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1.
Membrane fractions and digitonin-solubilized enzymes prepared from stem segments isolated from the third internode of etiolated pea seedlings (Pisum sativum L. cv. Alaska) catalyzed the synthesis of a -1,4-[su14C]mannan from GDP-d-[U-14C]-mannose, a mixed -1,3- and -1,4-[14C]glucan from GDP-d-[U-14C]-glucose and a -1,4-[14C]-glucomannan from both GDP-d-[U-14C]mannose and GDP-d-[U-14C]glucose. The kinetics of the membrane-bound and soluble mannan and glucan synthases were determined. The effects of ions, chelators, inhibitors of lipid-linked saccharides, polyamines, polyols, nucleotides, nucleoside-diphosphate sugars, acetyl-CoA, group-specific chemical probes, phospholipases and detergents on the membrane-bound mannan and glucan synthases were investigated. The -glucan synthase had different properties from other preparations which bring about the synthesis of -1,3-glucans (callose) and mixed -1,3- and -1,4-glucans and which use UDP-d-glucose as substrate. It also differed from xyloglucan synthase because in the presence of several concentrations of UDP-d-xylose in addition to GDP-d-glucose no xyloglucan was formed. Using either the membrane-bound or the soluble mannan synthase, GDP-d-glucose acted competitively in the presence of GDP-d-mannose to inhibit the incorporation of mannose into the polymer. This was not due to an inhibition of the transferase activity but was a result of the incorporation of glucose residues from GDP-d-glucose into a glucomannan. The kinetics and the composition of the synthesized glucomannan depended on the ratio of the concentrations of GDP-d-glucose and GDP-d-mannose that were available. Our data indicated that a single enzyme has an active centre that can use both GDP-d-mannose and GDP-d-glucose to bring about the synthesis of the heteropolysaccharide.Abbreviations CHAPS 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate - CHAPSO 3-[(3-cholamidopropyl)-dimethylammonio]-2-hydroxy-1-propanesulfonate - CHD 1,2-cyclohexanedione - CDP cytidine 5-diphosphate - EGTA ethylene glycol-bis(-aminoethyl ether) N,N,N,N-tetraacetic acid - GDP guanosine 5-diphosphate - NAI N-acetyl-imidazole - NEM N-ethylmaleimide - PGO phenylglyoxal This work has been made possible by grants of M.A.F. and M.U.R.S.T. 40% of Italy. Dr. A. Zuppa wishes to thank the C.N.R. of Italy for his research scolarship.  相似文献   

2.
Particulate membrane preparations have been isolated from cambial cells, and from differentiating and differentiated xylem cells of the main stem of pine trees. These preparations synthesise a 14 glucomannan from guanosine 5-diphosphate-mannose. The polysaccharide and the synthase have been characterized and the Km and Vmax for the synthase determined as 85 M and 52.9 M·min-1, respectively. The enzymic activity was inhibited by the addition of guanosine 5-diphosphate-D-glucose so that the presence of an epimerase on the particulate fraction in conjunction with the synthase probably allowed the heteropolymer to be formed with the optimal ratio of the concentrations of the nucleoside-diphosphate sugar donors. No evidence for a polyprenyl-phosphate derivative as an intermediate during the polymer synthesis was obtained. Part of the control mechanism for the deposition of the large amounts of the glucomannan during the secondary thickening of the tracheids of the vascular system is by an increase in the amount of synthase activity at the endomembrane system of the cells. This probably occurs by an increase in the amount of enzyme which is modulated by gene regulation during differentiation.Abbreviations GDP guanosine 5-diphosphate - GLC gasliquid chromatography  相似文献   

3.
Summary In the colonic epithelium of the chicken, glycoconjugates have been studied by means of selected histochemical methods of light and electron microscopy. According to the results obtained, most of the colonic goblet cells contained acidic and neutral glycoconjugates with sulphate and vicinal diol groupings, -D-mannose and -D-glucose residues and sialic acid-galactose dimers. These goblet cells were found to undergo changes in histochemical reactivity during upward migration along the crypts; -D-mannose and -D-glucose residues and terminal sialic acidgalactose dimers increased in amount. The striated border of the colonic columnar cells has, likewise, been found to contain such glycoconjugates as were similar in reactivity to those of the goblet cells. The histophysiological significances of glycoconjugates involved in the chicken colonic epithelium have been discussed with special reference to the functional activities of the carbohydrates.  相似文献   

4.
On aerobic incubation of rat cerebral cortex slices with anomers ofd-glucose and with 2-deoxy-d-glucose (2DG) for 5 min, the disappearance of -d-glucose from the incubation mixture was greater than that of -d-glucose and both anomers had a greater rate of disappearance than that of 2DG. In addition, there were significantly greater consumption of oxygen and production of lactate with the -anomer than with the -anomer. In similar experiments with3H-labeledd-glucose anomers and [1-3H]-3-O-methyl-d-glucose (3MG), the accumulation of [1-3H]--d-glucose (up to 5 min) by rat cerebral cortex slices was greater than that of [1-3H]--d-glucose. Although initially lower than that of the anomers, the accumulation of [1-3H]-3MG increased at a greater rate and, by 5 min of incubation, was greater than that of both glucose anomers. This preferential accumulation was seen to disappear when the slices were preincubated with 2DG (hexokinase inhibitor) or when the temperature of incubation was reduced to 20°C. Under those conditions the data with the glucose anomers were similar to those obtained with 3MG. Our data then suggested that the greater accumulation of -d-glucose than of -d-glucose by the slices was probably not due to differences in transport through brain cell membranes but rather to the preferential metabolism of the -d-glucose.  相似文献   

5.
Negative-ion fast atom bombardment tandem mass spectrometry has been used in the characterization of non-, mono-, di- and trisulfated disaccharides from heparin and heparan sulfate. The positional isomers of the sulfate group of monosulfated disaccharides were distinguished from each other by negative-ion fast atom bombardment tandem mass spectra, which provide an easy way of identifying the positional isomers. This fast atom bombardment collision induced dissociation mass spectrometry/mass spectrometry technique was also applied successfully to the characterization of di- and trisulfated disaccharides.Abbreviations FABMS fast atom bombardment mass spectrometry - CID collision induced dissociation - MIKE mass analysed ion kinetic energy - MS/MS mass spectrometry/mass spectrometry - HPLC high performance liquid chromatography - UA d-gluco-4-enepyranosyluronic acid - CS chondroitin sulfate - DS dermatan sulfate - HA hyaluronan - Hep heparin - HS heparan sulfate - UA(14) GlcNAc 2-acetamido-2-deoxy-4-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose - UA(14)GlcNAc6S 2-acetamido-2-deoxy-4-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA2S(14)GlcNAc 2-acetamido-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-glucose - UA2S(14)GlcNAc6S 2-acetamido-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA(14)GlcN6S 2-amino-2-deoxy-4-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA2S(14)GlcN 2-amino-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-glucose - UA2S(14)GlcN6S 2-amino-2-deoxy-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA(14)GlcNS 2-deoxy-2-sulfamino-4-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose - UA(14)GlcNS6S 2-deoxy-2-sulfamino-4-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA2S(14)GlcNS 2-deoxy-2-sulfamino-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-glucose - UA2S(14)GlcNS6S 2-deoxy-2-sulfamino-4-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-glucose - UA(13)GalNAc 2-acetamido-2-deoxy-3-O-(-d-Gluco-4-enepyranosyluronic acid)-d-galatose - UA(13)GalNAc4S 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose - UA(13)GalNAc6S 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose - UA2S(13)GalNAc 2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-galactose - UA2S(13)GalNAc4S 2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose - UA2S(13)GalNAc6S 2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose - UA(13)GalNAcDiS 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4,6-di-O-sulfo-d-galactose - UA(13)GlcNAc 2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose.  相似文献   

6.
Cell-free extracts from Rhus typhina L. (staghorn sumach) leaves were found to catalyze the transfer of the galloyl moiety of -glucogallin (1-O-galloyl--D-glucose) to 1,6-di-O-galloyl--D-glucose, resulting in the specific formation of 1,2,6-tri-O-galloyl--D-glucose, an intermediate of gallotannin biosynthesis. The reaction product was unequivocally identified by co-chromatography with authentic references using reversed-phase high-performance liquid chromatography and by 1H-nuclear-magnetic-resonance spectroscopy.Abbreviations HPLC high-performance liquid chromatography - NMR nuclear magnetic resonance  相似文献   

7.
Recombinant Penicillium citrinum -1,2-mannosidase, expressed in Aspergillus oryzae, was employed to carry out regioselective synthesis of -d-mannopyranosyl-(12)-d-mannose. Yields (w/w) of 16.68% disaccharide, 3.07% trisaccharide and 0.48% tetrasaccharide were obtained, with 12 linkages present at 98.5% of the total linkages formed. Non-specific -mannosidase from almond was highly efficient in reverse hydrolysis and oligosaccharide yields of 45–50% were achieved. The products of the almond mannosidase were a mixture of disaccharides (30.75%, w/w), trisaccharides (12.26%, w/w) and tetrasaccharides (1.89%, w/w) with 12, 13 and 16 isomers. -1,2-linkage specific mannosidase from P. citrinum and -1,6-linkage-specific mannosidase from Aspergillus phoenicis were used in combination to hydrolyse the respective linkages from the mixture of isomers, resulting in -d-mannopyranosyl-(13)-d-mannose in 86.4% purity. The synthesised oligosaccharides can potentially inhibit the adhesion of pathogens by acting as "decoys" of receptors of type-1 fimbriae carried by enterobacteria.  相似文献   

8.
N-acetylhexosaminidase fromNocardia orientalis catalysed the synthesis of lacto-N-triose II glycoside (-d-GlcNAc-(1-3)--d-Gal-(1-4)--d-Glc-OMe,3) with its isomers -d-GlcNAc-(1-6)--d-Gal-(1-4)--d-Glc-OMe (4) and -d-Gal-(1-4)-[-d-GlcNAc-(1-6)]--d-Glc-OMe (5) throughN-acetylglucosaminyl transfer fromN,N-diacetylchitobiose (GlcNAc2) to methyl -lactoside. The enzyme formed the mixture of trisac-charides3, 4 and5 in 17% overall yield based on GlcNAc2, in a ratio of 20:21:59. Withp-nitrophenyl -lactoside as an acceptor, the enzyme also producedp-nitrophenyl -lacto-N-trioside II (-d-GlcNAc-(1-3)--d-Gal-(1-4)--d-Glc-OC6H4NO2-p,6) with its isomers -d-GlcNAc-(1-6)--d-Gal-(1-4)--d-Glc-OC6H4NO2-p (7) and -d-Gal-(1-4)-[-d-GlcNAc-(1-6)]--d-Glc-OC6H4NO2-p (8). In this case, when an inclusion complex ofp-nitrophenyl lactoside acceptor with -cyclodextrin was used, the regioselectivity of glycosidase-catalysed formation of trisaccharide glycoside was substantially changed. It resulted not only in a significant increase of the overall yield of transfer products, but also in the proportion of the desired compound6.Abbreviations GlcNAc2 2-acetamido-2-deoxy--d-glucopyranosyl-(1-4)-2-acetamido-2-deoxy-d-glucose - NAHase N-acetylhexosaminidase - -CD -cyclodextrin  相似文献   

9.
Two new asterosaponins, (20R)-3-O--D-(2-O-methylxylopyranosyl)-24-propylcholest-4-ene-3,6,8,15,16,29-hexaol (sanguinoside A) and (20R,24S)-3-O--D-(2,3,4-tri-O-methylxylopyranosyl)-5-cholestane-3,4,6,8,15,24-hexaol (sanguinoside B), were isolated from two species of Pacific Far Eastern Starfish Henricia sanguinolenta and H. leviuscula leviuscula, collected in the Sea of Okhotsk. Both glycosides contain aglycones with pentahydroxysteroid nuclei of similar structures, which are substituted at the 3-hydroxy group with differently methylated -D-xylosyl residues. Sanguinoside A has an unusual structure of its aglycone side chain, whereas sanguinoside B has a unique permethylated carbohydrate chain. In addition, laevisculoside G, a known glycoside, was identified in the H. leviuscula starfish. The structures of the isolated glycosides were established by interpreting their spectral data and by comparing their spectral characteristics with those of known compounds.  相似文献   

10.
Summary In the secretory epithelium of the chicken mandibular gland, glycoconjugates have been studied by means of histochemical methods of light and electron microscopy. In light microscopy, a series of histochemical procedures have been employed which included lectin—peroxidase—diaminobenzidine methods and a digestion technique with neuraminidase or-amylase. In electron microscopy, a battery of methods were used that corresponded to those employed in light microscopy. In the secretory cells of the chicken mandibular gland, vicinal diol- and sulphate-containing glycoconjugates with sialic acid,-d-mannose,-d-glucose and-d-galactose residues were visualized and the possible histophysiological significances of such glycoconjugates were discussed with special reference to the functions of the salivary gland.  相似文献   

11.
The induction by d,l-nicotine of the enantiozymes 6-hydroxy-L-nicotine oxidase and 6-hydroxy-D-nicotine oxidase in Archrobacter oxidans was differently affected by the inhibitors of Escherichia coli gyrase, novobiocin and nalidixic acid. These compounds inhibited 6-hydroxy-L-nicotine oxidase induction slightly, but led to an increase in the level of 6-hydroxy-D-nicotine oxidase activity. Furthermore, the specific repression by glucose of 6-hydroxy-D-nicotine oxidase synthesis was not abolished by the addition of cAMP but by that of novobiocin.Abbreviations 6-HDNO 6-hydroxy-D-nicotine oxidase - 6-HLNO 6-hydroxy-L-nicotine oxidase - cAMP cyclic 3,5-adenosine monophosphate - Enzymes Adenylate cyclase - ATP pyrophosphate-lyase (cyclizing) (EC 4.6.1.1) - cAMP-phosphodiesterase 3:5-cyclic-nucleotide 5-nucleotido-hydrolase (EC 3.1.4.17) - DNA gyrase DNA topoisomerase II (EC 5.99) - DNA polymerase deoxynucleosidetriphosphate: DNA desoxynucleotidyl-transferase (EC 2.7.7.7) - 6-hydroxy-L-nicotine oxidase 6-hydroxy-L-nicotine: oxygen oxidoreductase (EC 1.5.3.5) - 6-hydroxy-D-nicotine oxidase 6-hydroxy-D-nicotine: oxygen oxidoreductase (EC 1.5.3.6) - -lactamase penicillin amido--lactamhydrolase (EC 3.5.2.6) - nicotine dehydrogenase nicotine: (acceptor)6-oxidoreductase (hydroxylating) (EC 1.5.99.4)  相似文献   

12.
This report summarizes our current understanding of the heavy chain haplotypes found in our laboratories' rabbits. Independently derived data from several laboratories have been synthesized into a consistent picture of the linked inheritance of allotypic markers found on the different heavy chain classes and subclasses of rabbit immunoglobulins in pedigreed rabbits, including the families of three apparentVH-CH recombinants. In one recombinant, the entire group ofCH markers (C, C, and C) recombined with the set ofVH. Although in the other two recombinants all CH markers may also have recombined as a group, in one of these only IgG and IgACH genes were informative; in the other recombinant, only the IgG allotypes were informative. Some allotypic determinants found on IgM molecules (conformational) appear only when a specific variable region allotype (VHa) is combined with a specific constant region allotype (C). New combinations ofVHa and C allotypes were generated in two of the genetic recombinants and led to new conformational determinants. The gains and losses observed lend support to the hypothesis that the determinants result from conformations generated by the combination of allotype-specificVH and C protein sequences. Conceivably, DNA events that joinVH to diversity (D)- and joining (J)-coding sequences or mRNA processing events that splice J to C could be involved in generating the sequences that form allotype-specific determinants.  相似文献   

13.
Schizosaccharomyces pombe cells grow on d-gluconate as the sole carbon and energy source. d-Gluconate is taken up in symport with protons by a specific symporter, pH being the sole driving force. d-Gluconate uptake is independent of the sugar transporting system (e.g. for d-glucose) and of . The carrier is expressed constitutively, and its activity is not subject to glucose repression. Hence, d-gluconate is a suitable carbon and energy source for growth, when d-glucose or other hexoses have to be eliminated e.g. for selection of mutants deficient in hexose transport.Abbreviations 2-DG 2-deoxy-d-glucose - CCCP carbonylcyanide m-chlorophenylhydrazone - pH pH-gradient - electrical potential difference across the plasma membrane - SD standard deviation - SEM standard error of the mean - TPP+ tetraphenylphosphonium  相似文献   

14.
The activities of -2-l-fucosyltransferase and -3-l-fucosyltransferase were measured in human platelets and leucocytes from normal donors, -2-l-Fucosyltransferase was found in platelets but not in leucocytes. In contrast -3-l-fucosyltransferase was not detected in platelets but was present in leucocytes where it was demonstrated in the neutrophil, monocyte and lymphocyte fractions.  相似文献   

15.
Protein preparations from seeds and seedlings (cotyledons) of rape (Brassica napus subsp. napus [L.] DC.) catalyzed the transfer of sinapic acid from 1-Osinapoyl--glucose to malate in the formation of O-s-inapoylmalate. The enzyme involved, 1-O-sinapoyl--glucose: l-malate O-sinapoyltransferase (SMT; EC 2.3.1), catalyzes the key step in the overall conversion of the seed constituent sinapine (O-sinapoylcholine) to the accumulating O-sinapoylmalate by way of the intermediate 1-O-sinapoyl--glucose. The present paper describes this phenomenon focussing on SMT activity.Abbreviations Sin-Glc 1-O-sinapoyl--glucose - Sin-Mal O-sinapoylmalate - SMT 1-O-sinapoyl--glucose: l-malate sinapoyltransferase (EC 2.3.1) This work was supported by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie and the Ontario Ministry of Agriculture and Food.  相似文献   

16.
The preparation of benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside, which is a key intermediate for chemical synthesis of oligosaccharide components of glycosphingolipids, was achieved by an improved method. The 3-O-p-methoxybenzyl and 3-O-methyl derivatives were prepared from benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside through stannylation. By using benzyl -d-lactoside as starting material, benzyl 3-O-methyl-, 3-O-benzyl- and 3-O-p-methoxybenzyl--d-lactoside were regioselectively synthesized using the same procedure.  相似文献   

17.
-Fructofuranosidase from Aspergillus japonicus MU-2, which produces fructo-oligosaccharides (1-kestose: O--D-fructofuranosyl-(2 1)--D-fructofuranosyl -D-glucopyranoside); and nystose: O--D-fructofuranosyl-(2 1)--D-fructofuranosyl-(2 1)--D-fructofuranosyl -D-glucopyranoside) from sucrose, was immobilized, covalently with glutaraldehyde onto alkylamine porous silica, at high efficiency (64%). Optimum pore diameter of porous silica for immobilization of the enzyme was 91.7 nm. After immobilization, the enzyme's stabilities to temperature, metal ions and proteolysis were improved, while its optimum pH and temperature were unchanged. The highest efficiency of continuous production of fructo-oligosaccharides (more than 60%), using a column packed with the immobilized enzyme, was obtained at 40% to 50% (w/v) sucrose. The half-life of the column during long-term continuous operation at 55°C was 29 days.  相似文献   

18.
Micropropagation of mature Chinese tallow tree (Sapium sebiferum Roxb.)   总被引:1,自引:0,他引:1  
An in vitro propagation technique based on axillary bud proliferation has been developed for matureSapium sebiferum trees. Nodal segments cultured on Murashige and Skoog (MS) medium supplemented with benzyl adenine (1–10 m and -naphthaleneacetic acid (0–0.5 m showed axillary bud proliferation. Shoots proliferated in vitro were multiplied on Murashige and Skoog medium containing 2.5 m benzyl adenine and 0.25 m -naphthaleneacetic acid. Seasonal changes affected the shoot proliferation potential of the initial explant. Shoots were rooted on a half-strength, growth-regulator-free, agar-gelled, MS medium after a 48-h treatment on half-strength MS liquid medium with 10 m indole-3-butyric acid. Rooted plantlets were potted and acclimatized in a growth chamber and then moved to the greenhouse. Four-month-old plants were transplanted to the field.Abbreviations BA Benzyl adenine - IBA Indole-3-butyric acid - 2-ip N6-(-dimethylallylamino)purine - MS Murashige and Skoog (1962) medium - NAA -Naphthaleneacetic acid  相似文献   

19.
Transmannosylation from mannotriose (Man1-4Man1-4Man) to the 4-position at the nonreducing end N-acetylglucosaminyl residue ofN,N-diacetylchitobiose was regioselectively induced through the use of -d-mannanase fromAspergillus niger. The enzyme formed the trisaccharide Man1-4GlcNAc1-4GlcNAc (3.7% of the enzyme-catalysed net decrease ofN,N-diacetylchitobiose) from mannotriose as a donor andN,N-diacetylchitobiose as an acceptor. Mannobiose (Man1-4Man) was also shown to be useful as a donor substrate for the desired trisaccharide synthesis.Abbreviations Man d-mannose - (M n) (n=1–5) -linkedn-mer of mannose - GlcNAc2 2-acetamido-2-deoxy--d-glucopyranosyl-(1–4)-2-acetamido-2-deoxy-d-glucose  相似文献   

20.
-Elimination of peptidorhamnomannans purified from yeast-like and mycelial phases ofSporothrix schenckii released neutral and acidic reduced oligosaccharides that were O linked to serine and/or threonine. Man-(1–2)Man-ol, Rha(1–3)Man(1–2)Man-ol, Rha(1–4)GlcA(1–2)Man(1–2)Man-ol, and Rha(1–4)[Rha(1–2)] GlcA(1–2)Man(1–2)Man-ol were characterized based on methylation analysis, proton magnetic resonance and fast atom bombardment mass spectrometry.Abbreviations FAB fast atom bombardment - GLC gas liquid chromatography - GlcA d-glucopyranosyluronic acid - Man d-mannopyranose - Man-ol d-mannitol - MS mass spectrometry - NMR nuclear magnetic resonance - Rha l-rhamnopyranose  相似文献   

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