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PubMed1975

Factors influencing the formation and stability of D-glucoside 3-dehydrogenase activity in cultures of Agrobacterium tumefaciens.

D-glucoside 3-dehydrogenase specific activity in Agrobacterium tumefaciens was maximal towards the end of the exponential growth phase of batch cultures; over 90% of the activity disappeared within the next 15 h. Manganese ions, although essential for growth of the organism, strongly repressed D-glucoside 3-dehydrogenase synthesis in sucrose medium but had little effect when the carbon source was methyl alpha-D-glucoside. D-Glucoside 3-dehydrogenase activity increased linearly with increasing specific growth rate in chemostat cultures limited by carbon, nitrogen, phosphate or manganese when methyl alpha-D-glucoside was the carbon source. High enzyme activity was found with sucrose as carbon source only when the growth medium was manganese-limited. D-Glucoside 3-dehydrogenase activity disappeared from A. tumefaciens incubated in carbon- and nitrogen-free medium or in nitrogen-free medium containing succinate, but on continued incubation the activity returned and was then stable. The recovery of activity could be prevented by chloramphenicol or erythromycin. Bacteria containing the recovered dehydrogenase activity could not convert sucrose to 3-ketosucrose when oxygen acted as the terminal electron acceptor, but produced 3-ketosucrose at the normal rate in the presence of ferricyanide. D-Glucoside 3-dehydrogenase activity disappeared irreversibly from bacteria incubated in nitrogen-free medium containing sucrose. Loss of activity followed first order kinetics in bacteria taken from nitrogen-, phosphate- or manganese-limited chemostat steady states; an accelerating rate of decay occurred in cells grown under carbon-limitation. 8-Hydroxyquinoline, chloramphenicol, erythromycin, 2,4-dinitrophenol and manganese ions could reduce the rate of decay.

Alcohol Oxidoreductases↗

PubMed1970

The biosynthesis of steryl glucosides in plants.

Mitochondrial preparations from pea root (Pisum sativum L. var. Alaska) cauliflower inflorescence (Brassica cauliflora Gars.) and avocado inner mesocarp (Persea americana Mill. var. Fuerte), and chloroplast preparations from spinach leaf (Spinacia oleracea L. var. Bloomsdale) incorporate glucose into steryl glucoside and acylated steryl glucoside when either uridine diphosphate-glucose or uridine diphosphate-galactose is supplied as precursor. In the case of pea root mitochondria, galactosyl diglycerides are not formed from either nucleotide sugar. In the case of spinach chloroplasts only 3% of the metabolized uridine diphosphate-galactose is found as steryl glycosides. Time course experiments indicate that the steryl glucoside is the precursor of the acylated steryl glucoside. The effect of pH on the over-all reaction and analysis of the reaction products suggest that the glucosylation of the sterol has a pH optimum of 8 to 9, and the pH optimum for the acylation of the steryl glucoside is 6.5 to 7. The synthesis of steryl glucoside and acylated steryl glucoside, catalyzed by acetone powders of pea root mitochondria, is stimuated by added sitosterol and stigmasterol.

Galactose↗

PubMed1969

Phospho-beta-glucosidases and beta-glucoside permeases in Streptococcus, Bacillus, and Staphylococcus.

The presence of phospho-beta-glucosidases and beta-glucoside permeases was found in strains of Streptococcus, Bacillus, and Staphylococcus. In streptococci, the phospho-beta-glucosidase activity depends on the antigenic group. The highest activity was found in strains of group D. In group D strains, phospho-beta-glucosidase activity is induced by beta-methyl glucoside and cellobiose but not by thiophenyl beta-glucoside (TPG). With the exception of four strains isolated in Japan, all strains of B. subtilis tested possess an inducible phospho-beta-glucosidase activity, beta-methyl glucoside, cellobiose, and TPG acting as inducers. S. aureus strains possess phospho-beta-glucosidase A but not phospho-beta-glucosidase B, whereas most S. albus strains show no detectable phospho-beta-glucosidase activity. The prompt fermentation of beta-methyl glucoside by S. aureus strains could serve as an additional criterion for their differentiation from S. albus. A comparative investigation of the active uptake of (14)C-TPG showed that a Streptococcus group D strain and a B. subtilis strain posses two inducible permeases with characteristics similar to the beta-glucoside permeases I and II of Enterobacteriaceae. In S. aureus, TPG is accumulated by a constitutive permease with high affinity for aromatic beta-glucosides and glucose. The active uptake of TPG by S. aureus appears to depend on the activity of the phosphoenol pyruvate-dependent phosphotransferase system.

Bacillus↗

PubMed1990

Hydrolysis of pyridoxine-5'-beta-D-glucoside by a broad-specificity beta-glucosidase from mammalian tissues.

Research was conducted to evaluate the ability of a broad-specificity beta-glucosidase in mammalian tissues to catalyze the hydrolytic release of free pyridoxine from pyridoxine-5'-beta-D-glucoside, a naturally occurring form of vitamin B6 in plant-derived foods. Activity was detected in liver and intestinal mucosa using tritiated pyridoxine glucoside as a substrate. In the rat and guinea pig, enzyme activity was greater in intestine than in liver or kidney while even greater activity was detected in human intestinal tissue. Reaction rates were, however, low in all tissues. Hydrolysis of the synthetic substrate 4-methylumbelliferyl-beta-D-glucoside was also greatest in intestinal tissue. The characteristics of the enzymatic hydrolysis of pyridoxine glucoside to pyridoxine included: (i) most activity in the soluble tissue fraction, (ii) a pH optimum of approximately 6.0, and (iii) inhibition caused by the addition of sodium taurocholate. These characteristics are very similar to those of the broad-specificity beta-glucosidase in mammalian tissues with respect to the hydrolysis of a variety of naturally occurring and synthetic substrates. The apparent Km was greater than 2 mM for pyridoxine glucoside hydrolysis by intestinal preparations of each species, which is much greater than expected intestinal concentrations derived from dietary sources. In vivo studies have indicated that the intestine is involved in the metabolic utilization of dietary pyridoxine glucoside. The results observed here suggest that an alternate process, possibly involving intestinal microorganisms, may also be involved in the in vivo hydrolysis of pyridoxine glucoside.

Animals↗

PubMed1994

Characterization of hepta-beta-glucoside elicitor-binding protein(s) in soybean.

We are studying the cellular signalling pathway leading to pterocarpan phytoalexin biosynthesis in soybean that is induced by a branched hepta-beta-glucoside originally isolated from the mycelial walls of the phytopathogenic oomycete, Phytophthora megasperma f. sp. glycinea. Our research has focused on the first step in this signal pathway, namely the specific recognition of the hepta-beta-glucoside elicitor by plasma-membrane-localized binding protein(s) in soybean cells. Binding of a radio-iodinated derivative of the elicitor-active hepta-beta-glucoside by membrane elicitor-binding proteins is specific, reversible, saturable and of high affinity (Kd = 0.75 nM). After solubilization using the non-ionic detergent n-dodecylsucrose, the elicitor-binding proteins retain the binding affinity (Kd = 1.8 nM) for the radiolabelled elicitor and the binding specificity for elicitor-active oligoglucosides. A direct correlation is observed between the ability of elicitor-active and structurally related inactive oligoglucosides to displace labelled elicitor from the elicitor-binding proteins and the elicitor activity of the oligosaccharides. Thus, the elicitor-binding proteins recognize the same structural elements of the hepta-beta-glucoside elicitor that are essential for its phytoalexin-inducing activity, suggesting that the elicitor-binding proteins are physiological receptors for the elicitor. Current research is directed toward the purification and cloning of the hepta-beta-glucoside elicitor-binding proteins. Purification and characterization of the hepta-beta-glucoside-binding protein(s) or their corresponding cDNAs is a first step toward elucidating how the hepta-beta-glucoside elicitor triggers the signal transduction pathway that ultimately leads to the synthesis of phytoalexins in soybean.

Carbohydrate Sequence↗

PubMed1997

Ceramide glucosylation in bean hypocotyl microsomes: evidence that steryl glucoside serves as glucose donor.

The formation of glucosylceramide, the predominant sphingolipid in plant tissues, was examined in microsomes from wax bean hypocotyls. Membranes were incubated with UDP-[14C]glucose in an assay mixture. The lipid extracts obtained from the assays were separated by thin-layer chromatography, and the radioactivity incorporated into glucosylceramide, steryl glucoside, and acylated steryl glucoside was determined. Although the formation of glucosylceramide was detected and characterized, several lines of evidence contradicted the assumption that UDP-glucose is the immediate glucose donor for glucosylceramide formation in plants: PDMP (DL-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol), an inhibitor of ceramide glucosyltransferase in animal tissues, did not inhibit glucosylceramide formation in bean microsomes. Addition of UDP-glucose pyrophosphorylase during the assay to degrade UDP-[14C]glucose blocked the further production of labeled steryl glucoside, but did not prevent the continued formation of labeled glucosylceramide. Omitting UDP-[14C]glucose and including steryl [14C]glucoside in the assay resulted in the formation of labeled glucosylceramide. Collectively, these results suggest that glucosylceramide formation in plants does not utilize UDP-glucose as the immediate glucose donor, as has been demonstrated for the reaction in animal tissues, and that steryl glucoside serves as glucose donor for ceramide formation. This study, the first to examine glucosylceramide formation in plants, provides evidence for a novel enzymatic reaction in sphingolipid synthesis as well as a new, metabolic role for steryl glucoside in plant tissues.

Ceramides↗

PubMed1976

Alkyl glucosides as effective solubilizing agents for bovine rhodopsin. A comparison with several commonly used detergents.

The suitability of octyl and decyl-beta-D-glucoside as solubilizing agents for the bovine retinal rod outer segment disc membrane was investigated and compared to that of hexadecyltrimethylammonium bromide, N,N-dimethyldodecylamine oxide, Emulphogene BC-720 and digitonin. The properties measured included the thermal stability of rhodopsin, regenerability of bleached rhodopsin by addition of 11-cis-retinal, and the rate of denaturation of bleached rhodopsin as measured by changes in the ultraviolet CD spectrum. Denaturing tendencies of the detergents were also evaluated by observing their effects on the absorption and CD spectra of sperm whale metmyoglobin. Our results demonstrate that octyl glucoside is superior to the other detergents, with the possible exception of digitonin, by the above criteria. Unlike digitonin, however, octyl glucoside affords rapid solubilization of the disc membrane and is itself highly soluble. Decyl glucoside has properties equivalent or superior to octyl glucoside, but salts and buffers interfere with its ability to solubilize the disc membrane. The well defined chemical composition, ease of removal by dialysis, and non-denaturing properties of the alkyl glucosides make them attractive detergents for membrane research.

Animals↗

PubMed1996

Acylated pelargonidin 3-sambubioside-5-glucosides in Matthiola incana.

Ten acylated pelargonidin 3-sambubioside-5-glucosides were isolated from the red-purple flowers of Matthiola incana, and also pelargonidin 3-glucoside was isolated from the brownish-red flowers of this plant. FAB mass measurements of 10 acylated anthocyanins gave their molecular ions [M]+ at 903-1195 m/z, which were based on acylated pelargonidin 3-sambubioside-5-glucosides with malonic acid, sinapic acid, p-coumaric acid, caffeic acid and/or ferulic acid. This was confirmed by the analysis of NMR spectra and the experiments of acid and alkaline hydrolysis. By spectral and chemical methods, seven of the 10 pigments were determined to be pelargonidin 3-O-[2-O-(2-O-(acyl-I)-beta-D-xylopyranosyl)- 6-O-(acyl-II)-beta-D-glucopyranoside]-5-O-[6-O-(malonyl)-beta-D- glucopyranoside], in which acyl moieties varied between sinapic, ferulic, caffeic and p-coumaric acids. The occurrence of these pigments was examined in 10 red-purple, 10 salmon-pink, three apricot and three copper colour cultivars of M. incana by HPLC. The acylated pelargonidin 3-sambubioside-5-glucosides were present as the dominant pigments in the red-purple, salmon-pink and apricot colour cultivars. On the other hand, pelargonidin 3-glucoside was present as a dominant anthocyanin in the copper colour cultivars and also pelargonidin 3-sambubioside-5-glucoside was confirmed by HPLC as a minor pigment in the copper colour flowers.

Acylation↗

PubMed1983

Studies on the metabolism and excretion of 1-naphthol, 1-naphthyl-beta-D-glucuronide, and 1-naphthyl-beta-D-glucoside in the mouse.

Radiolabeled 1-naphthyl-beta-D-glucuronide and 1-naphthyl-beta-D-glucoside were synthesized from 1-[14C]naphthol. The fate of the three compounds in male mice was studied. After a po dose of 45 mg/kg of 1-naphthol, 100 mg/kg of 1-naphthyl glucuronide, and 100 mg/kg of 1-naphthyl glucoside, 95, 93, and 81%, respectively, of the administered dose were eliminated 72 hr after treatment. 1-Naphthyl glucoside was eliminated more slowly than the other two compounds. 1-Naphthol was metabolized predominantly to the sulfate and the glucuronide conjugates, whereas a portion of 1-naphthyl glucoside was eliminated directly or cleaved and then reconjugated to form the sulfate and the glucuronide conjugates. 1-Naphthyl glucuronide was excreted as parent compound and sulfate, indicating hydrolysis and resynthesis. When the glucoside was administered at three doses (10, 50, and 100 mg/kg), it was observed that the lower doses of the glucoside were more readily eliminated in the urine than the higher doses. Larger amounts of the parent compound were found in the excreta at the lower doses than at the higher doses.

Animals↗

PubMed2004

Skin absorption and metabolism of a new vitamin E prodrug, delta-tocopherol-glucoside: in vitro evaluation in human skin models.

The aim of this study was to investigate the cutaneous penetration and metabolism of the new vitamin E prodrug delta-tocopherol glucoside (delta-TG), as compared to those of common vitamin E acetate, in vitro, both in reconstituted human epidermis and in viable human skin. Better diffusion was observed with alpha-tocopherol acetate (alpha-TAc) than with delta-tocopherol glucoside in both skin models, at 0.1% and 0.05% in a myritol solution; however, no metabolism was detected with alpha-tocopherol acetate. In all conditions tested (two skin models, two concentrations, three test times, and compartmental analysis) the delta-tocopherol glucoside was metabolized into free tocopherol. In the reconstituted human epidermis, after 18 h, over 90% of the delta-tocopherol glucoside was bioconverted. In the viable human skin, the extent of metabolism was about 20%, with 0.12 and 0.10 microg/cm2 of delta-tocopherol glucoside in the stratum corneum and epidermis, respectively. After topical application, the delta-tocopherol glucoside had a considerable reservoir effect, associated with gradual delivery of free tocopherol. The use of this gluco-conjugated vitamin E at a low concentration shows the capability of the skin to metabolize the prodrug in a slow and prolonged manner, making this gluco-conjugated vitamin E an excellent candidate for continuous reinforcement of antioxidants in the skin.

Antioxidants↗

PubMed2006

Arabidopsis thaliana beta-Glucosidases BGLU45 and BGLU46 hydrolyse monolignol glucosides.

In higher plants, beta-glucosidases belonging to glycoside hydrolase (GH) Family 1 have been implicated in several fundamental processes including lignification. Phylogenetic analysis of Arabidopsis thaliana GH Family 1 has revealed that At1g61810 (BGLU45), At1g61820 (BGLU46), and At4g21760 (BGLU47) cluster with Pinus contorta coniferin beta-glucosidase, leading to the hypothesis that their respective gene products may be involved in lignification by hydrolysing monolignol glucosides. To test this hypothesis, we cloned cDNAs encoding BGLU45 and BGLU46 and expressed them in Pichia pastoris. The recombinant enzymes were purified to apparent homogeneity by ammonium sulfate fractionation and hydrophobic interaction chromatography. Among natural substrates tested, BGLU45 exhibited narrow specificity toward the monolignol glucosides syringin (K(m), 5.1mM), coniferin (K(m), 7mM), and p-coumaryl glucoside, with relative hydrolytic rates of 100%, 87%, and 7%, respectively. BGLU46 exhibited broader substrate specificity, cleaving salicin (100%), p-coumaryl glucoside (71%; K(m), 2.2mM), phenyl-beta-d-glucoside (62%), coniferin (8%), syringin (6%), and arbutin (6%). Both enzymes also hydrolysed p- and o-nitrophenyl-beta-d-glucosides. Using RT-PCR, we showed that BGLU45 and BGLU46 are expressed strongly in organs that are major sites of lignin deposition. In inflorescence stems, both genes display increasing levels of expression from apex to base, matching the known increase in lignification. BGLU45, but not BGLU46, is expressed in siliques, whereas only BGLU46 is expressed in roots. Taken together with recently described monolignol glucosyltransferases [Lim et al., J. Biol. Chem. (2001) 276, 4344-4349], our enzymological and molecular data support the possibility of a monolignol glucoside/beta-glucosidase system in Arabidopsis lignification.

Arabidopsis↗

PubMed2000

Screening for limonoid glucosides in Citrus tangerina (Tanaka) Tseng by high-performance liquid chromatography-electrospray ionization mass spectrometry.

A screening method for limonoid glucosides in the peel of Citrus tangerina (Tanaka) Tseng, which utilizes high-performance liquid chromatography (HPLC) with diode-array detection and interfaced to electrospray ionization mass spectrometry, has been developed. In this way, the UV-Vis spectra and the mass spectra indicate the presence of limonoid glucosides without the necessity of isolating the individual compounds. Two major limonoid glucosides--obacunone glucoside (OG) and nomilin glucoside (NG)--were identified in the methanol extract of the peel. The two limonoid glucosides were taken as the target and isolated by means of preparative HPLC on a C18 reversed-phase column with an acidic acetonitrile-water mobile phase. The structures of OG and NG were further confirmed by nuclear magnetic resonance spectrometry.

Chromatography, High Pressure Liquid↗

PubMed1998

The different functions of BglF, the E. coli beta-glucoside permease and sensor of the bgl system, have different structural requirements.

The Escherichia coli BglF protein (EIIbgl) is an Enzyme II (EII) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) which catalyses transport and phosphorylation of beta-glucosides. In addition to its transport function, BglF serves as a beta-glucoside sensor which reversibly phosphorylates BglG, the transcription regulator of the bgl operon. Like many other PTS sugar permeases, the BglF protein is composed of three discrete functional and structural domains: IIAbgl and IIBbgl, which are hydrophilic, and IICbgl, which is hydrophobic. The domains of BglF are covalently linked to one another in the order BCA. The IIAbgl domain contains the first phosphorylation site, which accepts a phosphoryl group from the general PTS protein HPr and delivers it to the second phosphorylation site, located in the IIBbgl domain. This second site can deliver the phosphoryl group either to a beta-glucoside or to BglG. To elucidate the mechanism by which such different substrates can be phosphorylated by the same active site, we decided to try to separate the different phosphorylation activities catalyzed by BglF. To this end we rearranged the BglF domains and constructed IICBAbgl (scrambled-BglF). Scrambled-BglF behaved like wild-type BglF in its ability to be phosphorylated and to phosphorylate BglG in vitro and in vivo. However, it could not catalyze phosphorylation of beta-glucosides in vitro nor their phosphotransfer in vivo, and it could not catalyze BglG dephosphorylation in vitro or in vivo. Therefore, the two reactions induced by beta-glucosides, sugar phosphorylation and BglG dephosphorylation, seem to require a specific domain organization: IIBbgl should precede IICbgl. The order of the B and C domains is irrelevant for BglG phosphorylation, which occurs in the absence of beta-glucosides. Because the domain order affects the way that the domains are able to interact, our results suggest that catalysis of the sugar-induced functions depends on specific interactions between IIBbgl and IICbgl. In light of the previous assumption that domain order in EIIs is immaterial for their function, the finding that the order of the domains is important for the function of BglF as a sugar phosphotransferase raises two possibilities: (a) BglF differs from other EIIs in this regard; (b) BglF represents a subgroup of EIIs in which the requirement for a specific domain order correlates with the ability to transport a set of structurally related sugars.

Amino Acid Sequence↗

PubMed2006

UV-visible spectroscopic investigation of the 8,8-methylmethine catechin-malvidin 3-glucoside pigments in aqueous solution: structural transformations and molecular complexation with chlorogenic acid.

The physicochemical properties of 8,8-methylmethine catechin-malvidin 3-O-glucoside isomers, commonly referred to as catechin-ethyl-malvidin 3-O-glucoside, have been studied in aqueous solutions and compared with those of the parent anthocyanin (malvidin 3-O-glucoside). The hydration and acidity constants (pKh and pKa) of the catechin-ethyl-malvidin 3-O-glucoside pigments and malvidin 3-O-glucoside were determined by UV-visible spectroscopic measurements. The ethyl-linked catechin-malvidin 3-O-glucoside pigments present higher stability toward hydration than the parent anthocyanin. The high resistance of these ethyl-linked pigments toward the hydration is related to the self-association that offers optimal protection from the nucleophilic attack of water. Moreover, the ethyl link may confer to the molecule enough flexibility to undergo intramolecular interaction, further protecting it from hydration and bisulfite discoloration. In the wine pH range (3.2-4.0), due to the low pKa and high pKh values, the ethyl-linked pigments are present as colored forms (flavylium cation and quinonoid bases).

Anthocyanins↗

PubMed2000

Naphthoquinone glucosides of Drosera gigantea from in vitro cultures.

From the shoots of Drosera gigantea propagated under in vitro culture, the rare naphthoquinone glucosides droserone (3,5-dihydroxy-2-methyl-1,4-naphthoquinone) and hydroxydroserone (3,5,8-trihydroxy-2-methyl-1,4-napthoquinone) 5-O-beta-glucosides, together with the free naphthoquinones droserone, hydroxydroserone and plumbagin were isolated. The structures of the glucosides and hydroxydroserone were studied by 2D NMR techniques. The glucosides appear to be responsible for the brown-red (maroon) colour of this plant. Of the other naphthoquinones typical for the family Droseraceae only hydroplumbagin glucoside could be detected, whereas the presence of 7-methyljuglone and rossoliside (= 7-methylhydrojuglone glucoside) was excluded.

Culture Techniques↗

PubMed2004

Quercetin glucosides inhibit glucose uptake into brush-border-membrane vesicles of porcine jejunum.

Recent experimental data point to an interaction of dietary flavonol monoglucosides with the intestinal Na-dependent glucose transporter 1 (SGLT1). To investigate this interaction in more detail, we performed experiments with SGLT1-containing brush-border-membrane vesicles (BBMV) from pig jejunum. The flavonol quercetin-3-O-glucoside (Q3G) concentration-dependently inhibited Na-dependent uptake of radioactively labelled d-glucose into BBMV. Uptake of l-leucine was not inhibited by Q3G, indicating a specific interaction of the glucoside with SGLT1. Whereas the maximal transport rate of concentration-dependent initial glucose uptake was not altered in the presence of Q3G, the constant for half-maximal glucose uptake was increased, suggesting a competitive type of inhibition of glucose uptake by Q3G. Trans-stimulation experiments suggested the transport of Q3G via SGLT1. In addition, Q3G decreased the Na-independent diffusive uptake of glucose into BBMV. Other flavonoids were also tested for their inhibitory effect on d-glucose uptake. Among the tested quercetin glycosides, only the 4'-O-glucoside (Q4G) also inhibited Na-dependent glucose uptake into BBMV, whereas the 3-O-galactoside, the 3-O-glucorhamnoside and the aglycone quercetin itself were ineffective. Glucosides of some other flavonoid classes such as naringenin-7-O-glucoside, genistein-7-O-glucoside and cyanidin-3,5-O-diglucoside were ineffective as well. Thus, dietary quercetin monoglucosides, for example, Q3G and Q4G, have an impact on intestinal nutrient transporters such as SGLT1 and related systems.

Animals↗

PubMed1997

Pharmacokinetics of 2-naphthol following intrapericardial administration, and formation of 2-naphthyl-beta-D-glucoside and 2-naphthyl sulphate in the American lobster, Homarus americanus.

1. Following a 0.25-mg/kg intrapericardial dose of the phenolic compound, 2-naphthol, to the American lobster, Homarus americanus, a two-compartment model best described the disposition of parent [14C]-2-naphthol in the haemolymph. Male and female lobsters had similar alpha-phase half lives of 26 +/- 19 min (mean +/- SD, n = 4) and 29 +/- 15 min respectively. The beta-phase half lives were significantly longer in males, 63.9 +/- 30.9 h, than in females, 30.6 +/- 6.8 h (p < 0.05). The total body clearance for females was 26.4 +/- 6.5 ml x h-1 x kg-1 and was higher than that of males, 11.1 +/- 5.9 ml x h-1 x kg-1 (p < 0.05). 2. 2-Naphthol was converted to 2-naphthyl-beta-D-glucoside (major metabolite) and 2-naphthyl sulphate (minor metabolite) such that at 24 h 39-60.6% of the radioactivity in haemolymph was 2-naphthyl-beta-D-glucoside, 38.6-58.9% 2-naphthol and 0.5-4% 2-naphthyl sulphate. 3. The 2-naphthol-derived radioactivity was > 99% bound to haemolymph proteins at 1 min and > 90% bound at 1 day after the dose, indicating that both 2-naphthol and 2-naphthyl-beta-D-glucoside were highly protein bound. 4. 2-Naphthyl-beta-D-glucoside was slowly eliminated from haemolymph in both males and females, with elimination half lives of 34-78 h. 2-Naphthyl-beta-D-glucoside was the major metabolite in urine samples collected at 5 days after the dose. Hepatopancreas and antennal gland contained glucosidase activities, and the long half life of 2-naphthyl-beta-D-glucoside could be explained by conjugation deconjugation cycling. 5. 2-Naphthyl sulphate was eliminated from haemolymph with a half-life < 10 h and was excreted in urine.

Animals↗

PubMed1994

Sialylation of n-alkyllactosides, galactosides and glucosides by sialyltransferases from rat liver Golgi vesicles.

n-Alkyl alpha- and beta-lactosides, galactosides and glucosides with different alkyl chain lengths (C2, C8, C14 and C20) were synthesized and used as acceptors for sialyltransferases from rat liver Golgi vesicles. The beta-galactosides, beta-glucosides, and both alpha- and beta-lactosides, were sialylated. Keeping the acceptor concentration constant, sialylation rates reached a maximum for the n-octyl alpha- and beta-lactosides, n-octyl beta-galactoside and n-octyl beta-glucoside, respectively. n-Octyl alpha-galactoside and n-octyl alpha-glucoside were not sialylated. The reaction products were characterized by TLC. With n-octyl lactoside and galactoside as acceptors, two major sialylation products were formed. They could be separated by preparative TLC, and their structures were identified as 2-3 and 2-6 sialylated acceptors, respectively, by a combination of periodate oxidation, NaBD4 reduction, permethylation and subsequent analysis by fast atom bombardment mass spectrometry (FAB-MS). The structure of the single product obtained from n-octyl beta-glucoside was determined to be the 2-6 sialylated glucoside. Competition experiments with n-octyl lactoside and lactosylceramide and ganglioside Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-1Cer (GM1) as acceptors for sialyltransferases suggested that SAT-I [NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1Cer (GM3) synthase] was at least in part responsible for the 2-3 sialylation of n-octyl lactoside.

Animals↗