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PubMed1987

Studies on the physical state of water in living cells and model systems. VII. Exclusion of sugars and sugar alcohols from the water in sulfonate ion exchange resins: the "size rule".

The equilibrium distribution of D-arabinose, glycerol, D-ribose, sorbitol, sucrose or inulin in the water of sulfonate ion exchange resins (containing as counterions to the sulfonate anions, H+, Li+, Na+, K+, Rb+, Cs+, NH4+, tetraethylammonium or tetra-n-butyl-ammonium) was studied, usually at one temperature (25 degrees C) but sometimes at two (25 degrees C, 0 degrees C). The apparent equilibrium distribution (p-value) changes with the nature of the counterion, temperature and the molecular weights of the sugar, sugar alcohols, and derivative in question. Linear correlation coefficients between the molecular weights of the solutes and their respective p-values in the range of -0.92 to -0.93 were obtained when the resins were in the Li+, Na+, K+, or Rb+ form.

Anion Exchange Resins↗
PubMed2000

Surface Activity and Critical Aggregation Concentration of Pure Sugar Esters with Different Sugar Headgroups.

We have studied the surface properties of a series of enzymatically synthesized sugar monoesters of xylose, galactose, sucrose, and lactose with different hydrophobic chain lengths (C12-C16) and purified, chemically synthesized sucrose esters that, unlike the enzymatically synthesized samples, contain a mixture of isomers. Data obtained have been compared with those for dodecanoic glucoside and maltoside acetals, and also a commercial sucrose myristate. Nearly all of the sugar esters studied brought about a significant reduction of the surface tension of water (to 31.0-43.0 mN m(-1)). A reduction in the critical aggregation concentration (CAC) of the surfactants with increasing carbon chain length was observed. Surfactants with more hydrophilic headgroups exhibited higher CAC, though this trend was moderated by the alkyl chain length. Comparing the chemically synthesized sucrose esters with their enzymatically synthesized equivalents revealed only minor differences in the CAC and the surfactant efficiency, indicating that the exact point of esterification might not be critical for the surfactant's properties. The presence of 0.1 M NaCl, KCl, or CaCl(2) did not significantly alter the surface behavior of the chemically synthesized esters, indicating the absence of surface-active species with charged headgroups. Copyright 2000 Academic Press.

Journal Article↗
PubMed1985

Antimicrobial effect of sugar osazones and anhydro sugars.

The antimicrobial effect of 14 sugar osazones and anhydro sugars was studied with model strains of Micrococcus luteus, Bacillus licheniformis, Escherichia coli and strains Staphylococcus aureus and Pseudomonas aeruginosa isolated from clinical material. The relationship between the structure of these compounds, their solubility in water and 1-octanol and antimicrobial effect was investigated.

Bacillus↗
PubMed1985

A specific method for the determination of soluble sugars in plant extracts using enzymatic analysis and its application to the sugar content of developing pear fruit buds.

A simple manual method for the routine analysis of glucose, fructose, mannose, galactose, and sucrose in plant material is described. The technique is demonstrated using various seeds known to form part of the diet of the bullfinch (Pyrrhula pyrrhula L.), a pest of commercial orchards in southeast England. The method involves the overnight extraction of the sugars with 62.5% aqueous methanol, followed by the conversion of the individual sugars to gluconate 6-phosphate (or, in the case of galactose, to galactono-gamma-lactone) by specific enzymes, and their determination spectrophotometrically.

Carbohydrates↗
PubMed1994

The sugar-combining area of the galactose-specific toxic lectin of mistletoe extends beyond the terminal sugar residue: comparison with a homologous toxic lectin, ricin.

Viscumin (the major lectin of mistletoe extract), also known as ML-1, and ricin (RCA II) belong to a group of heterodimeric toxic lectins composed of an A chain, which inhibits protein synthesis, and a B chain, which mediates entry into the cell in a galactose-specific manner. Although most of the binding force for the association of viscumin with galactose-containing ligands is generated by the nonreducing terminal galactose residue, a particular hydroxyl group on the penultimate sugar also appears to participate in the binding, suggesting that viscumin has an extended combining site. In this paper, we give further examples of affinity enhancement by the hydroxyl group situated on the penultimate sugar next to the glycosidic linkage of the terminal galactose. The structure with highest affinity for viscumin thus far discovered is beta-D-Gal-(1-->2)-beta-D-Gal. In contrast to viscumin, ricin does not have this extended binding area, as none of the disaccharides tested exhibited significant affinity enhancement.

Carbohydrate Conformation↗
PubMed2005

Identification and characterization of human Golgi nucleotide sugar transporter SLC35D2, a novel member of the SLC35 nucleotide sugar transporter family.

We report the molecular cloning of SLC35D2, a novel member of the SLC35 nucleotide sugar transporter family. The gene SLC35D2 maps to chromosome 9q22.33. SLC35D2 cDNA codes for a hydrophobic protein consisting of 337 amino acid residues with 10 putative transmembrane helices. Northern blot analysis revealed the SLC35D2 mRNA as a single major band corresponding to 2.0 kb in length. SLC35D2 was localized in the Golgi membrane and exhibited around 50% similarity with three nucleotide sugar transporters: human SLC35D1 (UDP-glucuronic acid/UDP-N-acetylgalactosamine transporter), fruitfly fringe connection (frc) transporter, and nematode SQV-7 transporter, the latter two being involved in developmental and organogenetic processes. Heterologous expression of SLC35D2 protein in yeast indicated that UDP-N-acetylglucosamine is a candidate for the substrate(s) of the transporter. The sequence similarity, subcellular localization, and transporting substrate suggest that SLC35D2 is a good candidate for the ortholog of frc transporter, which is involved in the Notch signaling system by providing the fringe N-acetylglucosaminyltransferase with the substrate. We also describe the identification and categorization of the human SLC35 gene family.

Amino Acid Sequence↗
PubMed2000

Rare sugars and sugar-based synthons by chemo-enzymatic synthesis.

The unique catalytic potential of the fungal enzyme pyranose oxidase was demonstrated by preparative conversions of a variety of carbohydrates, and by extensive chemical characterization of the reaction products with NMR spectroscopy. The studies revealed that POx not only oxidizes most substrates very efficiently but also that POx possesses a glycosyl-transfer potential, producing disaccharides from beta-glycosides of higher alcohols. Although most substrates are oxidized by POx at the C-2 position, several substrates are converted into the 3-keto-derivatives. On the basis of these products, strategies are developed for the convenient production of sugar-derived synthons, rare sugars and fine chemicals by combining biotechnical and chemical methods.

Journal Article↗
PubMed2001

Ion-pair RP-HPLC determination of sugars, amino sugars, and uronic acids after derivatization with p-aminobenzoic acid.

A new, selective, and sensitive ion-pair RP-HPLC method for the simultaneous determination of three classes of natural organic compounds, i.e., carbohydrates, amino sugars, and uronic acids, in environmental samples is presented. p-Aminobenzoic acid is used for precolumn derivatization of the analytes, enabling fluorescence (lambda(ex) 313 nm, lambda(em) 358 nm) or photometric detection (303 nm). The dependence of the derivatization yield on the reaction conditions is examined. Derivatives of lactose, galactose, glucose, mannose, xylose, arabinose, galacturonic acid, glucuronic acid, N-acetylglucosamine, and glycerinealdehyde were separated on a RP-C18 column with hydrophilic end capping within 35 min, applying TBAHSO4 as the ion-pair reagent. The concentration detection limits range between 20 and 30 microg L(-1) ((1-2) x 10(-7) M) for fluorescence detection and between 30 and 75 microg L(-1) for UV detection. A good linearity is achieved in the concentration range from 50 microg L(-1) to 100 mg L(-1) (r2 > 0.99). The described method has been applied for the determination of mono-/disaccharides, uronic acids, and amino sugars in soil solutions and in landfill leachates.

Journal Article↗
PubMed1993

pH changes in plaque after eating snacks and meals, and their modification by chewing sugared- or sugar-free gum.

Previous studies have suggested that if either sugar-free or sucrose-containing chewing gum is chewed after acidogenic meals or snacks, the plaque pH response to the latter is reduced and the potential for remineralisation of experimental white spot caries lesions is enhanced. This study has compared the effects of both gums on plaque pH (measured by the sampling technique) in 10 subjects who chewed the gums after standard acidogenic challenges (sucrose rinse, cupcake, and fried chicken dinner). The results showed that while both gums can significantly reduce the acid response, sugar-free gum appears more effective.

Adult↗
PubMed1997

Sugar induced cell death in yeast is dependent on the rate of sugar phosphorylation as determined by Arabidopsis thaliana hexokinase.

Sugars like glucose and fructose induce death of yeast cells within a few hours, in the absence of additional nutrients to support growth, while cells incubated in water remain viable for weeks. This sugar-induced cell death (SICD) by glucose and fructose required glucose or fructose phosphorylation since yeast cells deficient in hexose phosphorylation did not die. However, when hexose phosphorylation is restored by complementation with Arabidopsis thaliana hexokinase, the cells died. The affinity of A. thaliana hexokinase is about 400 times higher for glucose than for fructose, therefore, A. thaliana hexokinase was further utilized to study the role of hexose phosphorylation in SICD. The rate of SICD of hexokinase-deficient yeast cells expressing A. thaliana hexokinase was significantly slower in fructose than in glucose, indicating that SICD is determined by the rate of hexose phosphorylation. The significance of hexose phosphorylation and its role in SICD is discussed.

Journal Article↗
PubMed1983

Sugar transport in rat liver lysosomes. Direct demonstration by using labelled sugars.

Purified rat liver lysosomes ('tritosomes') were prepared from rats injected with Triton WR-1339. 2. The water space of tritosomes, measured by using [3H]water and [14C]sucrose, was 2.15 +/- 0.72 microliter/mg of protein (mean +/- S.E.M., n = 12). 3. Tritosomes, when compared with a crude preparation of normal lysosomes by an indirect method of study, showed sugar specificity but decreased stereospecificity of sugar uptake. 4. At 125 mM the relative rates of net uptake of D-[14C]ribose, D-[14C]- or D-[3H]glucose and 2-deoxy-D-[3H]glucose were the same as that inferred from the indirect study. 5. The entry of D-[3H]glucose into tritosomes showed concentration-dependence suggestive of saturation, with a Km of 48 +/- 18 mM (4). 6. D- and L-glucose, D-ribose, 2-deoxy-D-glucose and D-mannose competed with D-[14C]glucose or D-[14C]ribose for uptake. 7. Cytochalasin B inhibited D-[3H]glucose uptake. 8. Uptake of 1 mM-L-[14C]glucose was slower than for 1 mM-D-[14C]glucose. 9. It is concluded that a facilitated-diffusion transport system is present in purified rat liver lysosomes.

Acetylglucosaminidase↗
PubMed2006

Detection of weak sugar binding activity of VIP36 using VIP36-streptavidin complex and membrane-based sugar chains.

High mannose-type glycan-lectin interactions play important roles especially in quality control of glycoproteins. VIP36 is a receptor with homology to plant leguminous lectins in its luminal region. The luminal region of VIP36 with a C-terminal biotinylation-tag (sVIP36) was expressed in Escherichia coli and oligomerized with R-phycoerythrin (PE)-labelled streptavidin. Flow cytometric analysis revealed that PE-labelled sVIP36-SA complex (sVIP36-SA) bound to deoxymannojirimycin (DMJ)- and kifunensine (KIF)-treated HeLaS3 cells. The binding of sVIP36-SA to HeLaS3 cells treated with DMJ or KIF was abolished by endo-beta-N-acetylglucosaminidase H treatment of the cells. Furthermore, the binding of sVIP36-SA to the cells was inhibited by high mannose-type glycans especially Man(7-9) GlcNAc(2), indicating that the binding of sVIP36-SA to cell surfaces was mediated by high mannose-type glycans. Although VIP36 has the lower affinity for ligands than typical homologous plant lectins, we were able to monitor the sugar-binding activity of VIP36 using less than 100 ng of the sVIP36-SA. This method is highly sensitive and suitable for detecting interactions between lectins and sugar chains of low affinity.

1-Deoxynojirimycin↗
PubMed1996

NMR of all-carbon-13 sugars: an application in development of an analytical method for a novel natural sugar, 1,5-anhydrofructose.

Of the all-carbon-13 compounds, glucose is one of the most easily accessible, and therefore we applied 13C-NMR technique to the metabolic study of glucose-related compounds, 1,5-anhydro-D-glucitol and 1,5-anhydro-D-fructose (AF). Applying an INADEQUATE method to the substitutes of these novel sugars fully labeled with carbon-13, we could trace out the entire carbon skeleton with high sensitivity and confirm the chemical structures of these sugars. The method also provided a much easier way to optimize the enzymatic oxidation for AF preparation: we selectively and continuously monitored the quantities, as well as their structures in aqueous solution, of the substrate and products in a noninvasive manner. Similarly relying upon information from the 13C-NMR, we developed a valuable derivatization method of AF for its GC-MS application, which was so sensitive that we were able to demonstrate the natural occurrence of AF in rat liver.

Animals↗
PubMed1987

In Vitro Sugar Transport in Zea mays L. Kernels : II. Characteristics of Sugar Absorption and Metabolism by Isolated Developing Embryos.

In vitro sugar transport into developing isolated maize embryos was studied. Embryo fresh and dry weight increased concomitantly with endogenous sucrose concentration and glucose uptake throughout development. However, endogenous glucose and fructose concentration and sucrose uptake remained constant. The uptake kinetics of radiolabeled sucrose, glucose, and fructose showed a biphasic dependence on exogenous substrate concentration. Hexose uptake was four to six times greater than sucrose uptake throughout development. Carbonylcyanide-m-chlorophenylhydrazone and dinitrophenol inhibited sucrose and glucose uptake significantly, but 3-O-methyl glucose uptake was less affected. The uptake of 1 millimolar sucrose was strongly pH dependent while glucose was not. Glucose and fructose were readily converted to sucrose and insoluble products soon after absorption into the embryo. Thus, sucrose accumulated, while glucose pools remained low. Based on the findings of this and other studies a model for sugar transport in the developing maize kernel is presented.

Journal Article↗
PubMed1989

Leaf Phosphate Status, Photosynthesis and Carbon Partitioning in Sugar Beet: II. Diurnal Changes in Sugar Phosphates, Adenylates, and Nicotinamide Nucleotides.

Sugar Beets (Beta vulgaris L. cv F58-554H1) were cultured hydroponically in growth chambers. Leaf orthophosphate (Pi) levels were varied nutritionally. The effect of decreased leaf phosphate (low-P) status was determined on the diurnal changes in the pool sizes of leaf ribulose 1,5-bisphosphate (RuBP), 3-phosphoglycerate (PGA), triose phosphate, fructose 1,6-bisphosphate, fructose-6-phosphate, glucose-6-phosphate, adenylates, nicotinamide nucleotides, and Pi. Except for triose phosphate, low-P treatment caused a marked reduction in the levels of leaf sugar phosphates (on a leaf area basis) throughout the diurnal cycle. Low-P treatment decreased the average leaf RuBP levels by 60 to 69% of control values during the light period. Low-P increased NADPH levels and NADPH/NADP(+) ratio but decreased ATP; the ATP/ADP ratio was unaffected. Low P treatment caused a marked reduction in RuBP regeneration (RuBP levels were half the RuBP carboxylase binding site concentration) but did not depress PGA reduction to triose phosphate. These results indicate that photosynthesis in low-P leaves was limited by RuBP regeneration and that RuBP formation in low-P leaves was not limited by the supply of ATP and NADPH. We suggest that RuBP regeneration was limited by the supply of fixed carbon, an increased proportion of which was diverted to starch synthesis.

Journal Article↗