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1.
1. The influence of insulin on the metabolism of [1-14C]glucosamine by diaphragm muscle from normal rats and rats rendered diabetic with streptozotocin has been studied. 2. The glucosamine was converted into glucosamine 1-phosphate, glucosamine 6-phosphate, glycogen, lactate and small amounts of other unidentified intermediates. 3. Insulin increased the incorporation of 14C into glycogen in both the normal and diabetic muscle, but did not increase the formation of the glucosamine phosphate esters. 4. The 14C content in the glycogen was present partly as glucose and partly as glucosamine; there was significantly more [14C]glucose in the glycogen of the diabetic muscle than in that of the normal muscle.  相似文献   

2.
The glycerol teichoic acid of walls of Staphylococcus lactis I3   总被引:13,自引:10,他引:3  
1. The teichoic acid from walls of Staphylococcus lactis I3 was isolated by extraction with trichloroacetic acid and shown to contain glycerol, N-acetylglucosamine, phosphate and d-alanine in the molecular proportions 1:1:2:1. The alanine is attached to the polymer through ester linkages. 2. Hydrolysis with acid gave alanine, glucosamine and glycerol diphosphates. Under mild acid conditions a repeating unit was produced; this consists of glycerol diphosphate joined through a phosphodiester group to N-acetylglucosamine. 3. Hydrolysis with alkali gave glycerol diphosphates, saccharinic acid and two phosphodiesters containing glucosamine whose structures were elucidated; these both contain glucosamine 1-phosphate, and N-acetylglucosamine 1-phosphate was isolated by a degradative procedure. 4. The unusual properties of the teichoic acid are explained by a polymeric structure in which N-acetylglucosamine 1-phosphate is attached through its phosphate to glycerol phosphate. 5. The biosynthetic implications of this structure are discussed.  相似文献   

3.
Rat liver plasma membranes, as fractionated by sodium dodecylsulfate/polyacrylamide gel electrophoresis, have been examined for the incorporation in their subunits of radioactive leucine, glucosamine and fucose. Specific spectra were obtained. In contrast to leucine, where the activity is distributed in many peaks all over the fractions, the glucosamine and fucose activities are found principally in the high molecular weight region. The relative rates of degradation of the glycoprotein components of the plasma membrane have been measured in normal liver using the double isotope technique. A marked heterogeneity of degradation was observed among the different subunits and a correlation between the rate of degradation and the size of the labelled subunits was found with glucosamine and fucose as well with leucine. This suggests a similar mode for the degradation of these membrane components.  相似文献   

4.
Rat liver plasma membranes, as fractionated by sodium dodecylsulfate/polyacrylamide gel electrophoresis, have been examined for the incorporation in their subunits of radioactive leucine, glucosamine and fucose. Specific spectra were obtained. In contrast to leucine, where the activity is distributed in many peaks all over the fractions, the glucosamine and fucose activities are found principally in the high molecular weight region.The relative rates of degradation of the glycoprotein components of the plasma membrane have been measured in normal liver using the double isotope technique. A marked heterogeneity of degradation was observed among the different subunits and a correlation between the rate of degradation and the size of the labelled subunits was found with glucosamine and fucose as well as with leucine. This suggests a similar mode for the degradation of these membrane components.  相似文献   

5.
The effects of insulin and epinephrine on the phosphorylation of glycogen synthase were investigated using rat hemidiaphragms incubated with [32P]phosphate. Antibodies against rabbit skeletal muscle glycogen synthase were used for the rapid purification of the 32P-labeled enzyme under conditions that prevented changes in its state of phosphorylation. The purified material migrated as a single radioactive species (Mapp = 90,000) when subjected to electrophoresis in sodium dodecyl sulfate. Insulin decreased the [32P]phosphate content of glycogen synthase. This effect occurred rapidly (within 15 min) and was observed with physiological concentrations of insulin (25 microunits/ml). The amount of [32P]phosphate removed from glycogen synthase by either different concentrations of insulin or times of incubation with the hormone was well correlated to the extent to which the enzyme was activated. Epinephrine (10 microM) inactivated glycogen synthase and increased its content of [32P]phosphate by about 50%. Cleavage of the immunoprecipitated enzyme with cyanogen bromide yielded two major 32P-labeled fragments of apparent molecular weights equal to approximately 28,000 and 15,000. The larger fragment (Fragment II) displayed electrophoretic heterogeneity similar to that observed with the corresponding CNBr fragment (CB-2) from purified rabbit skeletal muscle glycogen synthase phosphorylated by different protein kinases. Epinephrine increased [32P]phosphate content of both fragments; however, the increase in the radioactivity of the smaller fragment (Fragment I) was more pronounced. Insulin decreased the amount of [32P] phosphate present in Fragments I and II by about 40%. The results presented provide direct evidence that both insulin and epinephrine control glycogen synthase activity by regulating the phosphate present at multiple sites on the enzyme.  相似文献   

6.
Sheaths isolated from Gloeobacter violaceus were found to be composed of a major polysaccharide moiety (glucose, galactose, rhamnose, mannose, arabinose), a protein moiety, and negatively charged components (glucuronic acids, phosphate, sulfate). Outer membrane polypeptide patterns were dominated by two major peptidoglycan-associated proteins (Mr 62,000 and 53,000). Lipopolysaccharide constituents were glucosamine, 3-hydroxy fatty acids (3-OH-14:0, anteiso-3-OH-15:0, 3-OH-16:0, 3-OH-18:0), carbohydrates, and phosphate. A1-type peptidoglycan and non-peptidoglycan components (mannosamine, glucose, mannose, and glucosamine) indicated the presence of a peptidoglycan-polysaccharide complex in the cell walls of Gloeobacter violaceus.Abbreviations A2pm diaminopimelic acid - ATCC American Type Culture Collection - CE cell envelope - CM cytoplasmic membrane - CW cell wall - dOcla 3-deoxy-d-manno-2-octulosonic acid - GalN galactosamine - GlcN glucosamine - GlcUA glucuronic acid - HF hydrofluoric acid - LPS lipopolysaccharide - ManN mannosamine - M relative molecular mass - MurN muramic acid - MurN-6-P muramic acid-6-phosphate - OMe O-methyl - PAGE polyacrylamide gel electrophoresis - PCC Pasteur Culture Collection - SDS sodium dodecyl sulfate - SH sheath  相似文献   

7.
The effect of different extraction procedures on the yields of water-soluble and water-insoluble glycogen fractions from a number of Saccharomyces strains was studied by using a specific method for glycogen determination. The similarity of the yields obtained by the different procedures showed that neither form of glycogen is an artifact, and variations in the relative amounts of glycogen in the two fractions during cell growth and in different yeast strains suggest that they represent different pools of storage material with specific roles in cell development and differentiation. A proportion of the water-insoluble glycogen fraction, solubilized by mechanical agitation, was shown to be strongly associated with a beta-glucan-like polysaccharide that may be a cell wall component.  相似文献   

8.
Protein-polysaccharides of pig laryngeal cartilage   总被引:23,自引:18,他引:5  
1. Protein-polysaccharides of chondroitin 4-sulphate were extracted with neutral calcium chloride from pig laryngeal cartilage that was not completely homogenized. The protein-polysaccharides were purified by precipitation with 9-aminoacridine. On zone electrophoresis in compressed glass fibre at pH7.2 it was separated into two fractions, although two distinct zones were not obtained. These fractions, which had already been shown to differ in their antigenic determinants, also differed considerably in amino acid composition, total protein, hexose and glucosamine contents. 2. The fraction of higher mobility contained approx. 2% of protein and only traces of glucosamine. Serine and glycine accounted for over half the total amino acid residues, but aromatic, basic and sulphur-containing amino acids were not detected. The weight-average molecular weight, determined by sedimentation, was 230000. 3. Assuming that there was the same sequence of neutral sugars at the linkage points as in PP-L fraction (protein-polysaccharide light fraction), the approximate molar ratio of hexose to serine suggested that most of the serine residues were linked to chondroitin sulphate chains. Support for this was derived from the agreement between the weight-average molecular weight of the chondroitin sulphate-peptide after proteolysis, and the chain weight calculated from its serine content. The chain weight based on the serine content of the fraction of higher electrophoretic mobility was approximately similar. 4. In contrast, the fraction of lower electrophoretic mobility resembled PP-L fraction in its amino acid composition, protein and glucosamine contents. The presence of glucosamine, together with the higher hexose content, suggested that this fraction contained some keratan sulphate. 5. The relatively low molecular weight of the fraction of higher mobility enabled it to be extracted without complete disintegration of the cartilage. The unlikelihood of its being produced by autolytic enzymes is discussed.  相似文献   

9.
The reasons for the occurrence of trace amounts of glucosamine in animal liver glycogens have been explored. Human liver glycogen is now shown to contain this amino sugar. Galactosamine, known to be the source of the incorporated glucosamine, is found to give rise to glucosamine in glycogen when administered orally, or as the N-acetyl derivative. The rabbit can also incorporate glucosamine into kidney glycogen but not into glycogen in heart or skeletal muscle. These experiments led to the discovery that glucosamine is incorporated into rabbit liver glycogen in such a way that there is intermolecular heterogeneity in the content of glucosamine, suggesting that there exists more than one pool of liver glycogen.  相似文献   

10.
Hydrophobic envelope proteins were extracted by phenol from a glucosamine- and leucine-requiring mutant of Escherichia coli K-12 (E-110). Three protein fractions labelled with D-[1-1 4C]glucosamine and L-[4,5-3H]leucine were obtained by electrophoretic separation. Envelope were isolated from cells labeleed with D-[1-1 4C]glucosamine—HCL and acid hydrolyzed. At least 68% of the radioactivity was recovered as glucosamine and glucose with no random distribution of label. Fingerprinting of pronase digests of glucosamine-labelled proteins showed four radioactive spots associated with peptides. Te glycoproteins were pronase- and trypsin-sensitive and had apparent molecular weights of 11 000 (fast mobility), 35 000 (intermediate mobility) and 62 000 (slow mobility) as estimated by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. The two heavier fractions were labelled with meso-diamino[1,7-1 4C2]pimelic acid, while ortho[3 2P]phosphate was not incorporated into any fraction. The glucosamine radioactivity of the fast fraction underwent rapid changes upon a chase with non-radioactive glucosamine. Using a Sephadex LH-20 column, the radioactive proteins were separated from the phenol and subsequently fractionated on a DEAS-cellulose column. The DEAE-cellulose fractions were distinct from each other in the number and composition of protein bands, when analyzed by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. Radioactive bands with intermediate and fast electrophoretic mobilities were found in separate DEAE-cellulose fractions.  相似文献   

11.
Lipopolysaccharides (LPSs) isolated from phase I and phase II Coxiella burnetii (LPS I and LPS II, respectively) were analyzed for chemical compositions, molecular heterogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunological properties. The yields of crude phenol-water extracts from phase I cells were roughly three to six times higher than those from phase II cells. Purification of LPSs by ultracentrifugation gave similar yields for both LPS I and LPS II. Purified LPS I and LPS II contained roughly 0.8 and 0.6% protein, respectively. The fatty acid constituents of the LPSs were different in composition and content, with branched-chain fatty acids representing about 15% of the total. beta-Hydroxymyristic acid was not detected in either LPS I or LPS II. A thiobarbituric acid-periodate-positive compound was evident in the LPSs; however, this component was not identified as 3-deoxy-D-mannooctulosonic acid by gas and paper chromatographies. LPS II contained D-mannose, D-glucose, D-glyceromannoheptose, glucosamine, ethanolamine, 3-deoxy-D-mannooctulosonic acid-like material, phosphate, and fatty acids. LPS I contained the unique disaccharide galactosaminuronyl glucosamine and nine unidentified components in addition to the components of LPS II. The hydrophobic, putative lipid A fraction of LPS I and LPS II contained the above constituents, but the hydrophilic fraction was devoid of ethanolamine. The LPS I disaccharide galactosaminuronyl glucosamine was found in both fractions of the acetic acid hydrolysates. Analysis of LPSs by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining indicated that LPS II was composed of only one band, whereas LPS I consisted of six or more bands with irregular spacing. Ouchterlony immunodiffusion tests demonstrated that LPS I reacted with phase I but not with phase II whole-cell hyperimmune antibody, and LPS II reacted neither with phase I nor phase II hyperimmune antibody. From these results, it was concluded that the chemical structures of LPSs from C. burnetii were different from those of the LPSs of gram-negative bacteria; however, the LPS structural variation in C. burnetii may be similar to the smooth-to-rough mutational variation of saccharide chain length in gram-negative bacteria.  相似文献   

12.
Equilibrium density-gradient ultracentrifugation in caesium choride and caesium sulphate has been used in the isolation and fractionation of the glycoproteins specific for blood-group P1 from hydatid cyst fluids. The fractions obtained have distinct and systematic differences specifically related to their buoyant densities, chemical compositions and specific-activities for group P1. High levels of specific-activity were maintained over a large range of chemical compositions. The peptide content varied systematically from 2.5% for the densest fraction to 37% for the least dense fraction. The amino acid composition was essentially constant over all fractions. The proportion of glucosamine decreased and the proportions of galactosamine, mannose and glucose increased with increasing peptide content of the fractions. The data presented suggest the present of oligosaccharide side-chains of various lengths and compositions and/or the presence of oligosaccharide side-chains with very different chemical compositions, of which only some are associated with the specificity for group P1. The properties of the glycoproteins from hydatid cyst fluids have been compared with those of the glycoproteins from human ovarian cysts. Although some similarities have been demonstrated there are significant differences.  相似文献   

13.
The aim of this study was to characterize the extracellular polysaccharides (EPS) released by a freshwater Thalassiosira sp. (Bacillariophyceae) and evaluate their degradation by heterotrophic microbial populations from the same habitat of Thalassiosira sp., a tropical eutrophic reservoir. The EPS were purified by anion exchange column chromatography, the monosaccharide composition was determined by GC, and the linkages of the monosaccharides by GC‐MS. The EPS is a mannose‐rich heteropolysaccharide composed of two different acidic fractions. Both of these fractions are composed of mannose, rhamnose, fucose, xylose, galactose, glucose, glucuronic acid, and N‐acetyl glucosamine but with different proportions. N‐acetyl galactosamine occurs only in fraction 1 and galacturonic acid only in fraction 2. We monitored the concentrations of the monosaccharides in the EPS during its degradation using pulse amperometric detection in an HPLC. The decay patterns of the monosaccharides were varied and the deoxy sugars, fucose and rhamnose, were degraded at a slower rate than the other components, increasing their relative concentrations and the hydrophobic feature of the EPS. The possibility of a selective degradation, which enhances the stickiness of the EPS, promoting transparent exopolymeric particles and aggregate formation, is discussed based on the literature data.  相似文献   

14.
1. Four of the known components of wall preparations of vegative cells of Bacillus licheniformis N.C.T.C. 6346 have been isolated free of each other after successive treatments of the walls with trichloroacetic acid and lysozyme: (a) a mucopeptide consisting of glucosamine, muramic acid, alphain-diaminopimelic acid, glutamic acid and alanine in the molar proportions 1.0:0.8:1.0:1.2:1.7; (b) an insoluble protein; (c) teichoic acid containing phosphorus and glucose in equimolar amounts; (d) teichuronic acid containing equimolar amounts of N-acetylgalactosamine and glucuronic acid, as found by Janczura, Perkins & Rogers (1961). 2. Evidence has been obtained for the presence in the soluble fraction obtained by lysozyme treatment of whole walls of a stable covalent complex of the teichoic acid and the mucopeptide components. 3. The molar ratio of phosphorus to glucose in the teichoic acid present in intact walls or the soluble fractions obtained by extraction of the walls with lysozyme or trichloroacetic acid is 1.0:0.25, in contrast with values of about unity obtained for the purified teichoic acid. 4. Intact walls have been shown to contain polyribitol phosphate chains bearing different amounts of glucose substituents. 5. Trichloroacetic acid extracts of walls also contain polyribitol phosphate compounds of different chain lengths. Dialysis of trichloroacetic acid extracts removes the short chains of polyribitol phosphate that have been found to carry only very low amounts of glucose side chains. By contrast, the longer chains present in the non-diffusible fraction contain phosphorus and glucose in almost equimolar amounts.  相似文献   

15.
Glycogen synthase I (UDP glucose: glycogen alpha-4-glycosyltransferase, EC2.4.1.11) of the tapeworm Hymenolepis diminuta is the form of the enzyme which is active in vivo, while the D-form represents an inactive "storage form." Utilizing the differential effect of inorganic phosphate (Pi) on the I and D-forms, the ratio of the 2 forms in vivo has been determined under conditions of starvation of the host and refeeding of the parasite with glucose. This procedure reveals that conversion of the inactive D-form to the active I-form takes place when glycogen-depleted worms are incubated in glucose. The activity of glycogen synthase I also is affected by the molecular weight of the primer glycogen. With certain molecular weight fractions, enzymatic activity is higher than with others. This specificity of the glycogen primer could explain the relatively low concentrations of those molecular weight fractions which confer the highest synthase activity.  相似文献   

16.
Rat adipocytes were incubated with [32P]phosphate to label glycogen synthase, which was rapidly immunoprecipitated from cellular extracts and cleaved using either CNBr or trypsin. All of the [32P]phosphate in synthase was recovered in two CNBr fragments, denoted CB-1 and CB-2. Isoproterenol (1 microM) rapidly decreased the synthase activity ratio (-glucose-6-P/+glucose-6-P) and stimulated the phosphorylation of both CB-1 and CB-2 by approximately 30%. Insulin opposed the decrease in activity ratio and blocked the stimulation of phosphorylation by isoproterenol. Incubating cells with insulin alone changed the 32P content of neither CB-1 nor CB-2. Trypsin fragments were separated by reverse phase liquid chromatography and divided into peak fractions, denoted F-I-F-VII in order of increasing hydrophobicity. F-V contained almost half of the [32P]phosphate and was phosphorylated when synthase was immunoprecipitated from unlabeled fat cells and incubated with [gamma-32P]ATP and the cAMP-independent protein kinase, FA/GSK-3. That F-V also had the same retention time as the skeletal muscle synthase fragment containing sites 3(a + b + c) suggests that it contains sites 3. Muscle sites 1a, 5, 1b, and 2 eluted with F-I, F-II, F-VI, and F-VII, respectively. F-V was increased approximately 25% by isoproterenol, but the largest relative increases were observed in F-I (4-fold), F-III (4-fold), and F-VI (2-fold). These results indicate that beta-adrenergic receptor activation results in increased phosphorylation of multiple sites on glycogen synthase. Insulin plus glucose decreased the overall 32P content of synthase by approximately 30%, with the largest decrease (40%) occurring in F-V. Without glucose, insulin decreased the [32P]phosphate in F-V by 17%, an effect which was balanced by increases in F-I, F-II, and F-III so that no net change in the total 32P contents of the fractions was observed. Thus, activation of glycogen synthase by the glucose transport-independent pathway seems to involve a redistribution of phosphate in the synthase subunit.  相似文献   

17.
Composition of O-antigenic lipopolysaccharides from Enterobacter cloacae   总被引:2,自引:0,他引:2  
Analyses have been carried out on lipopolysaccharides (LPS) from 14 strains of Enterobacter cloacae representing different O serotypes. All of the products appeared to have a composition and architecture typical of enterobacterial LPS, but points of interest include the absence of phosphate residues from the core oligosaccharide, the presence of both L-glycero-D-mannoheptose and D-glycero-D-mannoheptose (ratio usually about 4:1), and the presence in lipid A of small amounts of fatty acids with odd numbers of carbon atoms (mainly C13) in addition to tetradecanoic acid and 3-hydroxytetradecanoic acid. Monosaccharides identified as components of polymeric fractions from the LPS were glucose, galactose, mannose, rhamnose, glucosamine, galactosamine, fucosamine, and galacturonic acid. Most polymeric fractions also probably contained an O-acetyl substituent. Closely similar chemotypes found for the polymeric fractions from the LPS of cross-reacting serotypes support the view that these fractions contain the O-antigenic determinants and represent the side chains of the LPS.  相似文献   

18.
By cytofluorometry employing the cytofluorometric PAS reaction, a study was made of the total glycogen and of its two fractions in liver parenchymal cells, both in the norm and in patients with chronic alcoholism (alcoholic steatosis, chronic alcoholic hepatitis, and mixed forms of alcoholic-viral hepatitis, viral hepatitis with steatosis and also viral hepatitis). The examination was performed on preparations-smears of isolated hepatocytes, obtained from the live puncture liver biopsies. The quantitative analysis has shown the increase in the total glycogen content in hepatocytes of patients with alcoholic hepatitis in comparison with the norm and with chronic viral hepatitis. The transition from a reverse stage--alcoholic steatosis--to alcoholic hepatitis was accompanied by a sharp increase in the total glycogen content and by an obvious change in the ratio of glycogen fractions, towards the hard soluble fraction in liver cells. The quantitative analysis of glycogen fractions in liver cells of patients with chronic alcoholic disease may be an appreciated marker of differential diagnostics of different stages and forms of alcoholic liver disease.  相似文献   

19.
Soluble hexokinase (ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1) was purified from human heart. 1 kg of tissue provided 25 mg hexokinase with a specific activity of 58 units/mg, representing a 1700-fold purification and 47% yield. The purification involved six steps, including affinity chromatography with glucosamine attached to Sepharose. The material was homogeneous according to electrophoresis, gel-filtration and sedimentation in the ultracentrifuge, but gave two main components on electrophoresis in denaturing conditions. From determination of the sedimentation and diffusion coefficients, the relative molecular mass was calculated to be 105 000. The enzyme is monomeric, but glucose 6-phosphate promotes an association to dimers. This effect is reversible and is independent of the concentrations of glucose or inorganic phosphate. The results support the postulate that soluble and mitochondrion-bound hexokinases are identical.  相似文献   

20.
Hydrophobic envelope proteins were extracted by phenol from a glucosamine- and leucine-requiring mutant of Escherichia coli K-12 (E-110). Three protein fractions labelled with D-[1-1 4C]glucosamine and L-[4,5-3H]leucine were obtained by electrophoretic separation. Envelope were isolated from cells labeleed with D-[1-1 4C]glucosamine—HCL and acid hydrolyzed. At least 68% of the radioactivity was recovered as glucosamine and glucose with no random distribution of label. Fingerprinting of pronase digests of glucosamine-labelled proteins showed four radioactive spots associated with peptides. Te glycoproteins were pronase- and trypsin-sensitive and had apparent molecular weights of 11 000 (fast mobility), 35 000 (intermediate mobility) and 62 000 (slow mobility) as estimated by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. The two heavier fractions were labelled with meso-diamino[1,7-1 4C2]pimelic acid, while ortho[3 2P]phosphate was not incorporated into any fraction. The glucosamine radioactivity of the fast fraction underwent rapid changes upon a chase with non-radioactive glucosamine. Using a Sephadex LH-20 column, the radioactive proteins were separated from the phenol and subsequently fractionated on a DEAS-cellulose column. The DEAE-cellulose fractions were distinct from each other in the number and composition of protein bands, when analyzed by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. Radioactive bands with intermediate and fast electrophoretic mobilities were found in separate DEAE-cellulose fractions.  相似文献   

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