SEARCH · PubMed Health

Results for “GLUCOSYLTRANSFERASES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources

PubMed2003

Evidence for essential histidine and dicarboxylic amino-acid residues in the active site of UDP-glucose : solasodine glucosyltransferase from eggplant leaves.

Effects of several chemical probes selectively modifying various amino-acid residues on the activity of UDP-glucose : solasodine glucosyltransferase from eggplant leaves was studied. It was shown that diethylpyrocarbonate (DEPC), a specific modifier of histidine residues, was strongly inhibitory. However, in the presence of excessive amounts of the enzyme substrates, i.e. either UDP-glucose or solasodine, the inhibitory effect of DEPC was much weaker indicating that histidine (or histidines) are present in the active site of the enzyme. Our results suggest also that unmodified residues of glutamic (or aspartic) acid, lysine, cysteine, tyrosine and tryptophan are necessary for full activity of the enzyme. Reagents modifying serine and arginine residues have no effect on the enzyme activity.

Amino Acids, Dicarboxylic↗

PubMed2003

[The study of peptide vaccine HDS from Streptococcus mutans glucosyltransferase].

OBJECTIVE: To investigate the antigenicity of the peptide vaccine HDS from Streptococcus mutans glucosyltransferase and its ability to induce protective immune responses in an experimental rat model of dental caries. METHODS: Artificial antigen HDS-KLH, peptide HDS, glycosyltransferase were injected to immunize rats. Measurement of the specific anti-HDS, GTF IgG or IgA concentration in saliva and serum were undertaken by ELISA among the experimental groups. Gnotobiotic rat model was developed when challenged S. mutans and a caries promoting diet. The jaws of the rats were selected and dyed. The Keyes caries score for each jaw were counted. RESULTS: The level of serum and salivary specific anti-HDS IgG and IgA in the group immunized by HDS-KLH was significantly higher than that in control group (P < 0.05). The Keyes caries score of GTF, HDS and HDS-KLH immunized group were significantly lower than that of control group, especially lower in smooth tooth surface. CONCLUSION: Artificial antigen HDS-KLH could induce immune response. As a peptide vaccine, HDS-KLH could reduce the caries incidence in experimental rat model.

Animals↗

PubMed1992

Application of 5-azido-UDP-glucose and 5-azido-UDP-glucuronic acid photoaffinity probes for the determination of the active site orientation of microsomal UDP-glucosyltransferases and UDP-glucuronosyltransferases.

A new approach to determining the active site orientation of microsomal glycosyltransferases is presented which utilizes the photoaffinity analogs [32P]5-Azido-UDP-glucose ([32P]5N3UDP-Glc) and [32P]5-Azido-UDP-glucuronic acid ([32P]5N3UDP-GlcA). It was previously shown that both photoprobes could be used to photolabel UDP-glucose:dolichol phosphate glucosyltransferase (Glc-P-Dol synthase), as well as the family of UDP-glucuronosyltransferases in rat liver microsomes. The effects of detergents, proteases, and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) on the photolabeling of these enzymes were examined in intact rat liver microsomes. Photolabeling of Glc-P-Dol synthase by either photoprobe was the same in intact or disrupted vesicles, was susceptible to trypsin digestion, and was inhibited by the nonpenetrating inhibitor DIDS. Photolabeling of the UDP-glucuronosyltransferases by [32P]5N3UDP-GlcA was stimulated 1.3-fold in disrupted vesicles as compared to intact vesicles, whereas photolabeling of these enzymes by [32P]5N3UDP-Glc showed a 14-fold increase when vesicles were disrupted. Photolabeled UDP-glucuronosyltransferases were only susceptible to trypsin digestion in disrupted vesicles, and this was further verified by Western blot analyses. The results indicate a cytoplasmic orientation for access of UDP-sugars to Glc-P-Dol synthase and a lumenal orientation of most UDP-glucuronosyltransferases.

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

PubMed2004

Glucosyltransferase: the gene arrangement and enzyme function.

Glucosyltransferases were isolated and characterised from many plant sources. The enzymes show middle amino acid similarity and broad substrate specificity. The promoter of the potato 5-UGT gene reveals strong environmental induction. The activation of the gene expression by UV radiation, ABA and cold treatments was detected. Overexpression of 5-UGT resulted in the accumulation of the diglucoside derivative of petunidin in transgenic tubers; the latter is most probably the reason for plant resistance to pathogen infection. Overexpressing plants produced more tubers, and the overall yield was higher when compared to nontransformants.

Cold Temperature↗

PubMed2005

Functional characterization of the gene encoding UDP-glucose: tetrahydrobiopterin alpha-glucosyltransferase in Synechococcus sp. PCC 7942.

In this study, we attempted to characterize the Synechococcus sp. PCC 7942 mutant resultant from a disruption in the gene encoding UDP-glucose: tetrahydrobiopterin alpha-glucosyltransferase (BGluT). 2D-PAGE followed by MALDI-TOF mass spectrometry revealed that phycocyanin rod linker protein 33K was one of the proteins expressed at lower level in the BGluT mutant. BGluT mutant cells were also determined to be more sensitive to high light stress. This is because photosynthetic O2 exchange rates were significantly decreased, due to the reduced number of functional PSIs relative to the wild type cells. These results suggested that, in Synechococcus sp. PCC 7942, BH4-glucoside might be involved in photosynthetic photoprotection.

Bacterial Proteins↗

PubMed1991

Potential regulation of N-glycosylation precursor through oligosaccharide-lipid hydrolase action and glucosyltransferase-glucosidase shuttle.

The potential role of degradative mechanisms in controlling the level of the dolichyl pyrophosphate-linked Glc3Man9GlcNAc2 required for protein N-glycosylation has been explored in thyroid slices and endoplasmic reticulum (ER) vesicles, focusing on cleavage of the oligosaccharide from its lipid attachment and on the enzymatic removal of peripheral monosaccharide residues. Vesicle incubations demonstrated a substantial release of free Glc3Man9GlcNAc2 (at 30 min approximately 35% of that transferred to protein) which was inhibited in the presence of exogenous peptide acceptor and was sensitive to disruption of membrane integrity by detergent. In thyroid slices glucosylated oligosaccharides terminating in the di-N-acetylchitobiose sequence were also noted and these continued to be formed even during inhibition by puromycin of both protein synthesis and the attendant N-glycosylation. These observations indicated that the oligosaccharide originated from the lipid donor and suggested, together with previously reported similarities in substrate specificity and cofactor requirements, that the oligosaccharyltransferase can carry out in vivo both the hydrolytic and transfer functions. In addition to the release of the intact Glc3Man9GlcNAc2, we also obtained evidence that the lipid-linked oligosaccharide can be modified by the in vivo action of ER glycosidases. Since radiolabeling of the oligosaccharide-lipid in thyroid slices indicated a preferential turnover of the glucose residues, the possible existence of a glucosyltransferase-glucosidase shuttle was explored with the use of castanospermine. In the presence of this glucosidase inhibitor, the formation of under-glucosylated and nonglucosylated oligosaccharides was not observed, even under conditions of energy deprivation in which they accumulate. Glucosidase inhibition in ER vesicle incubations likewise prevented the appearance of incompletely glucosylated oligosaccharide-lipids. Studies employing the mannosidase inhibitor 1-deoxymannojirimycin in thyroid slices furthermore indicated that in vivo removal of at least one mannose residue from the dolichyl pyrophosphate-linked oligosaccharide can occur.

Animals↗

PubMed1991

Liver collagen glucosyltransferase in experimental primary liver carcinoma.

Collagen glucosyltransferase activity (EC 2.4.1.66) was quantified in experimentally-induced liver carcinoma, murine schistosomiasis mansoni-induced liver fibrosis and compared to the level of enzyme activity in control liver samples. Enzyme activity in hepatoma and fibrotic tissues were 12 and 5 times the mean level of enzyme activity in the control liver tissue respectively. The level of enzyme activity in the hepatoma tissue was two times the level of enzyme activity found in the fibrotic tissue. The findings in this study provide the basis for the highly elevated serum values of this intracellular enzyme in experimentally-induced primary hepatocellular carcinoma or in human primary hepatoma. The enzyme activity may be increased in primary liver carcinoma to compensate for an increased rate of collagen synthesis.

Animals↗

PubMed1991

Partial characterization of the glucosyltransferases of an oral Streptococcus salivarius strain.

The oral Streptococcus salivarius strain S3 possessed extracellular glucosyltransferase (GTF) and cell-associated fructosyltransferase activities. Chromatofocusing column chromatography of crude GTF yielded multiple peak fractions, which were categorized into two types which catalysed (1) water-insoluble glucan synthesis and (2) water-soluble glucan formation. The GTF isozyme eluted in fraction 29 synthesized mutanase- and dextranase-sensitive insoluble glucan from sucrose, while fraction 81 GTF synthesized soluble glucan which was insensitive to both glucanases. The ability to agglutinate Streptococcus sobrinus cells was high for insoluble glucan but negligible for soluble glucan. The insoluble glucan-synthesizing activity of fraction 29 GTF was inhibited by the presence of dextran T10. Isoelectric focusing yielded a single activity band but SDS-polyacrylamide gel electrophoresis gave multiple bands for both GTF fractions 29 and 81. The extracellular crude GTF activity was inactivated by 0.1% SDS or 1% Tween 80, but the activity was completely restored by the addition of 1% Triton X-100.

Detergents↗

PubMed1989

[Streptococcus mutans glucosyltransferase: isolation and its ability to synthesize polysaccharides].

The extracellular glucosyltransferases (GTF, EC 2.4.1.5) were extracted from trypticase yeast L-cystine culture supernatant of streptococcus mutans strains SSMC 167(g), 6715(g), SSMC 100 (c) and Ingbritt (c) by 60% saturated ammonium sulphate precipitation. The yield was more than 50%. All the enzyme preparations could synthesize both water-soluble and insoluble glucans. The results of polyacrylamide gel electrophoresis of enzyme preparations illustrated the complexity and multicomponent nature of the GTF of S. mutans. The abilities of synthesizing polysaccharides were different between S. mutans serotype g and serotype c. The ability of synthesizing water-soluble glucan was almost the same as that of synthesizing water-insoluble glucan for GTFs from the two S. mutans strains of serotype g, but the ability of synthesizing water-soluble glucan was 10-fold to that of synthesizing water-insoluble glucan for GTFs from other two strains serotype c. No frucotosyltransferase activity was found.

Glucans↗

PubMed1989

Effect of magnesium ions on secretion of glucosyltransferase from Streptococcus sobrinus.

Magnesium ions, which are known to inhibit the leader peptidase (signal peptidase) activity of Escherichia coli, stimulated the activities of glucosyltransferases (GTFs) in culture medium of Streptococcus sobrinus at concentrations of 1 or 5 mM. At a concentration of 50 mM, the activity of water-soluble glucan synthase was not affected and that of water-insoluble glucan synthase was slightly suppressed. The activities of both GTFs in the crude enzyme extract were totally unaffected by addition of magnesium ions. These findings indicate that magnesium ions have some effects on secretion of the GTFs from S. sobrinus, but that the mechanism of transportation of the enzymes across the plasma membrane in S. sobrinus differs completely from that of proteins secreted into the periplasmic space or assembled in the outer membrane in E. coli.

Culture Media↗

PubMedDate not supplied

A simplified method for the partial purification and enzyme assay of glucosyltransferase from human dental plaque.

A simplified method for the partial purification and enzyme assay of glucosyltransferase from human dental plaque is described. The enzyme obtained has a reasonable specific activity for the assay of soluble and insoluble polysaccharides synthesis. This method may be useful for nonacquainted people with enzymological methods and of great utility in the in vitro evaluation of antiplaque substances.

Biological Assay↗

PubMed1989

[Glucosyltransferase (GTF) and immunization against dental caries in humans].

Glucosyltransferase (GTF) is an extracellular or cell-associated enzyme synthesized by the "mutans" group of streptococci as well as the S. sanguis and is responsible for the biosynthesis of extracellular polysaccharides. Glucan formation in dental plaque mediates binding of S. mutans and S. sanguis to one another as well as to other bacteria. Although the production of organic acids is an indispensable property of the cariogenic strains of bacteria, their ability to stick and accumulate on tooth surfaces is an almost equally significant parameter of virulence. Furthermore, GTF has been proven to be an effective antigen in eliciting caries-protective secretory IgA antibodies in rodent models. That led to the identification of GTF as a potential antigen for use in a human caries vaccine. The results of recent studies suggest that oral immunization with GTF, has the potential to elicit a secretory IgA antibody response and to interfere with accumulation and permanent colonization of S. mutans on smooth tooth surfaces. However, it cannot be inferred from the available data whether such a vaccine is effective in caries prevention in human beings. Although many modifications seem to be necessary with regard to the composition, dose, frequency and route of administration of the antigen, the preparation of a safe and effective vaccine against human caries is considered to be feasible in the near future.

Animals↗

PubMed1989

Effect of several resin monomers on water insoluble glucan formation by glucosyltransferase of Streptococcus sobrinus.

The cause or mechanism by which more plaque tend to accumulate on composite resins than on any other restorative materials has yet to be sufficiently explained. The purpose of this study was to investigate a possible mechanism by clarifying the effects of several monomers on the glucosyltransferase activity from Streptococcus sobrinus. The following results were obtained. In the individual resin monomers, di-, tri- and tetra-ethylene glycol dimethacrylate (2G, 3G and 4G), Bis-GMA and UDMA showed a stimulatory tendency of water insoluble glucan (WIG) formation. However, ethylene glycol dimethacrylate (IG), polyethylene glycol dimethacrylate (9G and 14G), and MMA diminished the synthesis of water soluble glucan as the concentration of monomers was increased. In addition, the eluate from experimental resin consisted of IG and Bis-GMA decreased the production of WIG when compared to that from 3G and Bis-GMA based resin. These results indicated that it was possible to develop a composite resin which inhibits plaque accumulation by using some antienzymatic monomers.

Composite Resins↗

PubMed1985

Salivary IgA antibody to glucosyltransferase in man.

Parotid salivas of 97 young adults were screened for IgA antibody to glucosyltransferase (GTF) from laboratory strains of Streptococcus mutans (serotypes c and g). Antibody levels to GTF from serotype c positively correlated with levels to serotype g GTF among these salivas. GTF's were prepared from S. mutans obtained from a subset of individuals in this population. All but one saliva showed IgA antibody activity to all of the GTF tested. In addition, the relative magnitude of each subject's antibody level was generally the highest to the GTF from their own S. mutans. Fractions, enriched for IgA by ammonium sulphate precipitation and gel filtration, showed patterns of functional inhibition of GTF activity which were consistent with patterns of IgA antibody activity in ELISA of unfractionated salivas. These data indicate that detectable levels of IgA antibody to S. mutans GTF exist in many young adult salivas, while this IgA antibody activity reacts with GTF from different biotypes, subjects generally show the highest secretory IgA antibody levels to their own GTF, and the relative amount of IgA antibody to GTF and the ability to inhibit GTF activity are roughly correlated.

Adolescent↗

PubMed1987

Purification and characterization of glucosyltransferase from Streptococcus mutans OMZ176 with chromatofocusing.

A crude glucosyltransferase (GTase) preparation of Streptococcus mutans OMZ176 was fractionated by chromatography on a chromatofocusing column. It was separated into three major fractions. Fractions 1 and 3 mainly synthesized water-soluble glucan (SG) without primer dextran T-10. Dextransucrase activity of fraction 1 was not increased by the primer, although that of fraction 3 was increased. Fraction 2 synthesized only water-insoluble glucan (IG) in the absence of a primer, but mutansucrase activity of this fraction was greatly increased dose-dependently by the addition of a primer. The SG and IG synthesized by fraction 1 were rich in alpha-1,6 glucosidic linkages. On the other hand, about 80% of glucose residues of the IG synthesized by fraction 2 were alpha-1,3 linked. Both SG and IG synthesized by fraction 3 contained highly branched structures.

Chromatography, Gel↗

PubMed1982

Effects of exogenous soluble dextrans on insoluble glucan synthesis by Streptococcus mutans glucosyltransferase.

Production of water-insoluble glucan (ISG) from sucrose by cell-free Streptococcus mutans AHT glucosyltransferase (GTF) first rapidly increased, and then sharply declined, as the amounts of water-soluble Dextrans T20 approximately T500 present, were increased. The decline of ISG synthesis was accompanied by an increased synthesis of the water-soluble fraction (SG). Prolonged incubation, however, induced enhanced synthesis of ISG even at higher dextran concentrations. The concentration of dextran required to stimulate or suppress ISG synthesis depended on the amounts of GTF used, but the extent of the stimulation was almost identical for the same GTF/dextran ratio. Thus, ISG synthesis is stimulated by the presence of dextrans at relatively low concentrations, but retarded at higher concentrations by being shifted to SG synthesis. ISG produced in the presence of dextrans contained higher proportions of alpha-1,6 glucosidic linkage and lower molecular size fractions, and possessed lower viscosity. These ISG products did not exhibit the coalescence of two component fibrils as observed with control ISG. These changes combined may contribute to the reduction of ISG-dependent adherence to glass of S. mutans cells by the presence of soluble dextrans, irrespective of their molecular size and concentration.

Adhesiveness↗

PubMed1981

The effect of surfactants upon the activity and distribution of glucosyltransferase in Streptococcus mutans 6715.

A modified Somogyi-Nelson procedure was used to determine the amount of reducing sugar produced during the reaction of S. mutans 6715 glucosyltransferase (GTF) with sucrose. This technique is an indirect measure of GTF activity and was used to determine the effects of the surfactants glycerol monolaurin (GML) and sodium lauryl sulfate (SLS) upon crude extracellular GTF. GML at 5, 10, and 15 micrograms/ml reduced culture filtrate GTF enzyme activity to an average of 81% of the control value. SLS at the only concentration tested (15 micrograms/ml) also caused a reduction, resulting in a GTF activity level that was 82% of the control value. Secondly, S. mutans 6715 cultures were grown in a medium containing Tween 80, or SLS. The cell-free culture filtrate and the cell-pellet were assayed separately for GTF activity. GML in the medium produced a decrease in culture filtrate GTF activity and an increased cell-pellet activity. The total (whole culture) activity for culture broths was 89% to 90% of the control value when 5, 10, or 15 micrograms/ml GML were added. Tween 80 supplemented culture medium resulted in increased culture filtrate GTF, while levels measured in the cell-pellet were decreased. Overall, Tween 80 caused a large increase in whole culture GTF activity. Cell cultures containing SLS at 15 micrograms/ml resulted in no change in the GTF activity as compared to the control, nor was there any change in the percent of GTF in the culture filtrate versus the percent which was in the cell-pellet. Higher concentrations of SLS could not be tested due to the inhibitory effect on cellular growth.

Fatty Alcohols↗

PubMed1983

Solubilization of the UDP-glucose:1,4-beta-D-glucan 4-beta-D-glucosyltransferase (cellulose synthase) from Acetobacter xylinum. A comparison of regulatory properties with those of the membrane-bound form of the enzyme.

A procedure has been developed for the effective solubilization of UDP-glucose:1,4-beta-D-glucan 4-beta-D-glucosyltransferase (cellulose synthase) by treatment of membranes from the bacterium Acetobacter xylinum with digitonin. Low concentrations of digitonin (0.1%, w/v) cause stimulation of the enzyme activity in membranes; treatment with higher concentrations of digitonin (1-10%) results in solubilization of up to 70% of the digitonin-stimulated activity. The digitonin-solubilized enzyme displays regulatory properties quite similar to those of the membrane-bound form of the enzyme, showing specific activation by GTP. GTP activation requires the presence of a protein factor which can be separated from the enzyme by washing the membranes prior to enzyme solubilization. Association of this protein factor with the membrane-bound enzyme is promoted by polyethylene glycol or by Ca2+; however, these compounds are ineffective in enhancing enzyme-factor association for the enzyme in the solubilized state. The observation that Ca2+ promotes enzyme-factor association in the membranes suggests that this cation, in addition to GTP, may play a role in the regulation of cellulose synthesis in vivo in A. xylinum.

Arabidopsis Proteins↗