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PubMed1984

Brugia malayi: stage-specific expression of carbohydrates containing N-acetyl-D-glucosamine on the sheathed surfaces of microfilariae.

Microfilariae, infective larvae, and adult worms of Brugia malayi were incubated with a panel of seven lectins in order to study the expression of surface carbohydrates. Infective larvae and adult worms did not bind any of the lectins utilized. Microfilariae, on the other hand, bound wheat germ agglutinin. The binding of this lectin was saturable and specific, and attributed to the presence of N-acetyl-D-glucosamine. In addition, microfilariae derived in vitro bound concanavalin A, indicating the presence of glucose and/or mannose on this stage of the parasite. The fact that similar concanavalin A binding was not seen on microfilariae recovered directly from the infected host implies that there is masking or loss of parasite surface antigens as microfilariae mature in vivo.

Acetylglucosamine↗
PubMed1983

Difference between tortoise and hen lysozymes in the mode of association with N-acetyl D-glucosamine as revealed by proton magnetic resonance spectroscopy.

Tortoise lysozyme, unlike hen lysozyme, does not distinguish between the alpha- and beta-anomeric forms of N-acetyl D-glucosamine. This indicates that alpha- and beta-anomeric forms of the inhibitor have the same affinities and experience identical magnetic environments in tortoise lysozyme. The dissociation constant of tortoise lysozyme-inhibitor complex was calculated from chemical shift data and found to be 3.5 X 10(-2) M. The enthalpy of dissociation was calculated to be 5.0 kcal/mol.

Acetylglucosamine↗
PubMed1988

Effect of chemical modification at C1 of the glucosamine backbone of lipid A-subunit analog GLA-27 on manifestation of immunopharmacological activity.

The effect of chemical modification at the C1 position of GLA-27, 4-O-phosphono-D-glucosamine carrying N-3-tetradecanoyloxytetradecanoyl [C14-O-(C14)] and 3-O-tetradecanoyl (C14) groups, was investigated. Replacement by SH or S-acetyl groups of the OH group resulted in the enhancement of mitogenicity but gave rise to a reduction, in macrophage-stimulating ability such as induction of tumor necrosis factor and enhancement of phagocytic and cellular acid phosphatase activities. Bisphosphorylation at C1 and C4 resulted in a slight decrease in mitogenicity or almost complete loss of the macrophage-stimulating ability.

Animals↗
PubMed1994

Predominant role of the substituents on the hydroxyl groups of 3-hydroxy fatty acids of non-reducing glucosamine in lipid A for the endotoxic and antagonistic activity.

The synthetic disaccharide precursor of lipid A (406: identical to lipid IVA) was found to reduce its endotoxic activity in mice by an order of 10(5) or more, by replacing the hydroxyl groups with succinyl or acetyl residues. Both the succinylated and acetylated 406 were also found to antagonize the endotoxic mitogenicity on murine splenocytes. Previous studies demonstrated that the succinylated or acetylated synthetic complete lipid A preparations retained the whole endotoxic activity [1994, Infect. Immunol. 62, 1705]. The drastic contrast in all of these results suggests the importance of the substituents on the hydroxyl groups of 3-hydroxy fatty acids of non-reducing glucosamine of lipid A for the activity and for transformation to the antagonistic structure.

Acetylation↗
PubMed1992

Enhanced incorporation of [14C]glucosamine into glycosaminoglycans of aortic neointima of balloon-injured and cholesterol-fed rabbits in vitro.

Glycosaminoglycans (GAG), which form the elementary constituent of extracellular matrix proteoglycans (PG), are implicated in the pathogenesis of atherosclerosis, mainly due to their lipoprotein binding capability and their abundance in a developing lesion during atherogenesis. However, the reasons for the increment of GAG content are poorly understood. In the present study, the influence of two well known atherogenic factors on arterial GAG synthesis were examined by estimating the incorporation of [14C]glucosamine into aortic GAG in an in vitro incubation system. Radioactivity associated with GAG was taken to represent their synthesis. GAG synthesis by neointimal tissue of rabbit aortas, 12 weeks following balloon catheter deendothelialization was measured and compared in rabbits fed a normal or 0.25% cholesterol supplemented diet for the preceding 6 weeks. In normolipaemic rabbits synthesis was found to be 12,438 +/- 173, 17,884 +/- 1390 and 15,960 +/- 1355 dpm/mg dry defatted tissue from uninjured (control), deendothelialized (DEA) and reendothelialized (REA) areas of rabbit aortas, respectively. This incorporation of radioactivity was significantly greater in hypercholesterolaemic rabbits corresponding to 13,426 +/- 239, 32,670 +/- 3077 and 27,496 +/- 3287 in the control, DEA and REA, respectively. The results demonstrated a synergistic effect of cholesterol feeding and arterial endothelial denudation in stimulating GAG synthesis. Although GAG synthesis was found to be stimulated by either cholesterol feeding or arterial injury, the stimulation by cholesterol feeding alone was only marginal. Further, results show a much higher retention of newly synthesized GAG by the tissue from REA. This study provided a possible explanation for increased GAG content in a developing proliferative lesion.

Animals↗
PubMed1983

Autoradiographic and fine structural study of chitin deposition in the cuticle of a barnacle using [3H]-D-glucosamine incorporation.

[3H]-D-Glucosamine was injected into the rostral sinus of Balanus eburneus (barnacle) and the distribution of labelled chitin in the cuticle was studied with autoradiography and electron microscopy. When the pattern of labelling was examined in different body regions of the same organism where thickness of fully formed cuticle varied, it was observed that the rate of chitin deposition varied, being greater in thick than in thin regions. The density of Ag grains overlying cuticle was also greater in the thick regions. When the pattern of labelling was examined in regions of cuticle, comparable in thickness, taken from a series of organisms sacrificed at different time points a comparable value for the rate of chitin deposition was obtained. In addition, asynchrony in deposition of cuticle in different body regions of the same organism as well as uptake of the label by substances other than chitin, i.e. glycogen and glycoproteins were described.

Animals↗
PubMed1991

Glucosamine oligomers: 2. N.m.r. studies on a DP3.

This paper concerns the characterization of the chemical structure of a DP3 glucosamine oligomer. The assignments of nearly all protons are reported. Variations of 1H chemical shifts with pD and temperature are correlated to the pKa of amino groups, and not with substantial conformational changes.

Carbohydrate Conformation↗
PubMed1992

Glucosamine oligomers: 4. Solid state-crystallization and sustained dissolution.

When glucosamine oligomers are stored in the solid state they undergo a process of crystallization. The extent to which this occurs depends on whether the samples are isolated in the -NH3+ or -NH2 form, on the storage time, and on the degree of polymerization of the isolated oligomer. The allomorph obtained by this process seems to correspond to the so-called 'tendon-chitosan'. Dissolution of such aged oligomer samples gives rise to a process of dissociation of the associated chains in the crystal, leading to the establishment of a pseudo-equilibrium between single and associated oligomer chains and hence the simultaneous presence of the 'monomeric', 'dimeric', 'trimeric', etc., forms of the oligomer. The phenomenon cannot be attributed to a process of aggregation in solution. The effects of various parameters on this behaviour have been investigated.

Chromatography↗
PubMed1984

Fine specificity of a monoclonal anti-testicular cell antibody for glycolipids with terminal N-acetyl-D-glucosamine structure.

The specificity of a mouse anti-testicular cell monoclonal antibody, J1, was investigated. Previous studies suggested that N-acetyl-D-glucosamine (GlcNAc) was a constituent of the determinant recognized by J1. When the antibody was tested against a variety of purified glycolipids containing this saccharide in terminal, penultimate or internal positions, J1 reacted only with species expressing terminal GlcNAc. The influence of oligosaccharide chain length, branch substitution, and haptenic valence on J1 binding was examined using glycolipids prepared by a weak acid hydrolysis and exoglycosidase digestion of bovine I-active ganglioside. Degree of binding was inversely proportional to chain length and was proportional to hapten valence. Failure of J1 to bind partially deglycosylated transferrin implied binding preference for GlcNAc beta 1----3Gal over GlcNAc beta 1----2Man. Immunofluorescence analysis of J1 binding to human neutrophils failed to detect lactotriosylceramide on their surface, although this glycolipid has previously been isolated from these cells, suggesting that this structure exists in a cryptic or intracellular form. Binding results were consistent with J1 having low affinity for GlcNAc or GlcNAc beta 1----3Gal on a variety of lacto-series glycolipids.

Acetylglucosamine↗
PubMed1991

Metal binding to heparin monosaccharides: D-glucosamine-6-sulphate, D-glucuronic acid, and L-iduronic acid.

In order to ascertain which residues in heparin may be responsible for its metal binding capacities we have investigated metal binding to some of its component monosaccharides by 1H and 13C NMR. The diamagnetic Zn ion and the paramagnetic Ni ion were used as probes. 4-Methylumbelliferyl-2-deoxy-2-acetamido-6-O-sulpho-D-glucosamine was used as a model for O-sulphates. Only weak interactions with the sulphate group were found. The 4C1 ring conformation of sodium methyl-beta-D-glucopyranosiduronate was not perturbed by binding to its carboxylate and little evidence exists for chelation. By contrast, the ring conformation of the sodium methyl-alpha-L-idopyranosiduronate is affected by the addition of Zn greater than Pb greater than Cd greater than Ca much greater than K ions. The sodium salt is suggested to be an equilibrium mixture of the 2SO and 1C4 ring conformations. Cation binding to the carboxylate group shifts this equilibrium towards the 1C4 conformation and suggests additional binding to O5 or, less likely, O4. This effect appears to be electrostatic in nature, as excess Na and protonation produce similar shifts. Lead complexation is different from the other ions and suggests some covalent character. The control of the ring conformation of iduronic acid by metal ions may have biological implications for the action of heparin and heparin-like compounds.

Cadmium↗
PubMed1984

Synergistic effect of N-acetyl-D-glucosamine (NAG) on mitogenic, antigenic and allogeneic stimulation of normal human lymphocytes.

The effect of N-acetyl-D-glucosamine (NAG) on in vitro stimulated human peripheral blood lymphocytes was investigated. NAG was added to lymphocyte cultures stimulated by the mitogen PHA, the antigen PPD or to one-way-stimulated mixed lymphocyte cultures from unrelated donors. The results indicate that NAG (1-2 micrograms/ml) in appropriate experimental conditions has an enhancing effect on DNA and protein synthesis induced by PHA, PPD and allogeneic cells. Addition of NAG (1-2 micrograms/ml) to unstimulated lymphocyte cultures had no effect on DNA or protein synthesis.

Acetylglucosamine↗
PubMed1989

Enhancement of nonspecific resistance to bacterial infections and tumor regressions by treatment with synthetic lipid A-subunit analogs. Critical role of N- and 3-O-linked acyl groups in 4-O-phosphono-D-glucosamine derivatives.

Enhancement of nonspecific resistance against Pseudomonas aeruginosa infection and regression of growth of Meth A fibrosarcoma by chemically synthesized lipid A-subunit analogs, 4-O-phosphono-D-glucosamine derivatives carrying 3-O- and N-linked acyl groups, were investigated. Compounds carrying an (R)-3-hydroxytetradecanoyl (C14-OH) group at the 2-N-position with (R)-3-tetradecanoyloxytetradecanoyl [C14-O-(C14)] or (R)-3-dodecanoyloxytetradecanoyl [C14-O-(C12)] groups at the 3-O-position, termed GLA-60 or GLA-63, respectively, showed strong activity about one-tenth that of natural lipid A. The protective activity of compounds carrying an (R)-3-hexadecanoyloxytetradecanyl group instead of a C14-O-(C14) or C14-O-(C12) group was very weak. GLA-59 carrying the same acyl components as those of GLA-60 but with reversed binding sites showed significant but not so strong protective activity. The activity of compounds possessing a tetradecanoyl group instead of a C14-OH group in GLA-60 or GLA-63 was weaker than that of GLA-60 or GLA-63. Intravenous or intratumoral administration of GLA-59, GLA-60 and GLA-63 induced significant regression of Meth A fibrosarcoma in terms of tumor size, tumor weight and number of cured mice. The activity of GLA-59 was almost equivalent to that of GLA-60. None of the tested compounds exhibited significant pyrogenicity at a dose of 10 micrograms/kg in rabbits.

Adjuvants, Immunologic↗
PubMed1979

Alaskan malamute chondrodysplasia--VIII. Incorporation of [14C]glucosamine and [3H]serine in hepatic metal-binding proteins of Canis familaris.

1. Hepatic proteins isolated from control kennel dogs bound small quantities of zinc and iron and the peptide fraction contained neither metal. 2. Zince loading of kennel dogs stimulated an hepatic uptake of five times more zinc and three times more iron than an equivalent copper load. The increase in metal concentration was noted in the 10,000 dalton protein. 3. Both the 12,000 and 10,000 dalton proteins isolated from kennel dogs contained more binding sites specific for zinc than for either copper or iron. All three proteins isolated from Alaskan Malamutes showed a smaller affinity for zinc than copper or iron. 4. Both copper and zinc loading stimulated an uptake of [14C]glucosamine and [3H]serine from the peptide fraction of control kennel dogs into the 10,000 dalton protein.

Animals↗
PubMed1990

Isolation, purification, and characterization of glucosamine-6-phosphate-N-acetylase from pig liver.

The procedure of isolation, purification, and characterization of glucosamine-6-phosphate acetylase from the pig liver is described. The steps of purification were as follows: adsorption on hydroxylapatite, fractionation with ammonium sulfate, chromatography on cellulose phosphate, electrofocusing, and preparative gel electrophoresis. A highly purified (about 3000-fold) preparation of GlcN-6-P acetylase, with a yield of 23%, was obtained. It was found that GlcN-6-P acetylase from pig liver is heterogeneous and exists in two active forms. The characteristic features of the preparation were established: Mr, about 24 kDa; temperature optimum at 37 degrees; pH optimum at 7.45; and Km (GlcN-6-P) 3.7 x 10(-3) M and Km (AcCoA) 1.4 x 10(-3) M. The ions K+, Na+, NH4+, Mg2+, Mn2+, and CH3COO- do not stimulate the acetylase activity. The product of acetylase reaction (GlcNAc-6-P) inhibits this reaction according to the feedback process. The highly purified preparation of GlcN-6-P acetylase is unstable during storage and it is protected by ampholine or glycine from enzyme inactivation, but it is not protected by 2-mercaptoethanol.

Acetyltransferases↗
PubMed2004

Monitoring the formation of Maillard reaction products of glucosamine with fibrinogen and human serum albumin using capillary electrophoresis.

Formation of Maillard reaction products (MRP) of glucosamine (GlcN) with fibrinogen and human serum albumin (HSA), under simulated physiological conditions, was detected by fluorescence (excitation/emission: 340/420 nm) and UV/Vis (max. 275 nm) spectroscopy. The application of polyacrylamide gel electrophoresis demonstrated the generation of high-molecular-weight fibrinogen and HSA MRP by GlcN. A simple and rapid capillary electrophoresis method was developed to separate MRP formed by the reaction of GlcN with proteins from GlcN autocondensation products.

Electrophoresis, Capillary↗
PubMed2005

Capillary electrophoretic analysis of advanced glycation endproducts formed from the reaction of reducing sugars with the amino group of glucosamine.

Glucosamine (GlcN) is an amino sugar sold over-the-counter and is widely used as a dietary supplement to relieve symptoms of osteoarthritis. It is not known whether it is the GlcN alone or one of its many possible nonenzymatic glycation products that is responsible for this effect. The current study demonstrates that reducing sugars form advanced glycation endproducts (AGEs) with GlcN and, as a result, decrease GlcN autocondensation by reducing the availability of the GlcN amino group. Capillary electrophoresis (CE) was used to analyze the in vitro Maillard reaction of GlcN with glyceraldehyde (GA), glucose (Glc), and fructose (Fru) as well as their inhibition of GlcN autocondensation under physiological conditions. Formation of AGEs was monitored by UV and fluorescence spectroscopy. Major components were separated by CE using a bare capillary and UV detection at 214 nm. AGE species were separated by HPLC and were complementary to the CE results. The effects of sugar concentration and incubation time on the AGE profile are also reported for each of the GlcN reducing sugar model systems. A simple and rapid CE method was developed to analyze the AGE formation in this initial report of the reaction of reducing sugars with the amino group of GlcN.

Buffers↗
PubMed2005

Glucosamine induces rapid desensitization of glucose transport in isolated adipocytes by increasing GlcN-6-P levels.

We have examined the hypothesis that glucosamine (GlcN) can rapidly induce insulin resistance through an allosteric mechanism. When insulin-treated adipocytes were exposed to 2mM GlcN, glucose uptake was rapidly reduced by approximately 60% with a T(1/2) of 2 min. We also observed an increase in intracellular GlcN-6-P (at 5 min) from undetectable levels to approximately 260 nmol/g. Continued GlcN treatment resulted in additional accumulation of GlcN-6-P (>1200 nmol/g at 2h), but caused no further decrease in glucose uptake. Although the acute inhibitory action of GlcN could be completely reversed by removing extracellular GlcN, a slow and progressive decrease in insulin-stimulated glucose transport was observed with longer treatment times (T(1/2) of 45 min, 62% loss by 5h). From these data, we conclude that: (1) GlcN elevates intracellular GlcN-6-P levels within minutes, resulting in desensitization of the glucose transport system through allosteric inhibition of hexokinase; (2) prolonged treatment elevates GlcN-6-P to levels that cannot be effectively lowered by cell washing; and (3) residual levels of GlcN-6-P continue to allosterically inhibit glucose uptake, resulting in a slower rate of desensitization that is temporally similar to glucose-induced desensitization, but mechanistically different.

Adipocytes↗
PubMed2006

Enhanced chondrogenic differentiation of murine embryonic stem cells in hydrogels with glucosamine.

Differentiation of embryonic stem (ES) cells generally occurs after formation of three-dimensional cell aggregates, known as embryoid bodies (EBs). We have previously reported that hydrogels provide EBs a supportive environment for in vitro chondrogenic differentiation and three dimensional tissue formation [Hwang NS, et al. The Effects of three dimensional culture and growth factors on the chondrogenic differentiation of murine ES cells. Stem Cells 2006;24:284-91]. In this study, we report chondrogenic differentiation of murine ES cells encapsulated in photopolymerizing poly(ethylene-glycol)-based (PEG) hydrogels in the presence of glucosamine (GlcN), an amino monosaccharide found in chitin, glycoproteins and glycosaminoglycans such as hyaluronic acid, chondroitin sulfate and heparin sulfate. We examined the growth and differentiation of encapsulated EBs in standard chondrogenic differentiation medium containing 0-, 2-, and 10-mm GlcN. Morphometric analysis and examination of gene and protein expression indicated that treatment of hydrogel cultures with 2-mm GlcN for 21 days significantly increased EB size, levels of aggrecan mRNA, and tissue-specific extracellular matrix accumulation. GlcN can induce multiple aspects of cell behavior and optimal GlcN concentrations can be beneficial for directing the differentiation and tissue formation of ES cells.

Animals↗