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PubMed1995

Characterization of an acidic polysaccharide isolated from the leaves of Corchorus olitorius (Moroheiya).

An acidic polysaccharide was isolated from the water-soluble mucilage extracted from dried leaves of Corchorus olitorius, known as Moroheiya in Japan (3.0 g per 100 g). This polysaccharide showed a single peak in a Sepharose CL-6B column, and the specific rotation in H2O at 25 degrees C was +250 degrees. The polysaccharide was rich in uronic acid (65%), and consisted of rhamnose, glucose, galacturonic acid, and glucuronic acid in a molar ratio of 1.0:0.2:0.2:0.9:1.7, in addition to 3.7% of the acetyl group. A methylation analysis, Smith degradation study and fragmentation analysis suggested that this polysaccharide mainly consisted of O-4 substituted galacturonic acid and glucuronic acid, and O-2 substituted rhamnose residues, and that most of the (1-->4)-linked uronic acid residues were substituted at the O-3 position with glucuronic acid residues. This polysaccharide showed proliferative activity toward the murine splenocyte.

Animals↗
PubMed1985

Effect of L-ascorbic acid supplementation on the toxicity of pirimiphos-methyl to albino rats.

The effect of L-ascorbic acid supplementation on Pirimiphos-methyl induced toxicity was studied in albino rats. Biochemical estimations were made in rats administered orally the insecticide at 100 and 200 mg/kg body weight with or without oral supplementation of L-ascorbic acid at 200 mg/kg b.w. The biochemical assessments included estimations of brain and plasma cholinesterases, levels of ascorbic acid in liver, kidney and adrenals, urinary levels of ascorbic acid and glucuronic acid. A lower degree of inhibition of the cholinesterases were evident in ascorbic acid supplemented rats. Marked elevation in urinary levels of ascorbic acid and glucuronic acid was observed in the insecticide treated rats. Results of this study suggests that L-ascorbic acid supplementation partially offsets Pirimiphos-methyl induced toxicity.

Acetylcholinesterase↗
PubMed1992

Functional reconstitution of the lysosomal sialic acid carrier into proteoliposomes.

The lysosomal carrier for the acidic monosaccharides sialic acid and glucuronic acid was solubilized from rat liver lysosomal membranes and reconstituted into phospholipid vesicles. Membrane proteins were extracted from lysosomal membranes with Triton X-100. Upon removal of the detergent by absorption on Amberlite XAD-2 beads, the solubilized proteins were incorporated in egg yolk phospholipids. The reconstituted proteoliposomes show proton-driven carrier-mediated uptake of acidic monosaccharides. The reconstituted carrier was compared in several characteristics with the transporter as present in the native lysosomal membrane. Transporter substrate affinity (Kt for glucuronic acid = 0.4 mM) and specificity for acidic monosaccharides are completely retained. The proteoliposomes also demonstrate trans-stimulation properties with both substrates sialic acid and glucuronic acid. The transporter is inhibited, both in its native and in the reconstituted state, by the sulfhydryl-modifying agents p-chloromercuribenzoic acid, N-ethylmaleimide, and phenyl isothiocyanate. In native membrane vesicles, arginine and histidine modifiers phenylglyoxal and diethyl pyrocarbonate inactivated transport in a substrate-protectable manner. In reconstituted proteoliposomes, similar inhibition was observed. However, protection by substrates was achieved only after treatment with phenylglyoxal. These data suggest that arginine or histidine residues or both are present at or near the substrate binding site of the carrier. Possibly, other essential histidines become exposed in the reconstituted state. The successful functional reconstitution of the lysosomal sialic acid carrier represents an important step towards its purification and its detailed molecular characterization.

Animals↗
PubMed1981

A kinetic mechanism for modulation of the activity of microsomal UDP-glucuronyltransferase by phospholipids. Effects of lysophosphatidylcholines.

The affinity of delipidated microsomal UDP-glucuronyltransferase (EC 2.3.1.17) for UDP is greater than that for UDP-glucuronic acid. Measurement of KIglucuronic acid reveals that glucuronic acid binds to the enzyme. Hence, the difference in affinity of the enzyme for UDP versus UDP-glucuronic acid indicates that inherent binding energy for interactions between enzyme and this substrate is used for purposes other than enhancing binding. A reasonable interpretation of these data is that the binding of UDP-glucuronic acid to enzyme requires distortion of the substrate and/or the enzyme. Inherent binding energy due to interactions between enzyme and UDP and glucuronic acid is utilized to effect such distortions. This type of mechanism can cause significant rate enhancement. Phospholipid activators of UDP-glucuronyltransferase activate by amplifying this basic mechanism. Thus, addition of various species of lysophosphatidylcholine to the delipidated enzyme increase the activity at Vmax and enhance the affinity for UDP, glucuronic acid, and UDP-glucuronic acid. However, activators enhance the affinity of the enzyme for UDP-glucuronic acid to a significantly smaller extent than they enhance affinity for the UDP and glucuronic acid portions of the substrate. Calculations of the amount of binding energy for interactions between enzyme and UDP-glucuronic acid that can be used for stimulating activities at Vmax yield values in agreement with the observed enhancement of activities at Vmax for enzyme reconstituted with various types of lysophosphatidylcholine.

Animals↗
PubMed1975

Fragmentation analysis of extracellular acid polysaccharides from seven Rhizobium strains. Part I. D-glucuronic acid-containing oligosaccharides.

The extracellular, bacterial polysaccharides from seven Rhizobium strains have been submitted to partial hydrolysis with acid. Several neutral oligosaccharides, some containing pyruvic acid, were isolated together with D-glucuronic acid-containing oligosaccharides. The polysaccharide from Rh. meliloti did not contain glucuronic acid. For the other six strains, the following components were characterized: 4-O-(beta-D-glucopyranosyluronic acid)-D-glucuronic acid, 4-O-(beta-D-glucopyranosyluronic acid)-D-glucose, and O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-D-glucose. These results indicate the presence of chains containing two beta-(1leads to4)-linked D-glucuronic acid residues, beta-linked to D-glucose at position 4.

Glucose↗
PubMed1999

Production of a novel exopolysaccharide by Rahnella aquatilis.

A bacterium Tomakomai B-1 that was isolated from the activated sludge of a treatment process for wastewater of the pulp industry was found to produce soluble and insoluble exopolysaccharides (EPSs) when grown aerobically in a medium containing sucrose as the sole carbon source. The sugar component of soluble EPSs consisted of rhamnose, mannose, galactose, glucose, mannuronic acid, galacturonic acid and glucuronic acid, and that of insoluble EPSs consisted of rhamnose, mannose, galactose, glucose, mannuronic acid and glucuronic acid. The concentrations of insoluble and soluble EPS were approximately 1.63 and 2.58 g/l, respectively, by Erlenmeyer flask culture at 20 degrees C for 3 d with a synthetic medium containing 1% sucrose, 0.05% CaCO(3), 0.05% MgSO(4), 0.1% K(2)HPO(4), 0.0001% Na(2)MoO(4), 0.01% urea, 1.07% MES and small amounts of trace metals. Tomakomai B-1 was identified as Rahnella aquatilis. To our knowledge the production of EPSs by R. Aquatilis is reported here for the first time.

Journal Article↗
PubMed1988

Comparison of salicylamide and acetaminophen and their prodrug disposition in dogs.

Comparative studies on the disposition of two pairs of drugs and their prodrugs, i.e., (1) salicylamide (SAM) and ethenzamide (ETB), (2) acetaminophen (NAPA) and phenacetin (PHT), were performed in dogs following intravenous and oral administration of the drugs. ETB and PHT were largely metabolized to SAM and NAPA, respectively, and SAM and NAPA thus formed or those directly administered were conjugated with sulfuric acid and glucuronic acid. It was found that the prodrugs, ETB and PHT, were more susceptible to first-pass metabolism than the corresponding parent drugs, SAM and NAPA, respectively at 30 mg/kg dose of each drug. Free NAPA levels in the blood of dogs receiving PHT were found to be considerably high, whereas free SAM levels in the blood of dogs receiving ETB were very low. These are consistent with results in humans which have been reported earlier, suggesting the similarity between dogs and humans. The ratio of sulfate to the sum of sulfate and glucuronide (S-ratio) as the area under blood concentration-time curve and urine were examined. The prodrugs (ETB and PHT) showed higher S-ratios than the corresponding parent drugs (SAM and NAPA). The S-ratios were greater than 0.6 in ETB and SAM and less than 0.5 in PHT and NAPA, indicating that sulfate formation was predominant in the former pair while glucuronide formation was predominant in the latter pair. No intestinal metabolism was found in the prodrugs. In the parent drugs, however, conjugation with sulfuric acid and glucuronic acid was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen↗
PubMed1983

Glucuronic acid-containing glycopeptide from squid cartilage.

A glycopeptide fraction containing glucuronic acid as a component sugar was extracted and purified from squid cartilage to give a single band migrating much slower than hyaluronic acid in cellulose acetate electrophoresis. The molecular weight of the glycopeptide was fairly large since its Kav value in Sephadex G-200 chromatography was 0.18; however, it was soluble in 66% ethanol. This glycopeptide contained glucuronic acid, glucosamine, galactosamine, galactose, and fucose. The total amino acid content was 1.87 mumol of amino acid per mg of the glycopeptide. Threonine, serine and proline represented 80% of the amino acids. Digestion with chondroitinase ABC or reaction with nitrous acid did not result in degradation of the glycopeptide; however, it was completely degraded by reaction with 0.5 M KOH at 37 degrees C. Two hexasaccharides were separated from the alkaline degradation products, and they both contained glucuronic acid, fucose, galactosamine, and reducing terminal glucosamine in the molar ratio, 2:1:2:1. These results indicated that the glycopeptide contains glucuronic acid-containing sugar chains that are distinct from any known glycosaminoglycan.

Amino Acids↗
PubMed1976

Pyrophosphatase and glucuronosyltransferase in microsomal UDPglucuronic-acid metabolism in the rat liver.

1. A radiochemical method for the studies on the microsomal UDPglucuronic acid metabolism has been developed. 2. The rat liver microsomes caused a rapid hydrolysis of UDPglucuronic acid to D-glucuronic acid 1-phosphate and further although much slower to free D-glucuronic acid. In Tris-HCl buffer (pH 7.4) they were produced in ratio 72 : 1. No other metabolites were found in measurable amounts. The pyrophosphatase splitting UDPglucuronic acid showed a pH optimum at 8.9, but the liberation of D-glucuronic acid from UDPglucuronic acid had two pH maxima (pH 3.5 and 8.5). EDTA appeared to be less powerful inhibitor of pyrophosphatase than previously suggested. About 25 per cent of the UDPglucuronic acid hydrolyzing activity was still remaining in the presence of 10 mM EDTA. D-Glucaro-1,4-lactone was found to have a slight inhibitory action on the pyrophosphatase activity. Citrate inhibited powerfully the hydrolysis of UDPglucuronic acid and the liberation of free D-glucuronic acid. Phosphate was also inhibitory. 3. In the presence of an exogenous UDPglucuronosyltransferase substrate, 4-nitrophenol, the formation of D-glucuronic acid 1-phosphate and free D-glucuronic acid were slightly reduced, and D-glucuronic acid 1-phosphate, 4-nitrophenylglucuronide and free D-glucuronic acid were produced in ratio 78 : 23 : 1. When 10 mM EDTA was added to diminish the hydrolytic consumption of the glucuronyl donor substrate, the corresponding ratio was still as unfavorable as 19 : 2.6 : 1. The measurable activity of UDPglucuronosyltransferase was lower in the presence of phosphate or citrate than in Tris-HCl buffer, although they protected the glucuronyl donor substrate against hydrolysis. 4. The results indicate that even in the presence of added glucuronyl acceptor substrate the hydrolysis of UDPglucuronic acid predominates the conjugation in rat liver microsomes. The rate of the hydrolysis of UDPglucuronic acid is quite considerable even in the presence of EDTA, and it is recommended to control the UDPglucuronic acid pyrophosphatase activity when UDPglucuronosyltransferase and glucuronidation reactions are studied. Free D-glucuronic acid appears to be produced from UDPglucuronic acid for further use via D-glucuronic acid 1-phosphate, the rate-limiting step being the hydrolysis of this intermediate. UDP-glucuronosyltransferase, glucuronides of either endogenous or exogenous aglycones and beta-glucuronidase have only a minor role in this respect in rat liver microsomes.

Animals↗
PubMed1999

A synthetic heparan sulfate pentasaccharide, exclusively containing L-iduronic acid, displays higher affinity for FGF-2 than its D-glucuronic acid-containing isomers.

It has been suggested that the FGF-2 binding site on heparan sulfate chains is a trisulfated pentasaccharide containing three hexuronic acid units. The configuration at C-5 of two of them being undetermined, we have synthesized the four possible pentasaccharides, and have evaluated their FGF-2 binding affinity through in vitro biological assays. The pentasaccharide containing L-iduronic acid as the sole hexuronic acid showed higher affinity for FGF-2 than the other pentasaccharides, where one hexuronic acid unit at least is D-glucuronic acid.

Aorta↗
PubMed1980

Isolation and characterization of proteodermatansulfate from rat skin.

A proteodermatansulfate was extracted from rat skin with 4 M guanidine hydrochloride containing protease inhibitors at 4 degrees C. It was separated from collagen on DEAE-cellulose in 7 M urea and was purified by cesium chloride density gradient centrifugation under associative conditions, DEAE-Sephadex column chromatography and then Sephadex G-200 gel filtration. On SDS-disc electrophoresis, the proteoglycan gave a single band staining for protein and a band of the same mobility staining with periodate-Schiff reagent. The proteoglycan contained 46% protein, and this was bound to dermatansulfate via an O-glycosidic linkage. The proteoglycan also contained 20% uronic acid and 16% hexosamine, but no detectable hydroxyproline. The ratio of galactosamine to glucosamine was 68. The dermatansulfate, the only glycosaminoglycan, had a hybrid structure containing iduronic acid and glucuronic acid as uronic acids. The content of glucuronic acid in uronic acid was much higher than that of pig skin dermatansulfate. The dermatansulfate had a slightly higher mobility on cellulose acetate electrophoresis than those from other sources. Gel chromatography on Sepharose CL-6B showed that the molecular weight of the dermatansulfate was 23,000, while that of the proteoglycan was 36,000. The elution profile of a mixture of the proteoglycan and hyaluronic acid on Sepharose 6B column chromatography was similar to that of the proteoglycan alone.

Animals↗
PubMed1990

Use of water-soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide for the fluorescent determination of uronic acids and carboxylic acids.

Reaction between glucuronic acid and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was monitored by the o-phthalaldehyde (OPA) method, which was developed for the fluorescent assay of compounds containing an amino group. About 1 nmol of glucuronic acid was detected by this method. This EDC-OPA method was effective in detecting not only acidic sugar but also carboxylic acid. Although the sensitivity of the EDC-OPA method was somewhat lower than that of amino acid determination by OPA, a very simple and convenient assay was attained for compounds containing a carboxyl group.

Carbohydrates↗
PubMed1975

Metabolism of uronic acids in plant tissues: partial purification and properties of uronic Acid oxidase from citrus leaves.

A new enzyme, named uronic acid oxidase, was extracted and purified 67-fold by (NH(4))(2)SO(4) fractionation and CM-Sephadex column chromatography from ethylene-treated Shamouti orange (Citrus sinensis L. Osbeck) leaves. The enzyme catalyzes the oxidation of d-galacturonic acid and d-glucuronic acid to the corresponding hexaric acids in the presence of molecular oxygen with the production of H(2)O(2). The pH optimum for the oxidation of d-galacturonic acid and d-glucuronic acid is between 7 and 8. The enzyme is highly specific for d-galacturonic acid and d-glucuronic acid. It also oxidizes polygalacturonic acid. The apparent Michaelis constant values of the enzyme for d-galacturonic acid and d-glucuronic acid are 0.13 and 0.5 mm, respectively. The molecular weight of the enzyme, as determined by gel filtration, is about 98,000. The enzyme is inhibited by sodium hydrosulfite and other sulfites, indicating that it contains a flavin prosthetic group.

Journal Article↗
PubMed1996

Glucuronic acid-conjugated dihydroxy fatty acids in the urine of patients with generalized peroxisomal disorders.

Urine extracts from children diagnosed with generalized peroxisomal disorders were screened by continuous flow-negative ion fast atom bombardment-mass spectrometry. In 45 of 60 children with generalized peroxisomal disorders, we observed one or more intense ions (m/z 489, 505, 461, and others) that are infrequently found in children with cholestatic liver disease or normal children. Compounds giving rise to these ions were isolated using reverse phase and anion exchange chromatography. After appropriate derivatization and/or methanolysis the compounds were analyzed using capillary gas chromatography-mass spectrometry. The major compounds were found to be 12,13-dihydroxy-9-octadecenoic acid and 9,10-dihydroxy-12-octadecenoic acid, with one of the hydroxyl groups in glycosidic linkage with glucuronic acid. Minor compounds were glucuronic acid conjugates of 9,10-dihydroxy-octadecanoic acid, and 12,13-dihydroxy-6,9-, 15,16-dihydroxy-9,12-, and 9, 10-dihydroxy-12,15-octadecadienoic acids. A series of hexadecanoic, hexadecenoic, and hexadecadienoic acid glucuronides which appear to be beta-oxidation products of the C18 fatty acids were also observed, with the major species being 10, 11-dihydroxy-7-hexadecenoic acid glucuronide. In all, 16 C16 and C18 dihydroxy fatty acids were identified by gas chromatography-mass spectrometry. A series of at least 11 trihydroxy fatty acids was also observed but not fully characterized. Measurement of these compounds may prove to be useful in the diagnosis of some peroxisomal disorders.

Child↗
PubMed1970

Some structural features of the teichuronic acid of Bacillus licheniformis N.C.T.C. 6346 cell walls.

A teichuronic acid, containing glucuronic acid and N-acetylgalactosamine, was purified from acid extracts of Bacillus licheniformis 6346 cell walls as described by Janczura, Perkins & Rogers (1961). After reduction of the carboxyl function of glucuronic acid residues in the polysaccharide the reduced polymer contains equimolar amounts of N-acetylgalactosamine and glucose. Methylation of the reduced polysaccharide by the Hakamori (1964) technique showed the glucose residues to be substituted on C-4. A disaccharide, 3-O-glucuronosylgalactosamine, was isolated from partial acid hydrolysates of teichuronic acid. After N-acetylation the disaccharide produces chromogen readily on heating at pH7, in agreement with C-3 substitution of the reducing N-acetylamino sugar. Teichuronic acid also produces chromogen under the same conditions, with concurrent elimination of a modified polysaccharide from C-3 of reducing terminal N-acetylgalactosamine residues of the teichuronic acid chains. The number-average chain lengths of several preparations of teichuronic acid were estimated from the amounts of chromogen produced in comparison with the N-acetylated disaccharide. The values obtained are in good agreement with the weight-average molecular weight determined by ultracentrifugal analysis. The reducing terminals of teichuronic acid are shown to be exclusively N-acetylgalactosamine by reduction with sodium boro[(3)H]hydride. The number-average chain lengths of the teichuronic acid preparations were estimated by the extent of in corporation of tritium and are in agreement with values obtained by the other methods.

Bacillus↗
PubMed1992

A novel glucuronyltransferase in nervous system presumably associated with the biosynthesis of HNK-1 carbohydrate epitope on glycoproteins.

Recently, embryonic chicken brain extract was shown to contain a glucuronyltransferase, which transfers glucuronic acid from UDP-glucuronic acid to glycolipid acceptors (neolactotetraosyl ceramide). The enzyme was also suggested to transfer glucuronic acid to glycoprotein acceptors (asialoorosomucoid) (Das, K. K., Basu, M., Basu, S., Chou, D. K. H., and Jungalwala, F. B. (1991) J. Biol. Chem. 266, 5238-5243). In this study, the glucuronyltransferase activity in rat brain extract was separated into two groups by UDP-glucuronic acid-Sepharose CL-6B column chromatography. The enzyme recovered predominantly in the effluent fraction (GlcAT-L) catalyzed the transfer of glucuronic acid to glycolipid acceptors but not to glycoprotein acceptors, whereas the enzyme recovered in the eluate fraction (GlcAT-P) transferred glucuronic acid most predominantly to glycoprotein acceptors and very little to glycolipid acceptors. GlcAT-P was able to transfer glucuronic acid to oligosaccharide chains on asialoorosomucoid. The enzyme recognized a terminal lactosamine structure, Gal beta 1-4GlcNAc, on glycoproteins. It was localized in the nervous system and was hardly detectable in other tissues, including the thymus, spleen, lung, kidney, and liver. Although GlcAT-L and GlcAT-P shared some properties in common such as tissue distributions and developmental changes, they exhibited marked differences in their phospholipid dependence and in their pH profiles, apart from their respective acceptor preference to glycolipids and glycoproteins. The acceptor specificity and tissue distribution suggest that a novel glucuronyltransferase, GlcAT-P, is involved in the biosynthesis of the sulfoglucuronylgalactose structure in the HNK-1 carbohydrate epitope that is expressed on glycoproteins.

Animals↗
PubMed1996

A comparative study of precision cut liver slices, hepatocytes, and liver microsomes from the Wistar rat using metronidazole as a model substance.

1. Metronidazole is metabolized by rat liver in vitro models to form a hydroxy metabolite, an acetic acid metabolite, a glucuronic acid conjugate, and a sulphate conjugate. 2. Four different in vitro systems for investigation of drug metabolism based on liver preparations from the male Wistar rat have been investigated. 3. An incubation system where liver slices are incubated in 12-well culture plates was evaluated with respect to metabolism of metronidazole. Optimal viability was observed for a time period of up to 24 h. The Michaelis-Menten parameters for the metabolism of metronidazole in liver slices were calculated and the intrinsic clearance values compared with the values determined in hepatocytes incubated in suspension. It was found that the intrinsic clearance with respect to formation of oxidative metabolites, the hydroxy metabolite, and the acetic acid metabolite correlated, whereas the intrinsic clearance with respect to formation of the glucuronic acid conjugate was lower in slices compared with hepatocytes. 4. The metabolism of metronidazole in liver slices, in hepatocytes in primary monolayer culture, in hepatocytes incubated in suspension, and in liver microsomes was compared. All the incubations were performed under identical incubation conditions including the same incubation medium. The trend observed was that the initial metabolic rates of the production of the hydroxy metabolite, the glucuronic acid metabolite, and the acetic acid metabolite of metronidazole were higher in microsomes than in the other liver preparations. The metabolic rates in hepatocytes in primary culture and in suspension with respect to the oxidative metabolites were higher than in liver slices. The metabolic turnover observed in liver slices was predicted to correlate with in vivo data earlier obtained for rat.

Acetic Acid↗