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At least 865 records · Page 48Linked to original sources
PubMed1998

[The influences of lanthanum,cerium and fluoride on the activity of glucosyltransferase(GTF) and adherence of oral cariogenic bacteria in vitro]

OBJECTIVE:Study of the influences of lanthanum,cerium and fluoride on the activity of flucosyltransferase(GTF) and adherence of oral cariogenic bacteria. METHODS: The influences of lanthanum,certium and fluoride on the acitivity of GTF and adherences of Steptococcus sobrinus 6715,Lactobacillus 4356 and Actinomycetes viscosus 19246 in vitro were investigated. RESULTS: Lanthanum and cerium can efficiently inhibit the acitivity of GTF than fluoride. CONCLUSION: The result was given a data that lanthanum and cerium could be used as a cariostatic agent in future.At the same time the inhibition of the bacterial adherence by these trace elements was also revealed.

Journal Article↗
PubMed1986

Biosynthesis of bacterial glycogen. Primary structure of Escherichia coli ADP-glucose:alpha-1,4-glucan, 4-glucosyltransferase as deduced from the nucleotide sequence of the glgA gene.

The nucleotide sequence of the glgA gene, coding for glycogen synthase (EC 2.4.1.21) was elucidated. It consists of 1431 base pairs specifying a protein of 477 amino acids. The deduced amino acid sequence was consistent with the amino acid analysis obtained with the pure protein as well as with the molecular weight as determined from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The deduced amino acid sequence was also consistent with the amino-terminal acid sequence and amino acid sequence analysis of various peptides obtained from CNBr degradation of purified glycogen synthase.

Amino Acid Sequence↗
PubMed1985

[Subcellular localization of glycogen-UDP-glucosyltransferase in the hepatocytes of intact and fasting rats].

Electron microscope cytochemical techniques by Takeuchi et al. were used to study the localization of glycogen-UDP-glucosyl-transferase (GUDPG) in hepatocytes of intact and fasting rats. Glycogen was found in the cytoplasm, nuclei, mitochondria, microbodies and lysosomes of the hepatocytes of intact and fasting animals after special cytochemical procedures for determination of GUDPG.

Animals↗
PubMed1995

Evolutionary link between glycogen phosphorylase and a DNA modifying enzyme.

We report here an unexpected similarity in three-dimensional structure between glucosyltransferases involved in very different biochemical pathways, with interesting evolutionary and functional implications. One is the DNA modifying enzyme beta-glucosyltransferase from bacteriophage T4, alias UDP-glucose:5-hydroxymethyl-cytosine beta-glucosyltransferase. The other is the metabolic enzyme glycogen phosphorylase, alias 1.4-alpha-D-glucan:orthophosphate alpha-glucosyltransferase. Structural alignment revealed that the entire structure of beta-glucosyltransferase is topographically equivalent to the catalytic core of the much larger glycogen phosphorylase. The match includes two domains in similar relative orientation and connecting helices, with a positional root-mean-square deviation of only 3.4 A for 256 C alpha atoms. An interdomain rotation seen in the R- to T-state transition of glycogen phosphorylase is similar to that observed in beta-glucosyltransferase on substrate binding. Although not a single functional residue is identical, there are striking similarities in the spatial arrangement and in the chemical nature of the substrates. The functional analogies are (beta-glucosyltransferase-glycogen phosphorylase): ribose ring of UDP-pyridoxal ring of pyridoxal phosphate co-enzyme; phosphates of UDP-phosphate of co-enzyme and reactive orthophosphate; glucose unit transferred to DNA-terminal glucose unit extracted from glycogen. We anticipate the discovery of additional structurally conserved members of the emerging glucosyltransferase superfamily derived from a common ancient evolutionary ancestor of the two enzymes.

Amino Acid Sequence↗
PubMed1986

Topology of glucosylceramide synthesis in Golgi membranes from porcine submaxillary glands.

The topology of ceramide glucosyltransferase and de novo synthesized glucosylceramide was studied in sealed and 'right-side-out' vesicles of porcine submaxillary glands derived from Golgi apparatus. Pronase treatment which did not cause any breakdown of the luminal glycoprotein galactosyltransferase activity, inhibited the ceramide glucosyltransferase to more than 50% at a ratio proteinase to Golgi protein 1:100. Trypsin at the same concentration, while producing no inactivation of luminal galactosyltransferase, caused a complete loss of ceramide glucosyltransferase activity. The membrane-impermeable compound, DIDS, which did not cause any inhibition of the galactosyltransferase, inhibited the ceramide glucosyltransferase (70% reduction at 80 microM DIDS). Thus, the enzyme ceramide glucosyltransferase is accessible from the cytoplasmic side of the Golgi vesicles. The orientation of the newly synthesized glucosylceramide is studied by the ability of the enzyme glucosylceramidase to hydrolyse this compound both on intact and on disrupted vesicles. The same percentage (respectively, 36 and 30%) of hydrolysis was obtained during an incubation of 3 h, showing that glucosylceramide is not at all protected from external hydrolysis. Pronase-treated vesicles revealed an increase in glucosylceramidase hydrolysis (up to 45%), which indicates that glucosylceramide that glucosylceramide may be cryptic. All these results indicate that the ceramide glucosyltransferase, as well as related glucosylceramide, are cytoplasmically oriented in Golgi vesicles from porcine submaxillary glands.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1982

(1,3)-beta-D-Glucan synthase from budding and filamentous cultures of the dimorphic fungus Candida albicans.

UDPglucose:(1,3)-beta-D-glucan 3-beta-D-glucosyltransferase (EC 2.4.1.34) was obtained as a particulate fraction from cell-free extracts prepared after mechanical breakage of cells of a strain of the dimorphic fungus Candida albicans. The properties of this glucosyltransferase were investigated. Budding and filamentous cultures of C. albicans were grown after dilution of a stationary phase inoculum of yeast cells into fresh medium at 30 degrees C and 40 degrees C respectively and the specific activities of (1,3)-beta-D-glucan synthase, obtained from budding and filamentous cultures harvested during the first 3 h of their growth, were compared. 1. UDPglucose was the only glucosyl donor in the reaction (assayed by following the incorporation of radioactivity from UDP[14C]glucose into polymer) and the radioactive product was exclusively beta-(1,3)-glucan. 2. Glycogen synthase activity was not detected. 3. (1,3)-beta-D-Glucan synthase activity was enhanced by ATP and GTP. 4. A threefold increase in the specific activity of the glucosyltransferase was obtained when cell breakage, and subsequent steps in the preparation of the enzyme, were carried out in the presence of 25 microM GTP. A Km value for UDPglucose of 1.5-1.9 mM was obtained for the glucosyltransferase prepared in the presence or absence of GTP. 5. The glucosyltransferase reaction was not affected by ADPglucose, CDPglucose, GDPglucose or glucose 6-phosphate, but was competitively inhibited by TDPglucose. GDPglucose was not a glucosyl donor under the present conditions. 6. There was no evidence that the product was N-glycosidically linked to protein, since the reaction was neither enhanced in the presence of UDP-N-acetylglucosamine, nor inhibited by tunicamycin. 7. The specific activity of the glucosyltransferase from 3-h-old filamentous cultures was about 1.5-times higher than that from 3-h-old budding cultures. 8. The specific activities of (1,3)-beta-D-glucan synthase prepared from budding and filamentous cultures of C. albicans during their first 90 min of growth were similar.

Adenosine Triphosphate↗
PubMed1976

[Studies on the initiation of glycogen metabolism in Escherichia coli (author's transl)].

Glycogen biosynthesis was studied in Escherichia coli. An enzyme complex composed of UDP-glucose; protein glucosyltransferase, ADP-glucose: protein glucosyltransferase and ADP-glucose: alpha-1,4 glucan alpha-4-glucosyltransferase was found. Further results revealed that while glycogen concentration remained unchanged, the specific activity of the glucosyltransferase complex increased during the growth phase of the culture. The detergents Lubrol and Brij provoked a decrease of 80% and 20% in the glucose transfer to protein from ADP-glucose and UDP-glucose, respectively. These detergents did not inhibit the glucose incorporation into glycogen by ADP-glucose: alpha-1,4-glucosyltransferase. We postulated that the biosynthesis of glycogen in Escherichia coli could be initiated by two different enzymes which catalyze the transfer of glucose from UDP-glucose or ADP-glucose to an acceptor protien. In a second step, the glucan protein formed is used as primer by the ADP-glucose: alpha-1,4 glucan alpha-1-glucosyltransferase for glycogen formation.

Detergents↗
PubMed1977

Properties of a variant of Streptococcus mutans altered in its ability to interact with glucans.

After continuous subculture of Streptococcus mutans GS-5, the resultant organism, GS-5var, was found to be altered in its ability to undergo dextran- and sucrose-induced cell agglutination and to adhere to smooth surfaces in the presence of sucrose. Both GS-5 and GS-5var cells possessed the serotype c polysaccharide antigen, displayed similar growth kinetics, appeared to have similar metabolic and biosynthetic capabilities, and produced similar amounts of cell-associated and extracellular glucosyltransferase activity in chemically defined medium. GS-5 cells which had bound exogenous glucosyltransferase enzymes from either cell type were able to undergo sucrose-dependent adherence to smooth surfaces, whereas GS-5var cells which had bound comparable levels of glucosyltransferase activity were unable to adhere. In contrast to GS-5var cells, GS-5 cells were also able to adhere to preformed glucan deposits. In addition, [(14)C]glucan binding studies demonstrated that GS-5 cells were able to bind fourfold-greater levels of [(14)C]glucan relative to GS-5var cells having similar cell-associated glucosyltransferase activity. Further study of GS-5 cells also suggested the existence of a glucan binding site, distinct from the cell-associated glucosyltransferase activity, which is important in dextran-induced agglutination and sucrose-dependent adherence to smooth surfaces. These results are discussed in terms of the alteration of the GS-5var cells and their possible relationship to the putative receptors for glucosyltransferase enzymes and glucans on the cell surface of S. mutans.

Agglutination Tests↗
PubMed1997

Characterization of Leuconostoc mesenteroides NRRL B-512F dextransucrase (DSRS) and identification of amino-acid residues playing a key role in enzyme activity.

Dextransucrase (DSRS) from Leuconostoc mesenteroides NRRL B-512F is a glucosyltransferase that catalyzes the synthesis of soluble dextran from sucrose or oligosaccharides when acceptor molecules, like maltose, are present. The L. mesenteroides NRRL B-512F dextransucrase-encoding gene (dsrS) was amplified by the polymerase chain reaction and cloned in an overexpression plasmid. The characteristics of DSRS were found to be similar to the characteristics of the extracellular dextransucrase produced by L. mesenteroides NRRL B-512F. The enzyme also exhibited a high homology with other glucosyltransferases. In order to identify critical amino acid residues, the DSRS sequence was aligned with glucosyltransferase sequences and four amino acid residues were selected for site-directed mutagenesis experiments: aspartic acid 511, aspartic acid 513, aspartic acid 551 and histidine 661. Asp-511, Asp-513 and Asp-551 were independently replaced with asparagine and His-661 with arginine. Mutation at Asp-511 and Asp-551 completely suppressed dextran and oligosaccharide synthesis activities, showing that at least two carboxyl groups (Asp-511 and Asp-551) are essential for the catalysis process. However, glucan-binding properties were retained, showing that DSRS has a two-domain structure like other glucosyltransferases. Mutations at Asp-513 and His-661 resulted in greatly reduced dextransucrase activity. According to amino acid sequence alignments of glucosyltransferases, alpha-amylases or cyclodextrin glucanotransferases, His-661 may have a hydrogen-bonding function.

Amino Acid Sequence↗
PubMed2006

Isomaltulose production using free cells: optimisation of a culture medium containing agricultural wastes and conversion in repeated-batch processes.

The enzyme glucosyltransferase is an industrially important enzyme since it produces non-cariogenic isomaltulose (6-O-alpha-D-glucopyronosyl-1-6-D-fructofuranose) from sucrose by intramolecular transglucosylation. The experimental designs and response surface methodology (RSM) were applied for the optimisation of the nutrient concentrations in the culture medium for the production of glucosyltransferase by Erwinia sp. D12 in shaken flasks at 200 rpm and 30 degrees C. A statistical analysis of the results showed that, in the range studied, the factors had a significant effect (P < 0.05) on glucosyltransferase production and the highest enzyme activity (10.84 U/ml) was observed in culture medium containing sugar cane molasses (150 g l(-1)), corn steep liquor (20 g l(-1)), yeast extract Prodex Lac SD (15 g l(-1)) and K2HPO4 (0.5 g l(-1)) after 8 h at 30 degrees C. The production of cell biomass by the strain of Erwinia sp. D12 was carried out in a 6.6-l fermenter with a mixing rate of 200 rpm and an aeration rate of 1 vvm. Fermentation time, cellular growth, medium pH and glucosyltransferase production were observed. The greatest glucosyltransferase activity was 22.49 U/ml, obtained after 8 h of fermentation. The isomaltulose production from sucrose was performed using free Erwinia sp. D12 cells in a batch process using an orbital shaker. The influence of the parameters sucrose concentration, temperature, pH, and cell concentration on the conversion of sucrose into isomaltulose was studied. The free cells showed a high conversion rate of sucrose into isomaltulose using batch fermentation, obtaining an isomaltulose yield of 72.11% from sucrose solution 35% at 35 degrees C.

Biomass↗
PubMed1977

Intracellular enzymes of collagen biosynthesis in human platelets.

Activities of four intracellular enzymes of collagen biosynthesis--prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase, and collagen glucosyltransferase--were demonstrated in human platelets, and the presence of prolyl hydroxylase protein was further demonstrated by direct radioimmunoassay. The ratio of the specific activities of the four enzymes in the four enzymes in the human platelet extract to those in human adult skin extract varied from about 0.1 to 1, the lowest relative activity being found with prolyl hydroxylase and the highest with collagen glucosyltransferase. Only a very small amount of prolyl hydroxylase protein, probably 1%, was in the form of the active enzyme tetramer. The collagen glucosyltransferase from human platelets readily glucosylated galactosylhydroxylysine in denatured collagen, but did not glucosylate native collagen. Also, native collagen did not act as an inhibitor of the glucosylation reaction. Therefore, platelet collagen glucosyltransferase cannot form either an enzyme--substrate complex or an enzyme--inhibitor complex with native collagen. The results thus argue against the theory which maintains that platelet collagen glucosyltransferase is involved in collagen--platelet adhesion.

Blood Platelets↗
PubMed2004

Alteration of sugar donor specificities of plant glycosyltransferases by a single point mutation.

In comparison with the amino acid sequences of seven species of glucosyltransferases and six species of galactosyltransferases, glutamine and histidine are highly conserved as the last amino acid residue of a glycosyltransferase-specific conserved region (UDPGT) in glucosyltransferases and galactosyltransferases, respectively. Consequently, the sugar donor specificities of glycosyltransferases are successfully altered by a single amino acid point mutation. UDP-galactose:anthocyanin galactosyltransferase (ACGaT), isolated from Aralia cordata, acquired glucosyltransferase activity in addition to the inherent galactosyltransferase activity by replacing histidine with glutamine. In contrast, UDP-glucose:flavonoid glucosyltransferase (UBGT), isolated from Scutellaria baicalensis, did not acquire galactosyltransferase activity by replacing glutamine with histidine, and exhibited a remarkable decrease in glucosyltransferase activity.

Amino Acid Sequence↗
PubMed1970

Enzymes of carbohydrate metabolism in the developing endosperm of maize.

A number of enzymes presumably implicated in starch synthesis were assayed at various stages of endosperm development ranging from 8 days to 28 days after pollination. Activity for invertase, hexokinase, the glucose phosphate isomerases, the phosphoglucomutases, phosphorylase I, uridine diphosphate glucose pyrophosphorylase, and the starch granule-bound nucleoside diphosphate glucose-starch glucosyltransferase was present at the earliest stage of development (8 days) studied. Activity was detectable for phosphorylase III, the soluble adenosine diphosphate glucose-starch glucosyltransferase, adenosine diphosphate glucose pyrophosphorylase, and sucrose-uridine diphosphate glucosyltransferase at 12 days. For phosphorylase II and cytidine diphosphate glucose pyrophosphorylase, activity was first detectable at the 14- and 16-day stages, respectively. Rapid increases in starch content are observed prior to detectable activity for adenosine diphosphate glucose pyrophosphorylase, the soluble adenosine diphosphate glucose-starch glucosyltransferase and phosphorylases II and III. For all enzymes, except invertase, activity per endosperm rises to a peak at 22 or 28 days. Greatest activity for invertase is found at 12 days with a steady decline thereafter. The pattern of invertase activity in comparison with that of sucrose-uridine diphosphate glucosyltransferase supports previous suggestions, that the latter plays a key role in the conversion of sucrose to starch. In addition to phosphorylases I, II, and III, multiple forms of glucosephosphate isomerase and phosphoglucomutase were detected.

Journal Article↗