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A synthesis of 5-thio-D-galactose, in the form of its crystalline, anomeric methyl glycopyranosides, is described. Compounds prepared as intermediates included ethyl 2,3-di-O-(tert-butyldimethylsilyl)-5,6-O-carbonyl-β-D-galactofuranoside, the corresponding 5,6-dideoxy-5,6-epithio derivative, and ethyl 2,3,6-tri-O-acetyl-5-S-acetyl-5-thio-β-D-galactofuranoside. On methanolysis, the latter afforded methyl 5-thio-α-D-galactopyranoside which, in turn, was transformed into methyl 5-thio-β-D-galactopyranoside. Acetolysis proved to be less satisfactory for incorporation of the sulfur atom into a pyranose ring-form. Characteristics of the 13C-n.m.r. spectra of derivatives of 5-thio-D-galactose are described, including the fact that 1JC,H values for the anomeric pyranosides differ by only 1–3 Hz, as compared with ≈ 10 Hz for their oxygen analogs. 相似文献
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Stereocontrolled synthesis of 1-O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-2,3-O-isopropylidene-D-glycerol (6) was achieved in good yield by use of the modified, orthoester method. Compound 6 was then transformed into 1-deoxy-3-O-phosphono-D-glycerol-1-yl β-D-glucopyranoside (1), identical with the repeating unit of the teichoic acid isolated from the cell wall of Bacillus subtilis var. niger WM, in a regio-controlled way, unambiguous evidence for the assignment of the stereochemistry of the natural product being provided by the 13C-n.m.r. data for 1 and its L-glycerol-1-yl isomer. 相似文献
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G.l.c.-mass spectrometry has been used to characterize the products of N-deacetylation-nitrous acid deamination of per-O-methylated derivatives (8–11) of methyl 2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-α-D-glucopyranoside(1), methyl (2) and benzyl (3) 2-acetamido-2-deoxy-4-O-β-D-galactopyranosyl-β-D-glucopyranosides, and methyl 2-acetamido-2-deoxy-6-O-β-D-galactopyranosyl-α-D-glucopyranoside (4). 2,5-Anhydrohexoses have been converted into alditol trideuteriomethyl ethers, alditol acetates, and aldononitriles. The importance of side reactions that lead to the formation of 2-deoxy-2-C-formylpentofuranosides is discussed. 相似文献
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Birger Thorsteinsson Jørgen Gliemann Jørgen Vinten 《Biochimica et Biophysica Acta (BBA)/General Subjects》1976,428(1):223-227
The distribution spaces at equilibrium for 3H2O, [14C]urea and were measured in white fat cells using centrifugation through silicone oil at 2500 × g; no significant differences were observed. l-[14C] Glucose added immediately before the centrifugation was used as a marker for the extracellular water space. The calculated intracellular water content of the cells after the centrifugation through oil (e.g. 3H2O space minus l-[14C] glucose space) is an unbiased measure of the water content of the cells in suspension as judged by the following criteria: (1) The intracellular distribution space for methylglucose at equilibrium (methylglucose space minus l-glucose space) was not different from that calculated from a methylglucose wash-out curve. (2) The intracellular content of l-[14C]glucose (half time of efflux about 60 min) in cells preloaded during incubation of the tissue with collagenase was not different in cells recovered by (a) centrifugation through oil at 2500 × g, (b) centrifugation through oil at 600 × g, (c) centrifugation at 600 × g in the absence of oil and (d) filtration on Millipore filters.The intracellular content of water determined on cells from single rats weighing 120–150 g was 2.75 ± 0.55 μl/100 μl fat cells (± S.D., n = 30). The intracellular content of potassium, determined on cells from the same rats, was 252 ± 62 nmols/100 μl fat cells (± S.D., n = 30). The concentration of potassium in the intracellular water was calculated as 104 ± 15 mM (± S.D., n = 30). 相似文献
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The evolution of H2 gas in an illuminated chloroplast plus hydrogenase system was shown to function for six and a half hours at a continuous rate of about 10 μmoles H2/mg. chlorophyll/hour. Chloroplasts from various plant species, using different isolation media, and storage in a fixed state (glutaraldehyde) at 4°, ?5° and ?196° were shown to catalyze H2 production. Both and hydrogenase were used. From the use of the photosystem II inhibitors DCMU and DBMIB and heat inactivation of photosystem II, it was concluded that H2O was the source of electrons for H2 gas production. 相似文献
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S Toma G Coppa P V Donnelly R Ricci N Di Ferrante S K Srivastava 《Carbohydrate research》1981,96(2):271-290
The disaccharide 2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1 goes to 3)-D-[1-3H]-galactitol, prepared from keratan sulfate, was rapidly hydrolyzed by the A and B isoenzymes of normal human liver hexosaminidase (EC 3.2.1.30), and by the B isoenzyme prepared from the liver of a patient who had died of Tay-Sachs disease. The disaccharide substrate was also hydrolyzed by extracts of normal, cultured-skin fibroblasts, and fibroblasts of patients with Tay-Sachs disease, whereas it was not hydrolyzed by fibroblast extracts of patients with Sandhoff disease. Thus, effective degradation of keratan sulfate, secondary to a defect of the beta subunits present in the A and B isoenzymes of hexosaminidase, may contribute to the appearance of skeletal lesions in patients affected by Sandhoff disease. 相似文献
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Four aldohexoses were individually subjected to the reagent mixture and temperature cited in the title; in each case, the 2,2-dimethoxypropane was present in only a small molar excess and the p-toluenesulfonic acid was used in trace amounts. D-Mannose (1) afforded the known 2,3:5,6-di-O-isopropylidene-D-mannofuranose (2) in significantly higher yield than when the reaction was conducted at room temperature. The other three aldoses, however, gave products markedly different from those formed under the milder conditions. 2-Acetamido-2-deoxy-D-mannose (3) gave a mixture of products from which methyl 2-acetamido-2-deoxy-2,3-N,O-isopropylidene-5,6-O-isopropylidene-α-D-mannofuranoside (4), 2-acetamido-2-deoxy-2,3-N,O-isopropylidene-5,6-O-isopropylidene-D-mannofuranose (5a), and methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-α-D-mannofuranoside (6a) were isolated. 2-Acetamido-2-deoxy-D-galactose (11) gave compounds identified as methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-galactofuranoside (12a) and methyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-galactopyranoside (13a). 2-Acetamido-2-deoxy-D-glucose (16) afforded methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside (17a) and methyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranoside (18a). Evidence in support of the structures assigned to these new derivatives is presented. 相似文献
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The antigenic polysaccharide produced by Eubacterium saburreum, strain S29, is composed of (1→6)-linked β-d-glycero-d-galacto-heptopyranosyl residues, all of which are substituted with 6-deoxy-α-d-altro-heptofuranosyl groups at O-2. 相似文献
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The purification and chemical characterisation of the alginate present in extracellular material produced by mucoid strains of Pseudomonas aeruginosa 总被引:17,自引:0,他引:17
A rapid ion-exchange method has been used to purify the alginate from the extracellular material of mucoid strains of Pseudomonas aeruginosa isolated from the lungs of cystic fibrosis patients. The structure has been investigated by chemical analysis, infrared spectroscopy, paper chromatography, and gas-liquid chromatography. The alginates contain mainly random or poly(D-mannuronic acid) block structures, and are highly acetylated. The relative viscosity is not correlated with the ratio of D-mannuronic acid to L-guluronic acid residues, or the degree of acetylation. The chemical/physical properties of the alginate from P. aeruginosa are considered in the context of the growth of the organism in the lung. 相似文献
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The tautomeric composition of a solution of ammonium 3-deoxy-d-manno-octulosonate (KDO, 1a) in D2O at 28° was assessed by means of 13 C-F.t.-n.m.r. spectroscopy. The results revealed the presence of 6?0 and 11 % of the α and β anomers of the pyranose, and 20 and 9 % of the two furanoses, and suggested, but did not unequivocally prove, that the major furanose form is the α anomer. To facilitate interpretation of the spectral results for 1, ammonium 3,5-dideoxy-d-arabino(or ribo)-octulosonate (3a) was prepared by the reaction of 5-deoxy-d-erythro-pentose with sodium oxalacetate at pH 11. A chromatographically homogeneous, noncrystalline sample of 3 was obtained by lyophilization, and characterized as its (4-nitrophenyl)hydrazone (m.p. 162-163°). The 13C-n.m.r. spectrum of a solution of 3a in D2O revealed it to be substantially all in the α-pyranose form. No signals were obtained for the possible 1,4-lactone of 3. As the 1,5-lactone and furanose forms are impossible for 3, it exhibited no signals analogous to those attributed to furanoid 1. On the basis of these results for 3, the two lactone forms of 1 were excluded from consideration, and the three pairs of 13C-n.m.r. signals observed at ≈45, 86, and 104 p.p.m. were assigned to the furanose forms of 1. 相似文献