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At least 703 records · Page 39Linked to original sources
PubMed2002

Widespread N-acetyl-D-glucosamine uptake among pelagic marine bacteria and its ecological implications.

Dissolved free and combined N-acetyl-D-glucosamine (NAG) is among the largest pools of amino sugars in the ocean. NAG is a main structural component in chitin and a substantial constituent of bacterial peptidoglycan and lipopolysaccharides. We studied the distribution and kinetics of NAG uptake by the phosphoenolpyruvate:NAG phosphotransferase systems (PTS) in marine bacterial isolates and natural bacterial assemblages in near-shore waters. Of 78 bacterial isolates examined, 60 took up 3H-NAG, while 18 showed no uptake. No systematic pattern in NAG uptake capability relative to phylogenetic affiliation was found, except that all isolates within Vibrionaceae took up NAG. Among 12 isolates, some showed large differences in the relationship between polymer hydrolysis (measured as chitobiase activity) and uptake of the NAG, the hydrolysis product. Pool turnover time and estimated maximum ambient concentration of dissolved NAG in samples off Scripps Pier (La Jolla, Calif.) were 5.9 +/- 3.0 days (n = 10) and 5.2 +/- 0.9 nM (n = 3), respectively. Carbohydrate competition experiments indicated that glucose, glucosamine, mannose, and fructose were taken up by the same system as NAG. Sensitivity to the antibiotic and NAG structural analog streptozotocin (STZ) was developed into a culture-independent approach, which demonstrated that approximately one-third of bacteria in natural marine assemblages that were synthesizing DNA took up NAG. Isolates possessing a NAG PTS system were found to be predominantly facultative anaerobes. These results suggest the hypothesis that a substantial fraction of bacteria in natural pelagic assemblages are facultative anaerobes. The adaptive value of fermentative metabolism in the pelagic environment is potentially significant, e.g., to bacteria colonizing microenvironments such as marine snow that may experience periodic O2-limitation.

Acetylglucosamine↗
PubMed1989

Immunopharmacological activities of 2-keto-3-deoxyoctonic acid-(alpha 2----6)-linked 4-O-phosphono-D-glucosamine derivatives carrying N- and 3-O-acyl substituents.

The immunopharmacological activities of 2-keto-3-deoxyoctonic acid (KDO)-(alpha 2----6)-linked lipid A-subunit analogs, 4-O-phosphono-D-glucosamine derivatives carrying N- and 3-O-acyl substituents, were compared with those of the corresponding analogs without KDO, GLA-27, GLA-47, and GLA-60. Among the analogs tested, GLA-60, a 4-O-phosphono-D-glucosamine carrying N-3-hydroxytetradecanoyl and 3-O-3-tetradecanoyloxytetradecanoyl groups, exhibited the most intensive activities in terms of mitogenicity, adjuvanticity, and mediator (tumor necrosis factor and colony-stimulating factor) induction. Binding (alpha 2----6) of KDO to GLA-60 failed to enhance the activities. Similarly, the activities of GLA-27 and GLA-47 were also decreased by introduction of KDO to the O-6 of the analogs. This indicates that the strengths of the activities of the subunit analogs depend on the kinds of N- and 3-O-linked acyl substituents and not on the presence of the KDO linked to the O-6.

Adjuvants, Immunologic↗
PubMed2006

N-acetyl-d-glucosamine induces the expression of multidrug exporter genes, mdtEF, via catabolite activation in Escherichia coli.

The expression of MdtEF, a multidrug exporter in Escherichia coli, is positively controlled through multiple signaling pathways, but little is known about signals that induce MdtEF expression. In this study, we investigated compounds that induce the expression of the mdtEF genes and found that out of 20 drug exporter genes in E. coli, the expression of mdtEF is greatly induced by N-acetyl-d-glucosamine (GlcNAc). The induction of mdtEF by GlcNAc is not mediated by the evgSA, ydeO, gadX, and rpoS signaling pathways that have been known to regulate mdtEF expression. On the other hand, deletion of the nagE gene, encoding the phosphotransferase (PTS) system for GlcNAc, prevented induction by GlcNAc. The induction of mdtEF by GlcNAc was also greatly inhibited by the addition of cyclic AMP (cAMP) and completely abolished upon deletion of the cAMP receptor protein gene (crp). Other PTS sugars, glucose and d-glucosamine, also induced mdtEF gene expression. These results suggest that mdtEF expression is stimulated through catabolite control.

Acetylglucosamine↗
PubMed1986

Identification of two new hemagglutinins of Escherichia coli, N-acetyl-D-glucosamine-specific fimbriae and a blood group M-specific agglutinin, by cloning the corresponding genes in Escherichia coli K-12.

Genes encoding the Escherichia coli IH11165 hemagglutinins with specificity for terminal N-acetyl-D-glucosamine and blood group M antigen, respectively, were cloned by a cosmid cloning procedure. A 22-kilobase-pair subclone expressed both hemagglutination specificities in the nonhemagglutinating E. coli HB101 recipient strain. Derivatives obtained by insertion and deletion mutagenesis expressed either one of the two hemagglutination specificities. Both agglutinins were purified; the agglutinin recognizing terminal N-acetyl-D-glucosamine was associated with a new type of fimbria (G fimbria) with an apparent subunit molecular mass of 19.5 kilodaltons, whereas the blood group M agglutinin (M agglutinin) was nonfimbrial and had an apparent subunit mass of 21 kilodaltons.

Acetylglucosamine↗
PubMed1995

The Escherichia coli G-fimbrial lectin protein participates both in fimbrial biogenesis and in recognition of the receptor N-acetyl-D-glucosamine.

The gafD gene encoding the N-acetyl-D-glucosamine-specific fimbrial lectin (adhesin) protein GafD of uropathogenic Escherichia coli was cloned and subjected to genetic analysis. The corresponding gene product was isolated as a MalE fusion protein. The lectin gene was identified with the aid of deletion mutagenesis; mutations in gafD impaired either receptor binding or both receptor binding and fimbria production, depending on the mutation created. All mutants converted to wild-type expressors when complemented in trans with the cloned intact gafD gene. The predicted 354-amino-acid sequence of GafD, deduced from the nucleotide sequence, is closely related to those of the fimbria-associated F17-G and F17b-G proteins coded for by enterotoxigenic and invasive E. coli strains. Isolated GafD was shown to recognize N-acetyl-D-glucosamine by virtue of specific binding to an immobilized receptor, thus proving directly that GafD is a sugar-binding protein. Our results indicate that GafD as such is sufficient for receptor recognition and that the protein also participates in fimbrial biogenesis.

Acetylglucosamine↗
PubMedDate not supplied

Utility of 3-O-methyl-N-acetyl-D-glucosamine, an N-acetylglucosamine kinase inhibitor, for accurate assay of glucokinase in pancreatic islets and liver.

Glucokinase, an enzyme that catalyzes the phosphorylation of glucose, constitutes the key regulatory step in glucose metabolism in pancreatic islets and liver. We found that 3-O-methyl-N-acetyl-D-glucosamine (3-O-methyl-GlcNAc) potently inhibits glucose phosphorylation by N-acetylglucosamine kinase whereas glucokinase is not at all affected by this hexosamine. The addition of 3-O-methyl-GlcNAc to the assay system for glucokinase in rat liver extracts, which contain a high activity of glucokinase (glucose as substrate) relative to N-acetylglucosamine kinase (N-acetyl-D-glucosamine as substrate), affected neither Km nor Vmax values of glucokinase. On the other hand, both Km and Vmax values of glucokinase in rat pancreatic islet extracts, in which N-acetylglucosamine kinase activity is higher than glucokinase activity, were significantly lowered by the use of 3-O-methyl-GlcNAc as an inhibitor of N-acetylglucosamine kinase.

Acetylglucosamine↗
PubMed1995

Amide and ester derivatives of N3-trans-epoxysuccinoyl-L-2,3-diaminopropanoic acid: inhibitors of glucosamine-6-phosphate synthase.

Several analogs 5, 6, 7, 8, 10 and 11 of the C-terminal fragment of a peptide antibiotic Sch 37137 were designed and tested as inhibitors of glucosamine-6-phosphate synthase from Saccharomyces cerevisiae. From IC50 values and kinetic parameters of inhibition of glucosamine-6-phosphate synthase by compounds 5-11 it has been found that the inhibitory potency of these compounds follows the order: 6 > 5 > 8 > 9 > 7, 10, 11. This suggests that an inhibitor with a primary amido group binds better to the active site of the enzyme than other inhibitors. The order of reactivity of compounds 5-11 may be attributed to a steric inability of the inhibitor to fit into the active site of the enzyme and also indicates the importance of the chirality of trans-epoxysuccinic acid on the inhibitory properties of the synthesized compounds.

Amides↗
PubMed1982

Elevation of glucosamine 6-phosphate synthetase activity in bleomycin-induced pulmonary fibrosis in hamsters.

The single intratracheal instillation of bleomycin sulfate (0.5 mg (potency) per 100 g body weight) in hamsters rapidly increased the activity of glucosamine 6-phosphate synthetase (EC 2.6.1.16) of the lung, a major regulatory enzyme for the synthesis of acidic glycosaminoglycan (AGAG). The activity increased as early as day 2, reached maximum level at day 10, then decreased and returned to the control level at day 45. The content of AGAG was also increased by bleomycin treatment, but the increase of AGAG followed the elevation of the enzyme activity. These results suggest that the early elevation of glucosamine 6-phosphate synthetase activity is closely related to the accumulation of AGAG in the fibrosing lung caused by bleomycin.

Aldose-Ketose Isomerases↗
PubMed1983

Peplomycin sulfate and pulmonary fibrosis: hydroxyproline, uronic acid, proline hydroxylase and glucosamine 6-phosphate synthetase in lungs of hamsters treated with peplomycin.

Effect of peplomycin sulfate (PLM) on pulmonary fibrosis was examined. Hydroxyproline, uronic acid, proline hydroxylase (EC 1.14.11.2) and glucosamine 6-phosphate synthetase (EC 2.6.1.16) in lungs of hamsters treated with PLM were studied and compared with those of hamsters treated with bleomycin (BLM). PLM, when administered intraperitoneally, one injection daily for 10 consecutive days, at either a high- (5 mg/kg) or low- (2.8 mg/kg) dosage-level, caused no significant increase of lung hydroxyproline and uronic acid as compared with controls. BLM on the other hand effected a significant increase in lung hydroxyproline on the high-dosage level (5 mg/kg) but not on the low-dosage level (2.8 mg/kg). In contrast, when administering PLM intratracheally, the concentrations of hydroxyproline in lungs increased 20% over the control levels. A transient increase of proline hydroxylase and glucosamine 6-phosphate synthetase also occurred shortly after the instillation. These increases were also observed in the corresponding groups treated with BLM, which confirmed the previous observations by other investigators. However, the magnitude of the increase was relatively lower in those values of PLM as compared with those of BLM. These data suggested that (1) PLM, when administered with multiple dosages intraperitoneally, showed no significant effect on the elevation of lung hydroxyproline; (2) PLM, when administered with a dose intratracheally, induced pulmonary fibrosis similar to that caused by BLM. However, the hydroxyproline accumulation in lungs of PLM-treated hamsters was less than in those of the BLM-treated; (3) The fibrotic effect on the lungs caused by either PLM or BLM was probably attributed to acceleration of the syntheses of collagen and acidic glycosaminoglycans.

Animals↗
PubMed2001

Isomerase activity of the C-terminal fructose-6-phosphate binding domain of glucosamine-6-phosphate synthase from Escherichia coli.

The isomerase activity of the C-terminal fructose-6P binding domain (residues 241-608) of glucosamine-6-phosphate synthase from Escherichia coli has been studied. The equilibrium constant of the C-terminal domain k(eq) ([glucose-6P]/[fructose-6-P]) = 5.0. A non-competitive product inhibition of the isomerase activity by the reaction product glucose-6-P has been detected. The existence of more than one binding and reaction sites for the substrate fructose-6P on the molecule of glucosamine-6-phosphate synthase can be expected. The fructose-6P binding domain possibly includes a regulatory site, different from the catalytic center of the enzyme.

Amino Acid Sequence↗
PubMed1999

[Glucosamine in the blood serum of young people with diabetes mellitus type 1].

The observations of some authors have shown that prolonged hyperglycemia may increase the process of hexosamin biosynthesis. The purpose of our study was to determine glucosamine levels in young patients with poorly controlled diabetes mellitus type 1. The study group consisted of 31 girls and boys whose ages ranged from 7 to 17 and who were newly diagnosed with type 1 diabetes mellitus. The diagnosis of diabetes mellitus was based on increased anti-insulin antibody levels, raised glycated hemoglobin and glucose concentrations and decreased insulin and C-peptide levels. In the studied group impairments in acid-base homeostasis as well as a correlation between the degree of blood acidification and free fatty acids, total cholesterol, and triglyceride levels were found. Despite evident hyperglycemia observed in all patients, glucosamine levels were within the normal range. Based on the present and previous investigations, where we observed increased hexosamine levels only in patients with hyperinsulinemia, we can draw the conclusion that increased enzymatic glycation of proteins requires not only increased glucose but also insulin access.

English Abstract↗
PubMed1990

Sequence of a cDNA that specifies the uridine diphosphate N-acetyl-D-glucosamine:dolichol phosphate N-acetylglucosamine-1-phosphate transferase from Chinese hamster ovary cells.

We have isolated a portion of the uridine diphosphate N-acetyl-D-glucosamine:dolichol phosphate N-acetyl-glucosamine-1-phosphate transferase gene (GTR2) from the genome of a tunicamycin-resistant clonal Chinese hamster ovary cell line, 3E11. The genomic fragment was selected by its hybridization to the yeast ALG-7 gene at low stringency. A 2.46-kilobase cDNA was isolated from a library prepared from 3E11 mRNA and probed with GTR2. The cDNA contained an open reading frame that encodes a protein of 408 amino acids with a molecular mass of 44.9 kDa. This protein was 43% identical in amino acid sequence to the protein of 448 amino acids encoded by the ALG-7 gene. The GTR2 gene fragment contained sequences for four exons coding for the carboxyl-terminal half of the protein. Transferase DNA sequences in 3E11 cells were 12-fold elevated over wild-type cells and 25-fold elevated when 3E11 cells were grown in the presence of tunicamycin. Transferase RNA levels in 3E11 cells were also elevated over wild-type levels but appeared unchanged by the presence of tunicamycin in the medium.

Amino Acid Sequence↗
PubMed1991

Dependence of the C-6 sulfate of the glucosamine moiety and 1----4 glycosidic linkage of heparin disaccharides for production of hemorrhage: reversal of the antihemostatic activity of heparin and their fragments by adenosine triphosphate and myosin.

Topical application or intraperitoneal injection of heparin and heparin oligosaccharides produces a potent inhibition of skin hemostasis. Studies conducted with disaccharides derived from heparin, heparan sulfate, and chondroitin sulfates have shown that delta-4,5-uronyl-(1----4)-glucosamine, bearing a sulfate at the C-6 position of the glucosamine residue, is the minimum structure for the antihemostatic activity. The disaccharides with this basic structure produce uncontrollable hemorrhage from small blood vessels, similar to that observed for heparin. The finding that other sulfated disaccharides, with the same sulfate to hexosamine to uronic acid ratios but with the sulfate at a different position (C-2) or with a different glycosidic linkage (1----3), were inactive as inhibitors of hemostasis indicates that a specific structure is needed to produce the effect. The inhibitory activity of the normal hemostatic process produced by heparin and its products could be reversed either by ATP or myosin. Molecular models show that part of the disaccharide inhibitors and ATP have a similar structural conformation.

Adenosine Triphosphate↗
PubMedDate not supplied

Inhibition of elastase enzyme release from human polymorphonuclear leukocytes by N-acetyl-galactosamine and N-acetyl-glucosamine.

We studied the effect of aminosugars on the elastase enzyme released from cytochalasin-B treated polymorphonuclear neutrophils (PMN) and stimulated by F-Met-Leu-Phe (FMLP). Both N-acetyl-galactosamine and N-acetyl-glucosamine can inhibit the release of leukocyte elastase enzyme. N-acetyl-galactosamine was a potent inhibitor of elastase enzyme release in a dose-related fashion. Inhibition ranged from 91.9% up to total inhibition. N-acetyl-glucosamine showed a mild inhibitory effect on elastase enzyme release; however, it too acted in a dose-related fashion. The range of inhibition was 17.17%-8.18%. Mannosamine showed an inhibitory effect in some donors, but this effect was not statistically significant. No effect on elastase enzyme release was shown with other sugars such as D-glucose and L-fucose. These results show that N-acetyl-galactosamine can inhibit the respiratory burst, which suggests that the aminosugars might do more than interfere with the carbohydrate lectin interaction.

Acetylgalactosamine↗
PubMed1990

N-[18F]fluoroacetyl-D-glucosamine: a potential agent for cancer diagnosis.

Positron labeled substrates such as sugars, amino acids, and nucleosides have been investigated for the in-vivo evaluation of biochemical processes in cancerous tissue. Hexosamines are obligatory structural components of many biologically important macromolecules, including membrane glycoproteins and mucopolysaccharide. We evaluated a new synthesized pharmaceutical, N-[18F]fluoroacetyl-D-glucosamine (18F-FAG), which is a structural analog of N-acetyl-D-glucosamine. C3H/HeMsNRS mice bearing spontaneous hepatomas were used for the tissue distribution study. At 60 min after injection, high uptakes were found in tumor (5.16, mean value of %dose/g), liver (3.71), and kidney (3.27). The tumor uptake of 18F-FAG showed the highest value in all tissue. In the PET study, VX-2 carcinoma of the rabbit was clearly visualized. Our preliminary results suggest that 18F-FAG has potential as a new agent for tumor imaging.

Acetylglucosamine↗
PubMed1986

Anticapsin: an active site directed inhibitor of glucosamine-6-phosphate synthetase from Candida albicans.

L-beta-(2,3-epoxycyclohexanono-4)-alanine, an active fragment of the antibiotic tetaine, identical to the antimetabolite anticapsin, is a powerful inhibitor of partially purified glucosamine-6-phosphate synthetase (2-amino-2-deoxy-D-glucose-6-phosphate ketol isomerase, aminotransferring, EC 5.3.1.19) from pathogenic fungus Candida albicans. Anticapsin was demonstrated to be a competitive inhibitor of this enzyme with respect to L-glutamine and uncompetitive with respect to D-fructose-6-phosphate. Incubation of anticapsin with glucosamine-6-phosphate synthetase in the absence of glutamine led to the formation of an inactive enzyme, irreversibly modified. The inactivation obeyed saturation kinetics; the determined Kinact was 9.5 X 10(-6) M. Addition of glutamine protected the enzyme against inactivation by anticapsin. Reaction of anticapsin with the enzyme exhibited characteristics of affinity labelling of the glutamine binding site. Probably the inactivation proceeds via an alkylation of cysteine residue at the glutamine binding site.

Alanine↗
PubMed1979

Characterization of rat hepatoma glucosamine 6-phosphate synthase and its relation to liver and fetal forms.

Glucosamine 6-phosphate synthase (EC 5.3.1.19) purified from various rat tissues by a procedure involving chromatography on diethylaminoethyl Sephadex and hydroxylapatite were characterized by means of isoelectric focusing. The non-hepatic isozyme, previously reported to be present in Yoshida sarcoma, has a pI of 4.1 and is distinguished from the hepatic isozyme, with a pI of 5.0. The pI 4.1 form is the major one in all of the fast-growing, transplantable hepatomas studied. Although not detectable in 19-day fetal liver or normal adult liver, the pI 4.1 form has been observed in the whole 12-day fetus and adult brain as almost the sole form of glucosamine 6-phosphate synthase.

Animals↗