeled membrane proteins, including bacteriorhodopsin (bR), pharaonis phoborhodopin (ppR), its cognate transducer (pHtrII) and Escherichia coli diacylglycerol kinase (DGK), in two-dimensional (2D) crystal, lipid bilayers, and detergent. Restricted fluctuation motions of these membrane proteins due to oligomerization of bR by specific protein-protein interactions in the 2D crystalline lattice or protein complex between ppR and pHtrII provide the most favorable environment to yield well-resolved, fully visible 13C NMR signals for [3-13C]Ala-labeled proteins. In contrast, several signals from such membrane proteins were broadened or lost owing to interference of inherent fluctuation frequencies (10(4)-10(5)Hz) with frequency of either proton decoupling or magic angle spinning, if their 13C NMR spectra were recorded as a monomer in lipid bilayers at ambient temperature. The presence of such protein dynamics is essential for the respective proteins to achieve their own biological functions. Finally, spectral broadening found for bR and DGK in detergents were discussed. 相似文献
18.
Eight oligosaccharide subunits, generated by endoglucanase treatment of the plant polysaccharide xyloglucan isolated from the culture filtrate of suspension-cultured tomato (Lycopersicon esculentum) cells, were structurally characterized by NMR spectroscopy. These oligosaccharides, which contain up to three endogenous O-acetyl substituents, consist of a cellotetraose core with alpha-D-Xylp residues at O-6 of the two beta-D-Glcp residues at the non-reducing end of the core. Some of the alpha-D-Xylp residues themselves bear either an alpha-L-Arap or a beta-D-Galp residue at O-2. O-Acetyl substituents are located at O-6 of the unbranched (internal) beta-D-Glcp residue, O-6 of the terminal beta-D-Galp residue, and/or at O-5 of the terminal alpha-L-Arap residue. Structural assignments were facilitated by long-range scalar coupling interactions observed in the high-resolution gCOSY spectra of the oligosaccharides. The presence of five-bond scalar coupling constants in the gCOSY spectra provides a direct method of assigning O-acetylation sites, which may prove generally useful in the analysis of O-acylated glycans. Spectral assignment of these endogenously O-acetylated oligosaccharides makes it possible to deduce correlations between their structural features and the chemical shifts of diagnostic resonances in their NMR spectra. 相似文献
19.
The (13)C NMR spectra of methyl beta-d-glucopyranoside, methyl beta-d-galactopyranoside, methyl beta-d-xylopyranoside, and methyl beta-l-arabinopyranoside were recorded in CaCl(2)/KCl+D(2)O mixtures and in D(2)O. The chemical shifts of C-1, C-3, and C-5 in the methyl beta-d-glucopyranoside and methyl beta-d-galactopyranoside decrease rapidly as molalities of CaCl(2)/KCl increase, while those of C-1, C-2, and C-3 in the methyl beta-d-xylopyranoside and methyl beta-l-arabinopyranoside decrease rapidly as molalities of CaCl(2)/KCl increase. Cations (Ca(2+)/K(+)) can weakly complex with O in OMe of the pyranosides studied. Results are discussed in terms of the stereochemistry of the pyranoside molecules and the structural properties of the ions. 相似文献
20.
Compound-specific hydrogen and carbon isotopic compositions in n-alkanoic acids, phytol and sterols were determined for various plant classes (terrestrial C3-angiosperm; C3-gymnosperm; C4; crassulacean acid metabolism (CAM); and aquatic C3 plants) in order to investigate isotopic fractionations among various plant classes. In all plants, lipid biomolecules are depleted in both D (up to 324 per thousand ) and 13C (up to 14.7 per thousand ) relative to ambient water and bulk tissue, respectively. In addition, the magnitude of D- and 13C-depletion of lipid biomolecules is distinctive depending on plant classes. For example, C3 angiosperm n-alkanoic acids are less depleted in D (95+/-23 per thousand ) and 13C (4.3 +/- 2.5 per thousand ) relative to ambient water and bulk tissue, respectively, while C4 plant n-alkanoic acids are more depleted in D (119 +/- 15 per thousand ) and 13C (10.2 +/- 2.0 per thousand ). On the other hand, C3 angiosperm phytol and sterols are much more depleted in D (306 +/-12 per thousand for phytol, 211+/-15 per thousand for sterol) with less depletion in 13C (4.1 +/- 1.1 per thousand for phytol, 1.3 +/- 0.9 per thousand for sterol) relative to ambient water and bulk tissue, respectively, while C4 plant phytol and sterols are less depleted in D (254 +/- 7 per thousand for phytol, 186 +/- 13 per thousand for sterols) with much more depletion in 13C (9.0 +/- 1.2 per thousand for phytol, 5.0 +/- 1.1 per thousand for sterols). Among various plant classes, there is a positive correlation between the D- and 13C-depletion for n-alkanoic acids, while a negative correlation was found for phytol and sterols from the same plants. 相似文献