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PubMed1966

Relation of polysaccharide content to some biological properties of endotoxins from mutants of Salmonella typhimurium.

Kessel, R. W. I. (Rutgers, The State University, New Brunswick, N.J.), Henry H. Freedman, and Werner Braun. Relation of polysaccharide content to some biological properties of endotoxins from mutants of Salmonella typhimurium. J. Bacteriol. 92:592-596. 1966.-Endotoxins were extracted by the phenol-water procedure from a variety of Salmonella typhimurium mutants with known differences in the composition of their cell wall polysaccharides. The lethality of these preparations for mice proved to be correlated with the complexity of the polysaccharide: endotoxin from the smooth parent strain and from rough strains with several sugars attached to the heptose-phosphate backbone were of high toxicity, whereas endotoxin from a mutant possessing only glucose attached to the heptose-phosphate backbone was less toxic, and endotoxin from a mutant possessing the backbone only was least toxic. All of these mutants yielded endotoxins that were equally capable of protecting mice against subsequent challenge with Pseudomonas aeruginosa. Material obtained from a heptoseless mutant by the phenol-water method proved to be neither toxic nor protective. The apparent dissociation of biological properties that can be achieved with the aid of endotoxin preparations from certain mutants is discussed in terms of possible mechanisms.

Animals↗

PubMed2005

Lipopolysaccharide inner core oligosaccharide structure and outer membrane stability in human pathogens belonging to the Enterobacteriaceae.

In the Enterobacteriaceae, the outer membrane is primarily comprised of lipopolysaccharides. The lipopolysaccharide molecule is important in mediating interactions between the bacterium and its environment and those regions of the molecule extending further away from the cell surface show a higher amount of structural diversity. The hydrophobic lipid A is highly conserved, due to its important role in the structural integrity of the outer membrane. Attached to the lipid A region is the core oligosaccharide. The inner core oligosaccharide (lipid A proximal) backbone is also well conserved. However, non-stoichiometric substitutions of the basic inner core structure lead to structural variation and microheterogeneity. These include the addition of negatively charged groups (phosphate or galacturonic acid), ethanolamine derivatives, and glycose residues (Kdo, rhamnose, galactose, glucosamine, N-acetylglucosamine, heptose, Ko). The genetics and biosynthesis of these substitutions is beginning to be elucidated. Modification of heptose residues with negatively charged molecules (such as phosphate in Escherichia coli and Salmonella and galacturonic acid in Klebsiella pneumoniae) has been shown to be involved in maintaining membrane stability. However, the biological role(s) of the remaining substitutions is unknown.

Cell Membrane↗

PubMed1998

Effects of D-mannoheptulose and its hexaacetate ester upon D-glucose metabolism in rat hepatocytes.

D-mannoheptulose, which inhibits hexokinase isoenzymes in a predominantly competitive manner, has been found to decrease much more modestly D-glucose metabolism in pancreatic islets exposed to a low, as distinct from high, concentration of the hexose. In the present study, which aimed at investigating the factor(s) possibly responsible for such a phenomenon, a comparable situation was found to prevail in rat hepatocytes. However, when the hexaacetate ester of D-mannoheptulose was used instead of the unesterified heptose, the relative extent of inhibition of D-[5-3H]glucose utilization and D-[U-14C]glucose conversion to 14C-labelled acidic metabolites was comparable in hepatocytes exposed to either 1.7 or 8.3 mM D-glucose. Moreover, at the low D-glucose level, the incorporation of 3-O-methyl-D-glucose (6.6 mM) into the incubation medium increased the inhibitory action of unesterified D-mannoheptulose upon D-glucose metabolism. These findings suggest that an insufficient uptake of the heptose accounts, in part at least, for its poor efficiency as inhibitor of D-glucose catabolism in liver, and presumably islet cells exposed to low concentrations of the hexose.

3-O-Methylglucose↗

PubMed2001

D-mannoheptulose phosphorylation by hexokinase isoenzymes.

D-mannoheptulose is a specific inhibitor of D-glucose phosphorylation by hexokinase isoenzymes. In the present study, the phosphorylation of this heptose was investigated by either a spectrophotometric or radioisotopic procedure. Using yeast hexokinase, the phosphorylation of 25 mM D-mannoheptulose only represented 0.02% of that of 5 mM D-glucose. Such a percentage was increased to 3.93% in the case of bovine heart hexokinase. In the latter case, the Km for D-mannoheptulose was close to 0.2 mM and both D-glucose (0.1-1.0 mM) and D-glucose 6-phosphate (also 0.1-1.0 mM) inhibited the phosphorylation of the heptose (0.03-0.60 mM). Human B-cell glucokinase also catalyzed the phosphorylation of D-mannoheptulose (0.1 mM), which was now increased in a bell-shaped manner by D-glucose (1.0-20 mM). Likewise, rat parotid gland, liver and pancreatic islet homogenates catalyzed the phosphorylation of D-[3H]mannoheptulose. The results obtained in these three tissues differed from one another by their absolute values (per mg wet wt.), relative values (by reference to the phosphorylation rate of 10 mM D-glucose), and sensitivity to inhibition by D-glucose (10 mM).

Amino Acid Substitution↗

PubMed2001

Uptake of D-mannoheptulose by normal and tumoral pancreatic islet cells.

D-mannoheptulose was recently proposed as a possible tool to label preferentially insulin-producing cells in the pancreatic gland. In the present study, D-[3H]-mannoheptulose uptake by rat pancreatic islets or dispersed islet cells was found to represent a time-related and temperature-sensitive process inhibited by cytochalasin B. This mould metabolite also inhibited the efflux of D-[3H]-mannoheptulose from prelabelled islets. After 60 min incubation at 37 degrees C, the apparent intracellular distribution space of the tritiated heptose was close to or somewhat higher than that of D-[5-3H]glucose and close to 50% of the intracellular 3HOH space. It was further enhanced by D-glucose and a high concentration of 10 mM of D-mannoheptulose. The uptake of D-[3H]mannoheptulose was much lower however than that of D-[3H]mannoheptulose hexaacetate. As judged from the fate of D-mannoheptulose hexa[2-14C]acetate, the latter ester was efficiently hydrolyzed in the islet cells. The internalization of D-[3H]mannoheptulose (or its ester) coincided with the generation of tritiated acidic metabolites, reflecting phosphorylation of the heptose. The situation found in normal islet cells sharply differed from that found in tumoral islet cells of either the RINm5F or INS-1 line, in which the apparent distribution space of D-[3H]mannoheptulose represented only about 3 and 9%, respectively, of the intracellular 3HOH space. These results indicate that the entry of D-mannoheptulose into islet cells represents a carrier-mediated process, possibly mediated at the intervention of GLUT2 and, hence, provide further support to the possible use of a suitable D-mannoheptulose analog as a tool for the preferential labelling of insulin-producing cells in the pancreatic gland.

Animals↗

PubMed2002

Effects of D-mannoheptulose upon D-glucose metabolism in pancreatic B and non-B islet cells.

D-mannoheptulose was recently proposed to be transported into cells mainly at the intervention of GLUT2. In the present study, the heptose (10 mM) decreased the steady state content of dispersed rat pancreatic islet cells in D-[U-(14)C]glucose, and inhibited to a greater relative extent the utilization of D-[5-(3)H]glucose, the oxidation of D-[U-(14)C]-glucose and its conversion to radioactive amino acid when the dispersed islet cells were incubated at 16.7 mM rather than 2.8 mM D-glucose. A comparable situation was found in purified islet B-cells, whereas D-mannoheptulose only exerted minor to negligible effects upon the metabolism of D-glucose in non-B islet cells. This coincided with a much higher uptake of D-[(3)H]mannoheptulose by B, as distinct from non-B, islet cells. These findings indicate that the unexpectedly greater relative inhibitory action of D-mannoheptulose upon D-glucose metabolism by isolated islets (or dispersed islet cells) observed at high rather than low hexose concentration cannot be accounted for solely by differences in the relative contribution of non-B cells to total D-glucose metabolism by islets incubated at increasing concentrations of D-glucose. A comparable metabolic response to D-mannoheptulose is indeed observed in purified B cells. It could be attributable, in part at least, to D-glucose and D-mannoheptulose countertransport, resulting inter alia in a greater net uptake of the heptose by B cells exposed to a high concentration of the hexose.

Animals↗

PubMed1990

Membrane receptors on rat hepatocytes for the inner core region of bacterial lipopolysaccharides.

Bacterial lipopolysaccharides (LPS) are potent endotoxins that are thought to be involved in the pathogenesis of Gram-negative septicemia. The liver is known to be the primary organ responsible for the clearance of LPS from the systemic circulation in mammals. In this work, 125I-labeled LPS have been used in a filtration assay for the specific binding of LPS to intact rat hepatocytes. Eight S-form (smooth) LPS with complete O-specific polysaccharide chains isolated from different O-serotypes of Salmonella and Escherichia coli as well as nine R-form (rough) LPS isolated from Salmonella mutants deficient in synthesis of their core oligosaccharides were used in this study. All 125I-labeled S-form LPS and R-form LPS, except Re, show specific binding to isolated hepatocytes. The binding is saturable, is inhibited with excess unlabeled homologous or heterologous LPS but not lipid A, and is trypsin sensitive. L-Glycero-D-mannoheptose (heptose), a constituent of the inner core region of almost all LPS, is a potent inhibitor of the specific binding of 125I-labeled Rb2 LPS, whereas other monosaccharides, including 3-deoxy-D-manno-2-octulosonic acid (KDO), have weak or negligible inhibitor activity. These results strongly suggest the presence of a lectin-like receptor for the LPS inner core region (heptose-KDO region) on the plasma membrane of rat hepatocytes.

Animals↗

PubMed1975

[Obtaining purified preparations of individual Shigella newcastle K- and O-antigens by using an ultracentrifugation method].

A modified method of obtaining the purified K- and O-antigens of Sh. newcastle with the use of ultracentrifugation is described. Serologically individual K- and O-antigens were obtained and their chemical composition was studied. Polysaccharide of the K-antigen consisted of the galacturonic acid, galactose, glucose, rhamnose xylose and hexosamine; it contained no heptoses. The O-antigen contained galactose, glucose, mannose, rhamnose, heptose and hexosamine; in difference to K-antigen was equal to 150000--160000. Thus, the K- and the O-antigen differed not only in the electrophoretic and diffuse mobility and immunological specificity, but also in the chemical composition.

Antigens, Bacterial↗

PubMed1981

Phosphate localization in carbohydrates - a study on enterobacterial lipopolysaccharides.

The localization of the phosphate substituents in the core oligosaccharide of the lipopolysaccharides of Enterobacteriaceae has been reported for Salmonella minnesota and Escherichia coli B only. In these cases the localizations were done by a beta-elimination reaction in mild alkaline solution after periodate oxidation. We report now on a method generally applicable on carbohydrates. The localization of phosphate groups and the extent of substitution with phosphate residues in carbohydrates can be determined by the following reaction sequence: methylation, dephosphorylation, and reetherification (labelling) with C2H3J or C2H5J followed by derivatizing to partially methylated alditol acetates and analysis by combined gas liquid chromatography/mass spectrometry. The results presented here are obtained by application of this method to isolated core oligosaccharides of lipopolysaccharides from E. coli C23.1, E. coli C71, E. coli F2515, and P. mirabilis R4/O 28. Phosphate is localized at C-4 of the chain heptoses in the lipopolysaccharides of E. coli C and E. coli R4, and at C-7 of the branching heptose in the lipopolysaccharide of P. mirabilis R4/O 28.

Chemical Phenomena↗

PubMed1976

[Chemotypes of "Shigella flexneri" R mutants and related phage receptors. II. -- Localization of phage receptors (author's transl)].

Receptor sites for phages FP3, V, P1kcvir, H+, C21, T4, T3, T7 and 6SR have been investigated, by comparing the lytic activity of these phages on R mutants of strain F6 (F6R) and of various serotypes (FH) of Shigella flexneri with their inhibition by the lipopolysaccharides isolated from these mutants. The results suggest the following localizations for the receptor sites: phage FP3: lipid A-KDO; phage V: heptose or glucose; phage C21: heptose-glucose; phages H+, P1kcvir, T4 and T3: glucose; phage T7: glucose-galactose; phage 6SR: complete core structure.

Bacteriophages↗

PubMed1993

[Further types of core lipopolysaccharides in Proteus].

Comparative analysis of the chemical composition of 11 core oligosaccharides isolated from lipopolysaccharides of the wild (S) and phenotypically rough (R) strains Proteus mirabilis (nine) and Proteus vulgaris (two) allowed to recognize three new types Proteus core, classified as IV, V, VI. All of them contained D-galactose and D-galactosamine in addition to common core constituents: D-glucose, D-galacturonic acid, L-glycero-D-manno-heptose, KDO, EtN described for Proteus core types I, II, III (6, 7, 8). D-glucosamine was characteristic for Proteus core type VI whereas D-glycero-D-manno-heptose for types V and VI.

Oligosaccharides↗

PubMed1964

ORIGIN AND PROPERTIES OF NATURALLY OCCURRING HAPTEN FROM ESCHERICHIA COLI.

Anacker, R. L. (National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Mont.), R. A. Finkelstein, W. T. Haskins, M. Landy, K. C. Milner, E. Ribi, and P. W. Stashak. Origin and properties of naturally occurring hapten from Escherichia coli. J. Bacteriol. 88:1705-1720. 1964.-Haptens found in preparations of endotoxin and in fractions of disrupted cells, particularly one termed "native hapten," which appeared to be associated with the protoplasm of cells rather than with cell walls, have been further investigated with a view to establishing their origin and composition as well as their host-reactive properties. For this purpose, cells from a smooth strain of Escherichia coli O111:B4 were either extracted directly or disrupted and separated into cell-wall and protoplasmic fractions. Haptens were obtained by gel filtration of endotoxins, by trichloroacetic acid extraction of protoplasm, and by a mild acid hydrolysis of endotoxin. Several lines of evidence indicated that native hapten originated in the protoplasm rather than by autolysis or degradation of cell-wall endotoxin during procedures employed in disruption. In gel diffusion and quantitative precipitin tests, no hapten was identical with endotoxin, but native hapten was serologically the most complex of the haptens and precipitated the most antibody. Native and acid haptens, on a weight basis, fixed about 1% of the quantity of complement fixed by homologous endotoxin. Haptens did not stimulate the production of antibodies in mice or rabbits and did not elicit endotoxic host reactions. Chemically, native hapten differed from endotoxin and from acid hapten in that it lacked phosphorus, heptose, long-chain fatty acids, and 2-keto-3-deoxyoctonate. These substances did not appear to be determinants of antigenic specificity, but they may provide necessary bonds for assembling hapten-like units into fully antigenic and toxic macromolecules.

Animals↗

PubMed1977

Isolation of alpha-glucan and lipopolysaccharide fractions from Acetobacter xylinum.

A cellular phenol-water extract of Acetobacter xylinum NRC 17007 was fractionated on Sepharose 4 B. The fraction eluting with the void volume consisted to about 95% of glycogen-like material. The lipopolysaccharide fraction was of lower molecular weight and had the following composition (%, w/w): Mannose, 42; glucose, 7; galactose, 3.8; heptose, 2; 2-keto-3-deoxy-octonate, 1.2; glucosamine, 3.3; phosphate, 4.5; total fatty acids, 3.9. Among the fatty acids, 3-hydroxy-tetradecanoic acid was present, and 2-hydroxy-hexadecanoic acid predominated.

Carbohydrates↗

PubMed1991

Structural analysis of the heptose/hexose region of the lipopolysaccharide from Escherichia coli K-12 strain W3100.

The disaccharide L-glycero-D-manno-heptosyl-D-glucose was isolated from the lipopolysaccharide (LPS) of Escherichia coli K-12 strain W3100 after partial hydrolysis with acid, and the structure was determined by methylation analysis, n.m.r. spectroscopy, and comparison with a synthetic standard. In addition, the oligosaccharides L,D-Hep-D-Glc-D-Glc and L,D-Hep-D-Glc-D-Glc-D-Glc were isolated, and their structures were established by g.l.c.-m.s. and methylation analysis. The results indicated that L-glycero-D-manno-heptose, a characteristic constituent of the inner core region, may also occur in the outer core region which, in E. coli, is generally composed of hexoses. A revised structure of the carbohydrate backbone of the hexose/heptose region of the LPS is given.

Carbohydrate Conformation↗

PubMed1996

Structural study on a lipopolysaccharide from Coxiella burnetii strain Nine Mile in avirulent phase II.

A lipopolysaccharide isolated from Coxiella burnetti strain Nine Mile in avirulent phase II contains in the lipid A proximal region D-mannose, D-glycero-D-manno-heptose, and 3-deoxy-D- manno-oct-2-ulosonic acid (Kdo) in the molar ratio 2:2:3. The primary structure 1 of the heptasaccharide was determined by glycose analysis, methylation analysis, ESI-MS, and FABMS. [sequence: see text]

Carbohydrate Conformation↗

PubMed2001

Distribution of pyranose and furanose forms of 6-deoxyheptoses in water solution.

On the basis of 1H and 13C NMR spectroscopy studies, the proportion of pyranose and furanose forms of 6-deoxyheptoses in water solution was determined. Water solution of 6-deoxyheptoses contains all possible furanose and pyranose forms (except 6-deoxy-gluco-heptose for which only pyranose was found), although pyranose is dominant.

Carbohydrate Conformation↗

PubMed2001

Structure of a D-glycero -D-manno-heptan from the lipopolysaccharide of Helicobacter pylori.

A lipopolysaccharide (LPS) was isolated by hot phenol-water extraction from Helicobacter pylori strain D4 and found to contain no fucosylated poly-N-acetyllactosamine chain typical of most H. pylori strains studied but a homopolymer of D-glycero-D-manno-heptose (DD-Hep). The heptan attached to a core oligosaccharide was released by mild acid degradation of the LPS, and the following structure of the trisaccharide-repeating unit was established by chemical methods and 1H and 13C NMR spectroscopy: --> 2)-D-alpha-D-Hepp-(1 --> 3)-D-alpha-D-Hepp-(1 --> 3)-D-alpha-D-Hepp-(1 -->. 1H NMR spectroscopy performed on small amounts of the intact LPS revealed the presence of the same polysaccharide in LPS of H. pylori strains D2 and D5, but not strain D10.

Helicobacter pylori↗

PubMed2006

Attempts to assemble a universal NMR database without synthesis of NMR database compounds.

[structure: see text] The feasibility of assembling 3JH,H profiles from NMR data collected on relevant, but not necessarily specific, NMR database compounds representing a given stereocluster was demonstrated. By this approach, the 3JH,H profile was created for the contiguous tetraol peracetate stereocluster. The reliability and applicability of the database thus assembled were demonstrated for known peracetates derived from two heptoses.

Acetates↗