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PubMed1996

Molecular cloning and identification of N-acyl-D-glucosamine 2-epimerase from porcine kidney as a renin-binding protein.

N-Acetylneuraminic acid (NeuAc) is an important molecule in biological recognition systems. NeuAc is known to be biosynthesized either from UDP-N-acetyl-D-glucosamine by an action of UDP-N-acetyl-D-glucosamine 2-epimerase or from N-acetyl-D-glucosamine by N-acyl-D-glucosamine 2-epimerase (GlcNAc 2-epimerase). However, the physiological function of the GlcNAc 2-epimerase in NeuAc biosynthesis has not been fully evaluated. To clarify the role of GlcNAc 2-epimerase in NeuAc biosynthesis, the enzyme and its gene were isolated from porcine kidney cortex. Escherichia coli cells transformed with the gene expressed the GlcNAc 2-epimerase having the same properties as those of the GlcNAc 2-epimerase from porcine kidney. Sequence analysis indicated that the gene was capable of synthesizing a 46.5-kDa protein (402 amino acids) with a conserved leucine zipper motif. Homology search for the cloned gene revealed that the GlcNAc 2-epimerase was identical with renin-binding protein (RnBP) in porcine kidney (Inoue, H., Fukui, K., Takahashi, S., and Miyake, Y.(1990) J. Biol. Chem. 265, 6556-6561) (identity: 99.6% in nucleotide sequence, 99.0% in amino acid sequence). That GlcNAc 2-epimerase is a RnBP was confirmed by its ability to bind porcine kidney renin and mask its protease activity. These findings provide unequivocal evidence that the enzyme GlcNAc 2-epimerase is a RnBP.

Amino Acid Sequence↗
PubMed1998

Effects of eicosapentaenoic acid and its 15-hydroperoxy and 15-hydroxy derivatives on glucosamine synthetase activity in rabbit gastric mucosa.

The effects of eicosapentaenoic acid and its 15-hydroperoxy and 15-hydroxy adducts on the activity of glucosamine synthetase, the rate-limiting enzyme of mucus synthesis, in rabbit gastric antral mucosa were examined. 15-Hydroperoxy-eicosapentaenoic acid inhibited the glucosamine synthetase activity at concentrations of 10, 20 and 50 microM. The effect was concentration-dependent, and the concentration required for 50% inhibition was approximately 20 microM. Eicosapentaenoic acid and its 15-hydroxy adduct had no significant effect on the enzyme activity at the same concentration range. The experiment utilizing Fe2+ revealed that the inhibitory effect of 15-hydroperoxyeicosapentaenoic acid on the glucosamine synthetase activity is not due to hydroxy radical which is expected to be formed from the hydroperoxy adduct. These results suggest that 15-hydroperoxyeicosapentaenoic acid has the potential to reduce the synthesis of gastric mucus by inhibiting the glucosamine synthetase activity.

Animals↗
PubMed2004

Poly-N-acetyl glucosamine-mediated red blood cell interactions.

BACKGROUND: Investigations were performed to assess the effect of poly-N-acetyl glucosamine (p-GlcNAc) fiber slurry-mediated hemostasis by interactions with red blood cells. METHODS: Red blood cell aggregation studies were performed using test material-coated microscope slides and multiphoton microscopic measurements. Enzymatic removal of red blood cell surface proteins was achieved using trypsin and neuraminidase treatment. Zeta-potential measurements (surface charge) were performed. RESULTS: Red blood cells interact directly with poly-N-acetyl glucosamine polymers through ionic interactions and cell-surface proteins. The effective concentration of poly-N-acetyl glucosamine fiber material for 50% red blood cell aggregation was 0.28 mg/mL. The p-GlcNAc beta-configuration fibers and an alpha-configuration structural modification of the fibers both produced maximal responses because of their zeta-potentials, whereas other chemically modified p-GlcNAcs and chitosans were ineffective. CONCLUSION: Poly-N-acetyl glucosamine-induced red blood cell aggregation is mediated by interactions with red blood cell surface charges.

Acetylglucosamine↗
PubMed2004

Mechanisms of poly-N-acetyl glucosamine polymer-mediated hemostasis: platelet interactions.

BACKGROUND: Investigations were performed to determine whether poly-N-acetyl glucosamine (p-GlcNAc) induces hemostasis by the activation of platelets. METHODS: Platelets were isolated from human blood, fixed in the presence poly-N-acetyl glucosamine fibers, and visualized with scanning electron microscopy. Platelet activation surface markers were measured by fluorescence multiphoton microscopy. Platelet aggregation in the presence of p-GlcNAc fibers and integrin receptor blockers was measured. RESULTS: Scanning electron microscopy indicated that contact of platelets with poly-N-acetyl glucosamine fibers resulted in platelet activation. Fluorescent microscopy showed that contact of platelets with the marine polymer increased intracellular levels of free calcium and resulted in surface exposure of platelet phosphatidylserine, P selectin, and the alphaIIbbeta3 integrin. Antibody inhibitors of the platelet alphaIIbbeta3 integrin inhibited p-GlcNAc to stimulate fibrin polymerization. CONCLUSION: Poly-N-acetyl glucosamine fiber material promotes hemostasis by the activation of platelets.

Acetylglucosamine↗
PubMed1985

Inhibition of glucosamine synthase by bacilysin and anticapsin.

L-Glutamine:D-fructose-6-phosphate amidotransferase ('glucosamine synthase', EC 5.3.1.19) from Escherichia coli MRE 600 was purified at least 75-fold. It catalysed the formation of 21.1 mumol glucosamine 6-phosphate (mg protein)-1 in 30 min at 37 degrees C. Its molecular weight, estimated by gel filtration, was about 90000 and it was inhibited by thiol group reagents. Anticapsin, the C-terminal amino acid of the dipeptide antibiotic bacilysin, and to a lesser extent bacilysin itself, inhibited glucosamine synthase activity. Kinetic studies indicated that the inhibition was non-competitive with respect to fructose 6-phosphate as substrate but partly competitive with respect to L-glutamine. Incubation of the enzyme with anticapsin brought about a time-dependent and irreversible inhibition. It is suggested that anticapsin behaves as a glutamine analogue and that a reaction of its epoxide group with a thiol group of glucosamine synthase results in its linkage to the enzyme by a covalent bond.

Alanine↗
PubMed1971

Growth Inhibition and Metabolite Pool Levels in Plant Tissues Fed d-Glucosamine and d-Galactose.

The growth of corn (Zea mays) roots and barley (Hordeum vulgare) coleoptiles is sensitive to the presence of external d-glucosamine and d-galactose. In order to investigate this effect, tissues were fed the radioactive monosaccharides at concentrations that ranged from those that were strongly inhibitory to those that had little influence on growth. At low concentrations, d-glucosamine is converted to uridine diphosphate-N-acetyl-d-glucosamine, phosphate esters of N-acetylglucosamine, and free N-acetylglucosamine. As the external concentrations were increased, the pool levels of each of these metabolites rose several fold; and, in corn roots, two unidentified compounds, which had not been detected previously, began to accumulate in the tissues. The major products of d-galactose metabolism were uridine diphosphate-d-galactose and d-galactose 1-phosphate at all the concentrations tested. Both these compounds showed a marked increase as the external galactose concentrations were raised to inhibitory levels. The experiments indicate that efficient pathways exist in plants for the metabolism of d-glucosamine and d-galactose. These pathways, however, do not appear to be under strict control, so that metabolites accumulate in unusually high amounts and presumably interfere competitively with normal carbohydrate metabolism.

Journal Article↗
PubMed1973

Partial Purification and Properties of d-Glucosamine 6-Phosphate N-Acetyltransferase from Phaseolus aureus.

d-Glucosamine-6-P N-acetyltransferase (EC 2.3.1.4) from mung bean seeds (Phaseolus aureus) was purified 313-fold by protamine sulfate and isoelectric precipitation, ammonium sulfate and acetone fractionation, and CM Sephadex column chromatography. The partially purified enzyme was highly specific for d-glucosamine-6-P. Neither d-glucosamine nor d-galactosamine could replace this substrate. The partially purified enzyme preparation was inhibited up to 50% by 2 x 10(-2)m EDTA, indicating the requirement of a divalent cation. Among divalent metal ions tested, Mg(2+) was required for maximum activity of the enzyme. Mn(2+) and Zn(2+) were inhibitory, while Co(2+) had no effect on the enzyme activity. The pH optimum of the enzyme in sodium acetate and sodium citrate buffers was found to be 5.2. The effect of Mg(2+) on the enzyme in sodium acetate and sodium citrate buffers was particularly noticeable in the range of optimum pH. Km values of 15.1 x 10(-4)m and 7.1 x 10(-4)m were obtained for d-glucosamine-6-P and acetyl CoA, respectively. The enzyme was completely inhibited by 1 x 10(-4)mp-hydroxymercuribenzoate, and this inhibition was partially reversed by l-cysteine; indicating the presence of sulfhydryl groups at or near the active site of the enzyme.

Journal Article↗
PubMed1994

Spectrochemical evidence for the presence of a tyrosine residue in the allosteric site of glucosamine-6-phosphate deaminase from Escherichia coli.

The interaction of the enzyme glucosamine 6-phosphate deaminase from Escherichia coli with its allosteric activator, N-acetyl-D-glucosamine 6-phosphate, was studied by different spectrophotometric methods. Analysis of the circular-dichroism differential spectra produced by the binding of the allosteric activator or the competitive inhibitor 2-amino-2-deoxy-D-glucitol 6-phosphate (a homotropic ligand displacing the allosteric equilibrium to the R conformer), strongly suggests the presence of tyrosine residues at or near the allosteric site, although a conformational effect cannot be ruled out. The involvement of a single tyrosine residue in the N-acetyl-D-glucosamine-6-phosphate binding site of glucosamine-6-phosphate deaminase was supported by spectrophotometric pH titrations performed in the presence or absence of the homotropic and heterotropic ligand. In these experiments, a single titrated tyrosine residue is completely protected by saturation with the allosteric activator; this group is considerably acidic (pK 8.75). The analysis of the amino acid sequence of the deaminase using a set of indices for the prediction of surface accessibility of amino acid residues, suggests that the involved residue may be Tyr121 or Tyr254.

Aldose-Ketose Isomerases↗
PubMed1987

Requirement of a properly acylated beta(1-6)-D-glucosamine disaccharide bisphosphate structure for efficient manifestation of full endotoxic and associated bioactivities of lipid A.

Several synthetic acylated glucosamine monophosphates, with structures corresponding to the nonreducing or reducing moiety of the lipid A of the Escherichia coli or Salmonella minnesota type, and a synthetic compound corresponding to a biosynthetic disaccharide lipid A precursor (designated Ia or IVA) were examined for their endotoxic and related bioactivities in comparison with those of the synthetic and bacterial parent molecules, i.e., acylated beta(1-6)-D-glucosamine disaccharide bisphosphates. Some of the test monosaccharide compounds were definitely active in most of the in vitro assays. Their activities, except for complement activation, however, were weaker than those of the reference compounds, synthetic and bacterial acylated disaccharide bisphosphates. The differences between the test monosaccharide and disaccharide compounds were much more apparent in in vivo assays, in which the test acylated glucosamine monophosphates were scarcely active, though some test compounds exhibited weak lethal toxicity in galactosamine-loaded mice and were weakly active in pyrogenicity, immunoadjuvant activity, and possible tumor necrosis factor and alpha and beta interferon-inducing ability in Mycobacterium bovis BCG- and Propionibacterium acnes-primed mice, respectively. Mixture at an equimolar ratio of acyl glucosamine monophosphates, each of which has the structure of the reducing or nonreducing moiety of the reference disaccharide compound, did not restore the endotoxic or associated bioactivities of the corresponding parent molecules. No essential differences in bioactivity were noted between synthetic and bacterial monosaccharide compounds, i.e., lipid X, whose structure corresponds to the reducing moiety of E. coli-type lipid A.

Acylation↗
PubMed2006

Filling of the aneurysmal sac with DEAC-glucosamine in an animal model of abdominal aortic aneurysm following stent-graft repair.

AIM: The aim of this study was to present the preliminary results of a technique of abdominal aortic aneurysm (AAA) sac filling in an attempt to obliterate the sac in a swine AAA model, using deacetylated-poly-N-acetyl glucosamine (DEAC-poly-N-acetyl glucosamine). METHODS: Eleven Yucatan pigs, 6 months of age, 40 kg -60 kg, were used to create an AAA with a Dacron pouch implanted surgically and left to mature for 2 weeks. One animal was used to establish the AAA creation procedures. Eight animals were used for AAA sac filling; of the 8 subjects 2 were used for acute studies, and 6 for longer-term studies. Two additional animals were used as controls without polymer sac filling. Two weeks after the AAA creation, a 13 mmx5.5 cm straight tube AneuRx stent-graft was placed to exclude the aneurysm. The aneurysmal sac was filled with a polymer, DEAC-poly-N-acetyl glucosamine at 1.5%, 70% deacetylated, mixed with iohexol. There was filling of a lumbar artery by the polymer in 2 animals. Endpoints were at 1, 2, 4, 6, 12 and 24 weeks, in the chronic study animals and 6 and 12 weeks in the control subjects, procedures consisting of aortography followed by necropsy and pathologic examination. RESULTS: The AAA creation and aneurysm sac filling was successful in all animals. An organized thrombus layer of about 2 mm in thickness was observed in all subjects along the Dacron aneurysm wall. All aneurysms were angiographically patent at the time of treatment, but fresher thrombus within the sac was seen in 4 subjects before the polymer injection. The stent-graft placement excluded the AAA sac and the polymer injection filled all AAA sacs. The AAA sac had acquired a firm rubbery consistency at the time of necropsy. There was mild inflammatory reaction to the Dacron material in the surrounding tissues and within the sac, to a lesser extent. Two animals developed paralysis of the hind limbs following treatment, most likely related to spinal ischemia, and were used as acute subjects. There was no recanalization of the aneurysm sac, during the follow-up time, ranging from 1 to 24 weeks in the treatment or control subjects. There was a 25% shrinkage of the AAA sac at 6th, 40% at 12th week and 75% by the 24th week. The 2 control subjects showed shrinkage of less than 25% at 6 and 12 weeks. There was replacement of the polymer/thrombus complex by connective tissue, fat tissue with capillary neovascularization in the treated subjects. Fibrosis and calcifications were also detected within the sac, mostly around the stent-graft and in contact with the aortic wall starting at 4 weeks. Control subjects did not show replacement of the thrombus by connective tissue or neovascularization. CONCLUSION: The results of this preliminary study support the aneurysm sac filling as a potential tool to exclude the aneurismal sac, promoting shrinkage of the AAA. DEAC -poly-N-acetyl glucosamine promotes clotting within the AAA sac with progressive replacement by connective tissue and neovascularization and may have a potential to prevent endoleaks. The polymer is easy to use, and it seems to have adequate gradual long-term replacement properties, preventing aneurysm sac recanalization.

Angiography↗
PubMed1996

Antiproliferative role of 3-O-sulfate glucosamine in heparin on cultured pulmonary artery smooth muscle cells.

Heparin macromolecules inhibit vascular remodeling associated with hypoxic pulmonary hypertension. Heparin's antiproliferative effect on smooth muscle cells, based on studies of synthetic pentasaccharide fragments, has been attributed to 3-O-sulfate on the internal glucosamine. To determine the role of 3-O-sulfation in smooth muscle cell growth, we treated three heparins of varying potency with heparitinases I and II, which degrade heparin fragments containing 3-O-sulfate on the glucosamine residue to delta-tetrasaccharides only. Our most antiproliferative heparin gave the least amount of delta-tetrasaccharides. This heparin was then fractionated according to degree of sulfation using ETOH precipitation. Again we found no antiproliferative difference between the highly sulfated fractions and those with a lesser degree of sulfation. These studies suggest that 3-O-sulfate of glucosamine residue is not critical in whole heparins for antiproliferative activity.

Animals↗
PubMed1977

Glucosamine resistance in yeast. II. Cytoplasmic determinants conferring resistance.

Two cytoplasmic, glucosamine resistant (GR) mutants of Saccharomyces cerevisiae, GR6 and GR10, were crossed to strains bearing known mitochondrial markers. Analysis of vegetative and meiotic segregation patterns in these crosses suggested that the glucosamine resistance conferring factor did not reside on mitDNA. This was confirmed by ethidium bromide treatments which completely abolished oligomycin resistance due to a mitochondrial mutation at the OL12 locus but which failed to eliminate the GR factor present in the same strain. Comparison of GR6 and GR10 to some other known cytoplasmic determinants suggested that while glucosamine resistance is not related to the killer plasmid it may be allelic to the URE3 determinant and/or to the PSI factor.

Chromosome Mapping↗
PubMed1986

Quantitation of glycosaminoglycan metabolism in anatomically intact articular cartilage of the mouse patella: in vitro and in vivo studies with 35S-sulfate, 3H-glucosamine, and 3H-acetate.

We investigated the usefulness of the whole mouse patella to quantitate the synthesis of the glycosaminoglycan (GAG) backbone and its sulfation by intact murine articular cartilage, both in vitro and in vivo. Using 35S-sulfate, 3H-glucosamine, or 3H-acetate as precursors of GAG synthesis, it was found that more than 90% of the incorporated radioactivity was confined to the patellar cartilage layer compared to the whole patella. Overnight papain digestion was enough to liberate more than 95% of the incorporated radiolabels, except for 3H-acetate for which 15-25% was not digestible. Comparison of radioactivity in the patella and that in quantitatively isolated GAGs revealed that for 35S-sulfate incorporation studies the whole patella can be used as a reliable measure for sulfated GAG synthesis. The situation was different for the GAG backbone precursors 3H-glucosamine and 3H-acetate; more than 50% of the 3H labels were incorporated into compounds other than GAGs or non-covalently associated with matrix components. Hence, in studying GAG-backbone metabolism, polysaccharides must be isolated quantitatively from cartilage. In vivo studies made it clear that both 35S-sulfate and 3H-glucosamine are incorporated into patellar GAGs in amounts high enough to enable proper quantitation and that the route of administration (intraperitoneally or intravenously) is of minor importance. Due to its low specificity for cartilage GAGs, 3H-acetate is not suitable for such studies.

Acetates↗
PubMed1980

Action of glucosamine on acetylcholine-sensitive channels.

The action of glucosamine was studied on voltage clamped neurones of Aplysia, presenting an excitatory response to acetylcholine. Noise and relaxation experiments show that glucosamine increases the mean channel open time and reduces the amplitude of the elementary current associated with the acetylcholine response. Both effects are enhanced by hyperpolarization of the cell membrane. The results are interpreted by a model assuming glucosamine binding to open channels. This binding impedes the flow of permeant ions and decreases the closing rate of the channels.

Acetylcholine↗
PubMed2004

The use of glucosamine therapy in osteoarthritis.

Glucosamine products have been used extensively for the management of pain in osteoarthritis. This paper reviews the most recent clinical and experimental studies regarding its efficacy and safety. Although clinical trials include methodologic flaws and publication bias, glucosamine is likely an effective therapy for the symptomatic management of osteoarthritis. In turn, definite proof for chondromodulating effect requires well-conducted clinical trials. In North America, glucosamine is an over-the-counter dietary supplement and preparations made by different manufacturers may vary. There is also a need to standardize this therapy and allow practitioners to give patients suitable advice. An ongoing long-term clinical trial in the US will possibly permit to investigate the clinical relevance of these results and give appropriate recommendations.

Clinical Trials as Topic↗
PubMed2004

The use of glucosamine therapy in osteoarthritis.

Glucosamine products have been used extensively for the management of pain in osteoarthritis. This paper reviews the most recent clinical and experimental studies regarding its efficacy and safety. Although clinical trials include methodologic flaws and publication bias, glucosamine is likely an effective therapy for the symptomatic management of osteoarthritis. In turn, definite proof for chondromodulating effect requires well-conducted clinical trials. In North America, glucosamine is an over-the-counter dietary supplement and preparations made by different manufacturers may vary. There is also a need to standardize this therapy and allow practitioners to give patients suitable advice. An ongoing long-term clinical trial in the US will possibly permit to investigate the clinical relevance of these results and give appropriate recommendations.

Cartilage, Articular↗
PubMed1992

Influence of D(+)-glucosamine on infection rates and parasite loads in tsetse flies (Glossina spp.) infected with Trypanosoma brucei.

Teneral Glossina morsitans centralis, G. m. morsitans and G. pallidipes were infected with three different clones of Trypanosoma brucei in blood containing D(+)-glucosamine, an inhibitor of tsetse midgut lectin. On average, 5 days of D(+)-glucosamine treatment tripled infection rates, without affecting the proportion of infections that matured. Total infection rates were equal in males and females, but twice as many infections matured in males. Counts of parasites in the guts and salivary glands of 277 flies revealed order of magnitude differences among flies, with females consistently having 2-3-times as many parasites as males. Parasite numbers varied in a sex-specific manner among tsetse-clone combinations, but these differences were not correlated with similar large differences in infection rates. D(+)-glucosamine treatment had no significant effect on parasite loads.

Animals↗