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Simultaneous, quantitative analysis of UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine, UDP-glucose and UDP-galactose in human peripheral blood cells, muscle biopsies and cultured mesangial cells by capillary zone electrophoresis.

The aim of this study was to develop and evaluate a capillary zone electrophoretic (CE) procedure for the accurate quantification of the UDP-hexosamines as well as for the corresponding UDP-hexoses in samples from various biological origins. Testing different buffer conditions, voltages, capillary dimensions and temperatures, optimal results were achieved with a 90 mM borate buffer, pH 9.0, at 18 degrees C and 15.5 kV in an uncoated fused-silica capillary of 50 cm x 50 microm and a detection wavelength of lambda = 262 nm. The total procedure, i.e., including variations of the sample preparatio

Carbohydrate metabolism and the glucoreceptor mechanism.

Current views on the recognition of sugars as signals for insulin biosynthesis and release are discussed. Evidence is presented that the initial steps in the metabolism of N-acetyl-glucosamine differ from those in glucose metabolism in that for the former transport into the islet represents the rate-limiting step. Different enzymes phosphorylate these two sugar, but it is suggested that N-acetylglucosamine and glucose enter the beta-cell via the same carrier since 3-O-methylglucose is shown to be a competitive inhibitor of N-acetylglucosamine oxidation. Inhibitory effects on N-acetylglucosamin…

Tay-Sachs disease with hexosaminidase A: characterization of the defective enzyme in two patients.

Cases of infantile Tay-Sachs disease (TSD) with high residual hexosaminidase A (Hex A) activity have recently been described. The clinical presentation of the disease in these patients is identical to that found among Ashkenazi-Jewish patients. Fibroblasts from two such TSD patients had Hex A activity comprising 16% of total Hex when measured by thermal fractionation and quantitation with 4-methylumbelliferyl-beta-D-N-acetylglucosamine (4MUG). Hydrolysis of 4-methylumbelliferyl-beta-D-N-acetylglucosamine-6-SO4 (4MUGS) by patient fibroblast extracts is catalyzed by an enzyme activity that compr…

Identification and Characterization of EmNag, a Novel β-1,2-N-Acetylglucosaminidase from Elizabethkingia meningoseptica.

N-Acetylglucosamine exists in various glycoforms and linkage patterns within organisms, playing a crucial role in numerous vital biological processes. The signal of β-1,2-N-acetylglucosamine is a key component within complex biantennary N-glycans on the cell surface, leaving related research in its early exploratory stages. Currently, there is a lack of efficient tools and methods capable of directly modifying terminal N-acetylglucosamine on living cells. In this study, we identified a novel β-N-acetylglucosaminidase from Elizabethkingia meningoseptica FMS-007, which specifically cleaves nonre…

UDP-GlcNAc 2-Epimerase/ManNAc Kinase (GNE): A Master Regulator of Sialic Acid Synthesis.

UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase is the key enzyme of sialic acid biosynthesis in vertebrates. It catalyzes the first two steps of the cytosolic formation of CMP-N-acetylneuraminic acid from UDP-N-acetylglucosamine. In this review we give an overview of structure, biochemistry, and genetics of the bifunctional enzyme and its complex regulation. Furthermore, we will focus on diseases related to UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase.

Sialic acid deficiency in lectin-resistant intestinal brush border membranes from rats following the intestinal phase of trichinellosis.

Maximal binding (Bmax) of the lectin, wheat germ agglutinin, by small intestinal brush border membrane is significantly reduced in rats infected with Trichinella spiralis. Wheat germ agglutinin specificity is for N-acetylglucosamine and sialic acid. Whereas total hexosamine and N-acetylglucosaminidase-labile N-acetylglucosamine were comparable in membranes from uninfected as compared with infected rats, the total sialic acid content and neuraminidase-released sialic acid were significantly higher in BBM from uninfected hosts. N-Acetylglucosaminidase treatment of membranes reduced Bmax for whea…

A fluorimetric enzyme assay for the diagnosis of Sanfilippo disease type D (MPS IIID).

4-Methylumbelliferyl-alpha-N-acetylglucosamine 6-sulphate was synthesized and shown to be a substrate for the lysosomal N-acetylglucosamine-6-sulphate sulphatase (GlcNAc-6S sulphatase). Fibroblasts and leukocytes from 3 different Sanfilippo D patients showed < 1% of mean normal GlcNAc-6S sulphatase activity. The enzymatic liberation of the fluorochrome from 4-methyl-umbelliferyl-alpha-N-acetylglucosamine 6-sulphate requires the sequential action of the GlcNAc-6S sulphatase and alpha-N-acetylglucosaminidase. A normal level of alpha-N-acetylglucosaminidase activity was insufficient to complete t…

Osteoarthritis as a marker and potential contributor to cardiovascular risk: a glycocalyx-cartilage axis hypothesis.

Osteoarthritis (OA) may be more than simply a reflection of aging; it could represent a symptom of underlying vascular disease processes with serious consequences for health and quality of life. The association of OA with other conditions like cardiovascular disease (CVD) suggests OA may be partially systemic and metabolic in nature. As such, this connection underscores the value of exploring the biochemical parallels between articular joints and the endothelial glycocalyx, the protective lining of blood vessels. N-acetylglucosamine may be central to this link because both articular cartilage …

Examination of sialic acid binding on dystrophic and normal retinal pigment epithelium.

In order to study differences in cell-surface sugars which may be involved in the phagocytic defect in Royal College of Surgeons (RCS) retinas, we have examined the presence or absence of lectin binding to carbohydrates on retinal pigment epithelial (RPE) plasma membranes of dystrophic (RCS-p+) and normal (Long-Evans) rats. A lectin which binds to both sialic acid and N-acetylglucosamine sugar residues, wheat germ agglutinin-ferritin (WGA-fe), was used. The specificity of WGA-fe binding to each sugar was studied by either pre-treating the tissue with neuraminidase enzyme which removes sialic a…

Incorporation of Novel Synthetic Glycolipids in Liposomal Nanoparticles Affects Opsonization and In Vivo Clearance.

Mimicking cell membrane glycocalyx, saccharide modification of nanoparticles offers a potent means to regulate their in vivo fate. Here, we investigate how glycosylation (i.e., glucose, galactose, fructose, mannose, and N-acetylglucosamine) regulates liposomal nanoparticle interactions with plasma proteins and immune cells, which further determine their biodistribution and therapeutic efficacy. While fructose conferred the greatest enhancement in tumor cell uptake in vitro, N-acetylglucosamine-modified nanoparticles achieved the highest tumor accumulation and markedly attenuated systemic clear…

Sanfilippo syndrome, type D: a spectrophotometric assay with prenatal diagnostic potential.

Sanfilippo syndrome, type D (MPS IIID), is characterized by moderate physical abnormalities, progressive mental deterioration, and deficient activity of N-acetylglucosamine 6-sulfate sulfatase, a lysosomal hydrolase involved in the degradation of heparin, keratan sulfate, and heparan sulfate. To date, demonstration of the enzyme deficiency typically relies on a radiolabeled trisaccharide substrate derived from heparan sulfate. In our study, we have developed a spectrophotometric assay for the determination of N-acetylglucosamine 6-sulfate sulfatase activity using the monosaccharide, N-acetylgl…

Hexokinase isoenzymes in normal and cirrhotic human liver: suppression of glucokinase in cirrhosis.

The activities of hexokinase isoenzymes I-IV (EC 2.7.1.1) and of N-acetylglucosamine kinase (EC 2.7.1.59) were determined in normal human liver and in alcoholic liver disease and primary biliary cirrhosis after FPLC fractionation of high-speed supernatants on Mono-Q with a linear NaCl gradient. In control human liver the hexokinase activities were: I, 3.6; II, 0.7; III, 3.5, IV, 4.8 (mUnits/mg supernatant protein). The activity of N-acetylglucosamine kinase was 8 mU/mg of protein. In alcoholic liver disease and primary biliary cirrhosis, the activity of hexokinase IV (glucokinase) was suppress…

Utilization of exogenously added acetyl coenzyme A by intact isolated lysosomes.

Acetyl coenzyme A has been shown to be required for heparan sulfate degradation for the acetylation of terminal alpha-linked glucosamine res … eparan sulfate and the radioactivity was shown to be located in acetyl moieties of terminal alpha-N-acetylglucosamine residues. The acetylation of heparan sulfate in alpha-N-acetylglucosaminidase-deficient lysosomes could be stimulated by the addition of 0.5 mM ATP. Lysosomes from normal cells produced some labeled heparan sulfate; however, these organelles showed …

Deficiencies of glucosamine-6-sulfate or galactosamine-6-sulfate sulfatases are responsible for different mucopolysaccharidoses.

[1-3H]Galactitol-6-sulfate, N- [1-3H]acetylgalactosaminitol-6-sulfate, N-[1-3H]acetylglucosaminitol-6-sulfate, N-acetylglucosamine-6-sulfate, and 6-sulfated tetrasaccharides from chondroitin-6-sulfate have been used for the measurement of 6-sulfatase activity of extracts of normal skin fibroblasts and of fibroblasts cultured from patients with genetic mucopolysaccharidoses. With these substrates, extracts of fibroblasts derived from Morquio patients lack or have greatly reduced activities for galactitol-6-sulfate, N-acetylgalactosaminitol-6-sulfate, and 6-sulfated tetrasaccharides but have nor…

Further studies on the glycerol teichoic acid of walls of Staphylococcus lactis I3. Location of the phosphodiester groups and their susceptibility to hydrolysis with alkali.

1. The teichoic acid from walls of Staphylococcus lactis I3 is readily degraded in dilute alkali. 2. Degradation proceeds by selective hydrolysis of that phosphodiester group attached to an alcoholic hydroxyl group of the N-acetylglucosamine and gives a repeating unit in high yield. 3. Further studies on a different repeating unit isolated by partial acid hydrolysis have shown that the glycerol diphosphate is attached to the 4-hydroxyl group of the N-acetylglucosamine and not to the 3-hydroxyl group as was proposed earlier. 4. The susceptibility towards hydrolysis by alkali of other structural…

O-GlcNacilation: молекулярный переключатель, связывающий здоровье мозга с нейродегенерацией.

Нейродегенеративные расстройства, как правило, вызваны вредным накоплением белков и повреждением нервных клеток. Послепереходная модификация, называемая N-ацетилглюкозаминовой илляцией, действует как критический регулятор в этих расстройствах, контролируя поведение белков, сигнализацию клеток и энергетический баланс. Эта модификация динамическо сбалансирована благодаря совместным действиям связанных с O переносчиков N-ацетилглюкозамина и O-GlCNAace. В здоровых мозгах O-GlcNacilation поддерживает функцию нервных клеток и выживание, но их дисбаланс способствует прогрессированию заболеваний. В ча

Совпадение в аннотации оригинала
Neurodegenerative disorders are typically caused by harmful protein accumulation and nerve cell damage. A post-translational modification called O-linked N-acetylglucosamine ylation acts as a critical regulator in these disorders by controlling protein behavior, cell signaling, and energy balance. This modification is dynamically balanced through the coopera…

Host glycan sugar-specific pathways in Streptococcus pneumoniae: galactose as a key sugar in colonisation and infection [corrected].

The human pathogen Streptococcus pneumoniae is a strictly fermentative organism that relies on glycolytic metabolism to obtain energy. In th … enes likely to be involved in deglycosylation, transport and catabolism of galactose, mannose and N acetylglucosamine. In contrast to growth on mannose and N-acetylglucosamine, S. pneumoniae grown on galactose re-route their metabolic pathway from homolactic fermentation to a truly mixed acid fermentation regime. By measuring intracellular metabolites, enzymatic ac …

Succinylated Wheat Germ Agglutinin Colocalizes with the Toxoplasma gondii Cyst Wall Glycoprotein CST1.

The glycosylated mucin domain of the Toxoplasma gondii cyst wall glycoprotein CST1 is heavily stained by Dolichos biflorus agglutinin, a lectin that binds to N-acetylgalactosamine. The cyst wall is also heavily stained by the chitin binding lectin succinylated wheat germ agglutinin (s-WGA), which selectively binds to N-acetylglucosamine-decorated structures. Here, we tracked the localization of N-acetylglucosamine-decorated structures that bind to s-WGA in immature and mature in vitro cysts. s-WGA localization was observed at the cyst periphery 6 h after the differentiation of the tachyzoite-s…

GLUL mediates FOXO3 O-GlcNAcylation to regulate the osteogenic differentiation of BMSCs and senile osteoporosis.

The abnormal osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is an important cause of senile osteoporosis (SOP). Gl … tite Motif Containing 25 (TRIM25) SPRY subunit, reduced the ubiquitin-mediated degradation of UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1) and increased the synthesis of uridine 5-diphosphate N-acetylglucosamine (UDP-GlcNAc), thereby regulating the O-linked β-N-acetylglucosamine modification (O-GlcNAcylation) of serine 296 residues and increasing Forkhead Box …

An examination of the inhibitory effects of N-iodoacetylglucosamine on Escherichia coli and isolation of resistant mutants.

1. After incubation of Escherichia coli with N-iodo[1,2-(14)C(2)]acetylglucosamine, 95-99% of the (14)C taken up by whole cells is located in a cold-trichloroacetic acid-soluble fraction. Two major components of this fraction are S-carboxymethylcysteine and S-carboxymethylglutathione. The same compounds accumulate during incubation with iodo[(14)C]acetate but not with iodo[(14)C]acetamide. The amount of (14)C associated with a cold-trichloroacetic acid-insoluble fraction are comparable for all three alkylating agents. After incubation with iodo[(14)C]acetamide, 50% of the label bound to whole …