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PubMed1982

Glucose transport in Streptococcus salivarius. Evidence for the presence of a distinct phosphoenolpyruvate: glucose phosphotransferase system which catalyses the phosphorylation of alpha-methyl glucoside.

A spontaneous mutant of Streptococcus salivarius ATCC 25975 was isolated by inoculating an agar medium containing 11 mM lactose and 0.5 mM 2-deoxyglucose. This mutant grew poorly on 5 mM glucose but almost as well as the parental strain on 110 mM glucose. Uptake of 2-deoxyglucose was abolished by the mutation, and phosphoenolpyruvate: glucose phosphotransferase activity could not be detected with toluenized cells under normal conditions when the glucose concentration was below 5 mM. Data from growth experiments, glycolysis, and uptake studies indicated the presence of a second phosphoenolpyruvate: glucose phosphotransferase system that could catalyze the phosphorylation of alpha-methyl glucoside. The activity of this system was detected by a spectrophotometric assay coupled with lactate dehydrogenase and by a radioactive isotope method using methyl alpha-D-[U-14C] glucoside. The phosphorylation was phosphoenolpyruvate dependent. The apparent Km of the system for glucose and alpha-methyl glucoside was approximately 20 mM. Studies with energy poisons ruled out the possibility of an active transport system, and accumulation of alpha-methyl glucoside argued against facilitated diffusion. It was concluded that the other glucose transport system which allowed growth of the mutant strain of S. salivarius was a second phosphoenolpyruvate: glucose phosphotransferase system.

Biological Transport↗

PubMed2000

Hydrolysis of beta-glucosyl ester linkage of p-hydroxybenzoyl beta-D-glucose, a chemically synthesized glucoside, by beta-glucosidases.

To investigate the hydrolysis of glucosyl esters by beta-glucosidase, p-hydroxybenzoyl beta-D-glucose (pHBG) was chemically synthesized. The hydrolytic activity of some beta-glucosidases for pHBG was compared to that for p-nitrophenyl beta-glucoside (pNPG). The Clavibacter michiganense and Flavobacterium johnsonae enzymes could hydrolyze pHBG and steviol glycosides which are natural glucosyl esters. The commercial beta-glucosidase originating from Caldocellum saccharolyticum also hydrolyzes pHBG despite having no activity for steviol glycosides. The beta-glucosidase from Aspergillus niger cleaved the glucosyl ester linkage much more weakly than the glucosidic linkage. The pH-activity profile for the hydrolysis of pHBG was similar to that of pNPG by the C. saccharolyticum beta-glucosidase. The similar profiles for these substrates suggested that the active site for the glucosyl ester chemically resembles that for glucoside with respect to catalysis. Kinetic analysis of the C. saccharolyticum beta-glucosidase for mixed substrates of pHBG and pNPG showed that the hydrolysis of pHBG competed with that of pNPG. This result indicated that there is only one active site for both the glucosyl ester and glucoside. Mass spectroscopic analysis of the hydrolysates of pHBG in H218O suggested that beta-glucosidase hydrolyzes glucosyl esters between the anomeric carbon of glucose and the carbonyl oxygen, not between the carbonyl carbon and the carbonyl oxygen.

Journal Article↗

PubMed1995

A new phenylpropanoid glucoside and other constituents of Oenanthe javanica.

Three glucosides (1-3), together with known phenylpropanoids and polyacetylenes were isolated from Oenanthe javanica Blume (DC.). Glucoside 1, named oenanthoside A, is a new phenylpropanoid glucoside and was determined to be 2,3-methylenedioxy-5-allylphenyl beta-D-glucopyranoside, mainly by NMR techniques. Glucosides 2 and 3 were identified as eugenyl beta-D-glucopyranoside and pinoresinol beta-D-glucopyranoside, respectively. These were found for the first time in this plant.

Anti-Bacterial Agents↗

PubMed1992

[The antigastroulcerative activity of beta-sitosterol-beta-D-glucoside and its aglycone in rats].

Beta-sitosterol-beta-D-glucoside and its aglycone (the major constituent of the seed oil of Hippophae rhamnoides L.) were investigated for their antigastroulcerative activity in rats. Two experimental gastric ulcer models were selected: chronic acetic acid-induced ulcers and cold stress-induced ulcers. Both the glucoside and its aglycone showed antiulcerative activity in chronic acetic acid-induced gastric ulcer models, and their effects were at least comparable to the effects of wishupin in combination with cimetidine. The effect of aglycone appears better than the glucoside's. Glucoside also showed visibly antiulcerative effects on cold stress-induced ulcers, but wishupin combined with cimetidine did not have such effects.

Acetates↗

PubMed1985

Xanthurenic acid 8-O-beta-D-glucoside, a novel tryptophan metabolite in eye-color mutants of Drosophila melanogaster.

An unknown fluorescent metabolite has been isolated from heads of eye-color mutants of Drosophila melanogaster. Only a few mutations cause it to accumulate, viz. cardinal (cd), dark red brown (drb), Henna-recessive (Hnr), purple (pr), Punch2 (Pu2), Punch-Grape (PuGr), and scarlet (st). After purification by ion-exchange chromatography, the spectroscopic, chemical, and enzymatic analyses revealed that it is a novel quinoline derivative: xanthurenic acid 8-O-beta-D-glucoside. Feeding experiments suggest that this glucoside is synthesized from 3-hydroxykynurenine and that free xanthurenic acid is not a precursor. The results from the analysis for its occurrence in double mutants, together with the fact that xanthurenic acid 8-glucoside share the same precursor as xanthurenic acid and xanthommatin, suggest that xanthurenic acid 8-glucoside formation is closely related to the regulation of the last step in the biosynthesis of xanthommatin.

Animals↗

PubMed2001

Utilizing genetically engineered bacteria to produce plant-specific glucosides.

Plant-derived glucosides have attracted much attention due to their widespread applications. This class of products is difficult to isolate or to synthesize in pure form because of the resulting low yields. Thus, simple approaches for the generation of such glucosides would be highly beneficial. We purified and characterized a novel glucosyltransferase from plant cell suspension cultures of Rauvolfia serpentina, which showed rather low substrate specificity. We obtained its cDNA and expressed the active recombinant protein in bacteria (Escherichia coli) with excellent plant-specific glucosylation efficiencies. Compared with the plant system, the bacteria delivered the new enzyme, which was in the form of a soluble or matrix-bound enzyme, approximately 1800 times more efficiently for the synthesis of a wide range of glucosides. More importantly, the engineered E. coli strain allowed for in vivo glucosylation and release of the product into the culture medium, as shown by the formation of arbutin, which is a potent inhibitor of human melanin biosynthesis with commercial value.

Arbutin↗

PubMed2004

Arabidopsis glycosyltransferases as biocatalysts in fermentation for regioselective synthesis of diverse quercetin glucosides.

Regioselectivity of glycosyltransferases offers an important means to overcome the limitations of chemical synthesis of small molecule glycosides. In this study we explore a large multigene family of UDP-glucose:glycosyltransferases of Arabidopsis for their potential as novel biocatalysts for in vitro synthesis and whole-cell catalysis. We used quercetin as a substrate for this study because the flavonol and its glycosides have important medicinal properties and the metabolite provides a complex structure for regioselective glucosylation. We analyzed the activity of 91 recombinant enzymes for in vitro activity toward quercetin and discovered 29 that are capable of glucosylating the substrate. We demonstrate the first enzymic synthesis of a range of glucosides in vitro, including the 3-O-, 7-O-, 3'-O-, and 4'-O-monoglucosides, 3,7-di-O-glucoside, and 7,3'-di-O-glucoside. We also show that the regioselectivity of glucosylation can be maintained when the enzymes are used as whole-cell biocatalysts in Escherichia coli.

Arabidopsis↗

PubMed1978

Chemical constituents of gentianaceae XXIII: tetraoxygenated and pentaoxygenated xanthones and xanthone O-glucosides of Swertia angustifolia Buch.-Ham.

The whole plant extract of Swertia angustifolia Buch.-Ham., collected at different stages of growth, contained 14 tetraoxygenated and five pentaoxygenated xanthones and xanthone 1-O-glucosides. Of the eight xanthone 1-O-glucosides isolated, five were previously unreported in nature. The xanthones are broadly based on 1,3,5,8- and 1,3,7,8-oxygenated systems, with an added oxygen function at C-4 in some compounds, and represent a number of methoxylated patterns. The content and relative abundance of the free xanthones and their 1-O-glucosides changed with plant growth. These results are the first demonstration of the variation in chemical characters in the different parts of a Swertia species during its ontogeny. The biolgocial significance of these results is appraised.

Glucosides↗

PubMed1975

Study of a corn (Zea mays L.) mutant (blue fluorescent-1) which accumulates anthranilic acid and its beta-glucoside.

A corn (Zea mays L.) mutant, blue fluorescent-1 (bf), is described that shows ultraviolet light induced blue fluorescence in young seedling leaves if homozygous for the mutant gene, and in anthers if either homozygous or heterozygous. The blue fluorescent compounds were extracted with acetone and separated by paper chromatography. Anthranilic acid was present and the beta-glucoside was also identified by paper chromatography and beta-glucosdase and acid treatment. A third major fluorescent compound was not identified, but it was convertible to anthranilic acid by acid treatment. Anthranilate synthetase from mutant plants was 3-40 times more active and was also more resistant to feedback inhibition by tryptophan than was the enzyme from normal plants. The high activity and feedback resistance would both lead to anthranilate accumulation. Anthranilate-phosphoribosylpyrophosphate phosphoribosyltransferase (PR transferase), the enzyme which usually utilizes anthranilate in the tryptophan pathway, was inhibited by the beta-glucoside of anthranilic acid in a noncompetitive manner and showed very little activity in the mutant plant extract. This inhibition of the enzyme which utilizes anthranilate would also lead to accumulation. Apparently the oversynthesis of anthranilate leads to the formation of the beta-glucoside, which inhibits anthranilate utilization. The fluorescent compounds are absent in seed, but form on germination. The levels decrease with age after 35 days postgermination, but are still present in leaves during grain filling.

Anthranilate Phosphoribosyltransferase↗

PubMedDate not supplied

Formation of glucoside conjugate of acetaminophen by fungi separated from soil.

The phase II metabolite of acetaminophen in filamentous fungi and actinomycetes separated from soil was investigated. Fifty-four filamentous fungi and twenty-seven actinomycetes were screened to transform acetaminophen. The metabolites of acetaminophen were assayed using liquid chromatography-tandem mass spectrometry. The only metabolite was subject to enzymatic hydrolysis to confirm its structure. Acetaminophen was converted into glucoside conjugate, by filamentous fungi JX1-60, LN17-2, LN20-1 and the yield of the conjugate was 60.01%, 44.27%, 100%, respectively, and no phase I metabolites were detected. Glucoside conjugation of acetaminophen in filamentous fungi differs from the phase II metabolism of glucuronidation in humans. The fungus LN20-1 could be a suitable model to synthesize glucoside conjugate of acetaminophen.

Acetaminophen↗

PubMed2002

Novel carotenoid glucoside esters from alkaliphilic heliobacteria.

Pigments of three species of alkaliphilic heliobacteria of the genus Heliorestis, H. daurensis, H. baculata and an undescribed species Heliorestis strain HH, were identified using spectroscopic methods. In these species, bacteriochlorophyll g esterified with farnesol was present, as for other heliobacteria. The carotenoids consisted of 4,4'-diaponeurosporene, also found in other heliobacteria, plus the novel pigments OH-diaponeurosporene glucoside esters (C16:0 and C16:1). In addition, trace amounts of biosynthetic intermediates, OH-diaponeurosporene and OH-diaponeurosporene glucoside, were found. Trace amounts of a carotenoid with 20 carbon atoms, 8,8'-diapo-zeta-carotene, were also found in these species as well as in the non-alkaliphilic heliobacteria. The non-alkaliphilic species Heliophilum fasciatum also contained trace amounts of the two OH-diaponeurosporene glucoside esters. The results are used to predict the pathway of carotenoid biosynthesis in heliobacteria.

Bacteria↗

PubMed2005

Amaranthin in feather cockscombs is synthesized via glucuronylation at the cyclo-DOPA glucoside step in the betacyanin biosynthetic pathway.

Uridine 5'-diphosphate (UDP)-glucuronic acid: cyclo-DOPA 5-glucoside glucuronosyltransferase activity was detected in a crude extract prepared from the purple flowers of feather cockscombs. This suggests that the glucuronic acid moiety of amaranthin and its derivatives may be introduced at the cyclo-DOPA glucoside step, but not at the betanidin glucoside step.

Betacyanins↗

PubMed1992

Continuous spectrophotometric assays for beta-glucosidases acting on the plant glucosides L-picein and prunasin.

The neutral pH optimum beta-glucosidases of mammalian liver and almonds are each capable of hydrolyzing a number of plant glucosides, including L-picein (p-hydroxyacetophenone-beta-D-glucoside) and prunasin (D-mandelonitrile-beta-D-glucoside). Taking advantage of the marked differences in the spectra of the substrate/product pairs of L-picein/p-hydroxyacetophenone and prunasin/mandelonitrile, we have devised spectrophotometric assays that permit the continuous monitoring at pH 7.0 of p-hydroxyacetophenone (piceol) release from L-picein by guinea pig hepatic cytosolic beta-glucosidase and mandelonitrile from prunasin by almond beta-glucosidase. When L-picein hydrolysis was monitored at 320 nm and prunasin at 282 nm, the molar absorption coefficients determined for their products, namely piceol and mandelonitrile, were 3200 and 1360 M-1 cm-1, respectively. The kinetic parameter Km and Vmax values obtained using these spectrophotometric procedures for the guinea pig liver cytosolic beta-glucosidase acting on L-picein were 0.88 mM and 5.29 x 10(5) units/mg protein and for the almond beta-glucosidase acting on prunasin, Km 1.1 mM and Vmax 5.24 x 10(6) units/mg protein. These values agreed well with previously reported values obtained using less convenient, discontinuous assay procedures.

Animals↗

PubMed1983

Acylhydrolases from parsley (Petroselinum hortense). Relative distribution and properties of four esterases hydrolyzing malonic acid hemiesters of flavonoid glucosides.

In parsley, malonylated flavonoid glycosides are formed in response to ultraviolet irradiation and accumulate in the vacuoles. Involvement of malonyltransferases, which catalyze the transfer of malonic acid from malonyl-coenzyme A to either flavone/flavonol 7-O-glucosides or flavonol 3-O-glucosides, has been described previously. These enzymes are present in very young leaf buds, and their activities decrease rapidly when leaves begin to unfold, while at the same time esterase activity is developing. The latter enzyme activity continues to increase with tissue age. Four esterases, distinguished by pI's of 3.8, 3.9, 4.0, and 4.05, were purified to apparent homogeneity from parsley leaves and shown to hydrolyze malonic acid hemiesters of flavonoid glucosides. These esterases are unspecific and are best described as one acetyl- and three arylesterases on the basis of inhibition studies by 4-chloromercuribenzoic acid and diisopropyl fluorophosphate. Esterases and malonic acid hemiesters appear to be separated from each other within the parsley leaf cell, and only on disruption of the cells do the respective substrates become available to the enzymes. Involvement of esterases in formation of wound periderm in parsley plants is suggested.

Acyltransferases↗

PubMed1992

The biosynthesis of cyanogenic glucosides in seedlings of cassava (Manihot esculenta Crantz).

A microsomal system catalyzing the in vitro synthesis of the aglycones of the two cyanogenic glucosides linamarin and lotaustralin has been isolated from young etiolated seedlings of cassava (Manihot esculenta Crantz). A prerequisite to obtain active preparations is the complete removal of the endosperm pellicle covering the cotyledons before seedling homogenization. The rates of conversion of the parent amino acids valine and isoleucine to their cyanohydrins are 19 and 6 nmol/h/mg protein, respectively. The conversion rates for the corresponding oximes (2-methylpropanal oxime and 2-methylbutanal oxime) are 475 and 440 nmol/h/mg protein and for the nitriles (2-methylpropionitrile and 2-methylbutyronitrile) 45 and 75 nmol/h/mg protein. With the exception of 2-cyclopentenylglycine, none of the additionally tested amino acids are metabolized, whereas a broad substrate specificity is observed using oximes and nitriles as substrates. The in vitro biosynthesis is photoreversibly inhibited by carbon monoxide, demonstrating the involvement of cytochrome P450 in the hydroxylation processes. All tissues of the cassava seedling contain cyanogenic glucosides. The microsomal enzyme system responsible for their synthesis is restricted to the cotyledons and their petioles. This demonstrates that the cyanogenic glucosides are actively transported to other parts of the seedling. The enzyme activity decreases with the height of the etiolated seedling and is barely detectable in seedlings above 75 mm.

Glucosides↗

PubMed1976

Studies on the transport of aliphatic glucosides by hamster small intestine in vitro.

It has been found (1) that glucosides with a long alkyl chain (2-18 carbon atoms) as the aglycone can be transported by carrier-mediated processes in the hamster small intestine in vitro, (2) that these glucosides interact with the glucose carrier, and (3) that they compete with glucose and analogs for the binding to the carrier. The are Na+- and phlorizin-insensitive components of uptake for the long chain alkyl glucosides which suggest additional interactions or uptake processes.

Animals↗

PubMed1991

Active and monomeric human red cell glucose transporter after high performance molecular-sieve chromatography in the presence of octyl glucoside and phosphatidylserine or phosphatidylcholine.

The human red cell glucose transporter (Glut 1) was purified by ion-exchange chromatography in the presence of octyl glucoside. The state of association of the protein was studied, and the transport activity was determined after exchange of copurified membrane lipids for phosphatidylserine (PS) or phosphatidylcholine (PC). The purpose was to analyze the Glut 1 preparation for homogeneity and activity prior to attempts at crystallization. Analyses by high performance molecular-sieve chromatography showed that the Glut 1 was monomeric immediately after the ion-exchange purification: the Mr of the Glut 1 polypeptide was estimated to be 49,000 +/- 6000 by TSKgel G3000SW chromatography monitored by low-angle laser light-scattering photometry, differential refractometry and UV photometry. This required determination of the absorption coefficient of the Glut 1, which was measured to be 1.13 +/- 0.03 ml mg-1 cm-1 at 280 nm, referring to the polypeptide concentration. The Mr value is consistent with the cDNA-deduced Mr 54,117 of the very similar HepG2 glucose transporter polypeptide. At 2 degrees C, pH 7 and an ionic strength of 0.06 M, the Glut 1 associated gradually during three days to form oligomers. These formed much more rapidly at room temperature or at high ionic strength. Freshly prepared Glut 1 retained high activity after separation from membrane lipids on a TSKgel G3000SW column in the presence of 40 mM octyl glucoside and 1 mM PS or PC. In contrast, most of the activity was lost when the membrane lipids were separated from the protein in the absence of eluent lipids. The presence of a phospholipid was thus essential for retention of high activity of the Glut 1 in octyl glucoside and PC was nearly as effective as PS.

Chromatography, Gel↗

PubMed1987

Evidence for bile acid glucosides as normal constituents in human urine.

A glucosyltransferase catalysing formation of bile acid glucosides was recently isolated from human liver microsomes. In order to investigate the potential occurrence of such bile acid derivatives in vivo, a method was devised for their isolation and purification from urine. Conditions were established with the aid of glucosides of radiolabelled, unconjugated glycine and taurine conjugated bile acids prepared enzymatically using human liver microsomes. Analysis by gas chromatography and mass spectrometry of methyl ester trimethylsilyl ether derivatives indicated the excretion of glucosides of nonamidated hyodeoxycholic, chenodeoxycholic, deoxycholic, ursodeoxycholic and cholic acids and of glycine and taurine conjugated chenodeoxycholic and cholic acids. Additional compounds were present giving mass spectral fragmentation patterns typical of di- and trihydroxy bile acid glycosides. Semiquantitative estimates indicated a total daily excretion of about 1 mumol.

Bile Acids and Salts↗