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Glucosidase
Terms modified by Glucosidase Selected AbstractsHYDROLYSIS OF ISOFLAVONE GLYCOSIDES IN SOY MILK BY ,-GALACTOSIDASE AND ,-GLUCOSIDASEJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2009THUY T. PHAM ABSTRACT The objective of this study was to assess the potential of pure ,-galactosidase and ,-glucosidase for hydrolyzing isoflavone glycosides to aglycones in soy milk. Both pure ,-galactosidase and ,-glucosidase were added at various concentrations (0.5, 1.0, 2.0 and 4.0 U/mL) to soy milk made from 4% soy protein isolate and incubated at 37C for up to 240 min. Isoflavones were quantified using high-performance liquid chromatography. The isoflavone contents of soy milk before and after autoclaving were also compared. ,-Glucosidase and ,-galactosidase were both able to hydrolyze the ,-glucosidic linkages in isoflavone glycosides. A range of 43.3 to 77.2% of the total isoflavone glycosides was hydrolyzed at various ,-galactosidase concentrations. The ,-glucosidase hydrolyzed isoflavone glycosides more efficiently than ,-galactosidase. At the most diluted ,-glucosidase concentration (0.5 U/mL), 86.6% of isoflavone glycosides were hydrolyzed to aglycones at 240 min. PRACTICAL APPLICATIONS Isoflavone glycosides, which are mainly found in the bean family, are the inactive forms of isoflavones. However, aglycones, which are the nonsugar component of a glycoside molecule that results from hydrolysis of the isoflavone glycosides, are the biologically active forms. Because of their similarity to female hormone, they are considered a "natural way" to relieve the menopausal symptoms as they prevent certain cancers and improve bone health. Only a small amount of the total isoflavones, however, exists in the aglycone forms in nature. A novel method to produce aglycones from natural isoflavones is highly important. ,-Glucosidase has been claimed to be the only enzyme which is able to hydrolyze isoflavone glycosides to aglycones. However, other enzymes could hydrolyze isoflavone glycosides more efficiently and could be easier to produce. This paper investigates the ability of ,-galactosidase to biotransform isoflavone glycosides to aglycones, as the source of the enzyme is abundant. [source] INHIBITORY POTENTIAL OF WINE AND TEA AGAINST ,-AMYLASE AND ,-GLUCOSIDASE FOR MANAGEMENT OF HYPERGLYCEMIA LINKED TO TYPE 2 DIABETESJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2008YOUNG-IN KWON ABSTRACT Natural ,-amylase and ,-glucosidase inhibitors from food-grade plants offer an attractive strategy to manage postprandial hyperglycemia for type 2 diabetes management via control of starch breakdown and intestinal glucose absorption. In this study, four random sources of red and white wines as well as four types of teas were investigated for ,-amylase and ,-glucosidase inhibitory potential. Water extracts of black tea had the highest ,-glucosidase inhibitory activity, followed by white tea and oolong tea. All the randomly selected red wines had significant ,-glucosidase inhibitory activity compared to white wine. The ,-glucosidase inhibitory activity of the tea and wines correlated to the phenolic content, antioxidant activity and phenolic profile of the extracts. Further, these extracts had less or no ,-amylase inhibitory activity, indicating potential to overcome the side effects of undigested starch. This research has relevance for managing hyperglycemia and related oxidation-linked dysfunction and concurrently reducing problems of undigested starch. PRACTICAL APPLICATIONS In this study anti-diabetic-relevant potential of wines and teas were confirmed in four types of red and white wines as well as four types of commonly available teas using in vitro enzyme assays for alpha-glucosidase and alpha-amylase inhibitory activities. In vitro inhibitory activities of these enzymes provide a strong biochemical rationale for further in vivo studies and dietary management strategy for type 2 diabetes through the control of glucose absorption. Further this phenolic antioxidant-enriched dietary strategy using specific beverage combinations can generate a whole food profile that has the potential to reduce hyperglycemia-induced pathogenesis and also associated complications linked to cellular oxidation stress. [source] HYDROLYSIS OF ISOFLAVONE GLYCOSIDES IN SOY MILK BY ,-GALACTOSIDASE AND ,-GLUCOSIDASEJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2009THUY T. PHAM ABSTRACT The objective of this study was to assess the potential of pure ,-galactosidase and ,-glucosidase for hydrolyzing isoflavone glycosides to aglycones in soy milk. Both pure ,-galactosidase and ,-glucosidase were added at various concentrations (0.5, 1.0, 2.0 and 4.0 U/mL) to soy milk made from 4% soy protein isolate and incubated at 37C for up to 240 min. Isoflavones were quantified using high-performance liquid chromatography. The isoflavone contents of soy milk before and after autoclaving were also compared. ,-Glucosidase and ,-galactosidase were both able to hydrolyze the ,-glucosidic linkages in isoflavone glycosides. A range of 43.3 to 77.2% of the total isoflavone glycosides was hydrolyzed at various ,-galactosidase concentrations. The ,-glucosidase hydrolyzed isoflavone glycosides more efficiently than ,-galactosidase. At the most diluted ,-glucosidase concentration (0.5 U/mL), 86.6% of isoflavone glycosides were hydrolyzed to aglycones at 240 min. PRACTICAL APPLICATIONS Isoflavone glycosides, which are mainly found in the bean family, are the inactive forms of isoflavones. However, aglycones, which are the nonsugar component of a glycoside molecule that results from hydrolysis of the isoflavone glycosides, are the biologically active forms. Because of their similarity to female hormone, they are considered a "natural way" to relieve the menopausal symptoms as they prevent certain cancers and improve bone health. Only a small amount of the total isoflavones, however, exists in the aglycone forms in nature. A novel method to produce aglycones from natural isoflavones is highly important. ,-Glucosidase has been claimed to be the only enzyme which is able to hydrolyze isoflavone glycosides to aglycones. However, other enzymes could hydrolyze isoflavone glycosides more efficiently and could be easier to produce. This paper investigates the ability of ,-galactosidase to biotransform isoflavone glycosides to aglycones, as the source of the enzyme is abundant. [source] In Vitro,Potential of,Ascophyllum nodosum,Phenolic Antioxidant-Mediated ,-Glucosidase and ,-Amylase InhibitionJOURNAL OF FOOD SCIENCE, Issue 3 2010E. Apostolidis ABSTRACT:,Ascophyllum nodosum,is a brown seaweed that grows abundantly in the Northeast coastal region. In this study, the potential of,A. nodosum,for type 2 diabetes management through antioxidant-mediated ,-glucosidase and ,-amylase inhibition was investigated. After the initial screening of 4 locally harvested seaweeds,,A. nodosum,was chosen for its highest phenolic content and was subjected to water extraction. Among extraction ratios of 50 g to 100 to 1000 mL at room temperature, 50 g/400 mL yielded the highest phenolic content of 4.5 mg/g wet weight. For evaluation of extraction temperature ranging from 20 to 80 °C, 50 g/400 mL was chosen as a minimum amount of extractant. Among temperatures studied, extraction at 80 °C resulted in the highest total phenolic contents (4.2 mg/g wet weight). All extracts had similar levels of antioxidant activity in the range of 60% to 70% in terms of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. The 80 °C extract had the highest ,-glucosidase and ,-amylase inhibitory activity with IC50 of 0.24 and 1.34 ,g phenolics, respectively, compared to the IC50 of acarbose, reference inhibitor, being 0.37 and 0.68 ,g. The results show that fresh,A. nodosum,has strong ,-glucosidase and mild ,-amylase inhibitory activities that correlated with phenolic contents. This study suggests a nutraceutical potential of,A. nodosum,based on phytochemical antioxidant and antihyperglycemia activities. [source] Production of ,-Glucosidase and Hydrolysis of Isoflavone Phytoestrogens by Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus casei in SoymilkJOURNAL OF FOOD SCIENCE, Issue 1 2008O.N. Donkor ABSTRACT:, The study determined ,-glucosidase activity of commercial probiotic organisms for hydrolysis of isoflavone to aglycones in fermenting soymilk. Soymilk made with soy protein isolate (SPI) was fermented with Lactobacillus acidophilus LAFTI® L10, Bifidobacterium lactis LAFTI® B94, and Lactobacillus casei LAFTI® L26 at 37 °C for 48 h and the fermented soymilk was stored for 28 d at 4 °C. ,-Glucosidase activity of organisms was determined using ,-nitrophenyl ,-D-glucopyranoside as a substrate and the hydrolysis of isoflavone glycosides to aglycones by these organisms was carried out. The highest level of growth occurred at 12 h for L. casei L26, 24 h for B. lactis B94, and 36 h for L. acidophilus L10 during fermentation in soymilk. Survival after storage at 4 °C for 28 d was 20%, 15%, and 11% greater (P < 0.05) than initial cell counts, respectively. All the bacteria produced ,-glucosidase, which hydrolyzed isoflavone ,-glycosides to isoflavone aglycones. The decrease in the concentration of ,-glycosides and the increase in the concentration of aglycones were significant (P < 0.05) in the fermented soymilk. Increased isoflavone aglycone content in fermented soymilk is likely to improve the biological functionality of soymilk. [source] Glycosidases in soils as affected by cropping systemsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2005Daniel E. Dodor Abstract Glycosidases are a group of soil enzymes that play a major role in degradation of carbohydrates. This study was conducted to assess the impact of crop rotation and N fertilization on the activities of ,- and ,-glucosidases and ,- and ,-galactosidases in plots of two long-term field experiments at the Clarion-Webster Research Center (CWRC) and Northeast Research Center (NERC) in Iowa. Surface-soil (0,15 cm) samples were taken in 1996 and 1997 in corn (Zeamays L.), soybean (Glycinemax (L.) Merr.), oats (Avenasativa L.), or meadow (alfalfa) (Medicago sativa L.) plots that received 0 or 180,kg N ha,1, applied as urea before corn, and an annual application of 20,kg P ha,1 and 56,kg K ha,1. Activities of the four glycosidases were significantly affected by crop rotations in both years at the two sites but not by nitrogen application. In general, higher activities were observed in plots under meadow or oat and the lowest in continuous corn (CWRC) and soybean (NERC). Four-year rotation showed the highest activity, followed by 2-year rotation and monocropping systems. Linear-regression analyses indicated that, in general, the activities of the glycosidases were significantly correlated with microbial-biomass C (r > 0.302, p , 0.05) and microbial-biomass N (r > 0.321, p , 0.05), organic-C (r > 0.332, p , 0.05) and organic-N (r > 0.399, p , 0.01) contents of the soils. Results of this work suggest that multicropping stimulated the activities of the glycosidases. The specific activities of the glycosidases in soils of the two sites studied, expressed as g p -nitrophenol released per,kg of organic C, differed among the four enzymes. The lowest values were obtained for ,-galactosidase and ,-glucosidase, followed by ,-galactosidase and ,-glucosidase. Glycosidasen in Böden unter dem Einfluss von Bewirtschaftungssystemen Glycosidasen stellen eine Gruppe von Bodenenzymen dar, welche eine entscheidende Rolle im Abbau von Kohlenhydraten spielen. Ziel dieser Untersuchungen war die Erfassung des Einflusses von Fruchtfolge und N-Düngung auf die Aktivitäten von ,- und ,-Glucosidasen und ,- und ,-Galactosidasen in zwei Langzeitfeldversuchen, dem Clarion-Webster-Versuchsfeld (CWRC) und dem Northeast-Versuchsfeld (NERC) in Iowa. In den Jahren 1996 und 1997 wurden Oberbodenproben (0,15 cm) von Parzellen unter Mais (Zeamays L.), Sojabohne (Glycine max (L.) Merr.), Hafer (Avena sativa L.) oder Luzerne (Medicago sativa L.) entnommen, welche vor Mais 0 oder 180,kg N ha,1 in Form von Harnstoff sowie jährliche Düngergaben in Höhe von 20,kg P ha,1 und 56,kg K ha,1 erhielten. Über zwei Jahre wurden die Aktivitäten der vier Glycosidasen in beiden Feldversuchen signifikant von der Bewirtschaftung beeinflusst, jedoch nicht von der N-Düngung. Im allgemeinen wurden höhere Enzymaktivitäten in Parzellen unter Luzerne oder Hafer festgestellt und die geringsten unter Maismonokultur (CWRC) bzw. Sojabohne (NERC). Vierjährige Fruchtfolgen zeigten die höchsten Aktivitäten, gefolgt von zweijährigen Fruchtfolgen und Monokulturen. Analysen mittels linearer Regression weisen auf eine Korrelation zwischen Glycosidaseaktivitäten und C (r > 0.332, p , 0.05) und N der mikrobiellen Biomasse (r > 0.321, p , 0.05) sowie den Gehalten an org. C (r > 0.332, p , 0.05) und N (r > 0.399, p , 0.01) hin. Die Ergebnisse dieser Untersuchungen deuten darauf hin, dass die Aktivitäten von Glycosidasen durch mehrjährige Fruchtfolgen stimuliert wurden. Die spezifischen Glycosidaseaktivitäten in den Böden der zwei Feldversuche, berechnet als freigesetztes p -Nitrophenol (g (kg org. C),1), variierten zwischen den vier Enzymen. Die geringsten Werte wurden für ,-Galactosidase und ,-Glucosidase festgestellt, gefolgt von ,-Galactosidase und ,-Glucosidase. [source] Establishment of Retama sphaerocarpa L. seedlings on a degraded semiarid soil as influenced by mycorrhizal inoculation and sewage-sludge amendmentJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2004María del Mar Alguacil Abstract A field experiment was carried out to evaluate the effectiveness of mycorrhizal inoculation with three arbuscular mycorrhizal (AM) fungi (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge), and Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) and the addition of composted sewage sludge (SS) with respect to the establishment of Retama sphaerocarpa L. seedlings, in a semiarid Mediterranean area. Associated changes in soil chemical (nutrient content and labile carbon fractions), biochemical (enzyme activities), and physical (aggregate stability) parameters were observed. Six months after planting, both the addition of composted SS and the mycorrhizal-inoculation treatments had increased total N content, available-P content, and aggregate stability of the soil. Values of water-soluble C and water-soluble carbohydrates were increased only in the mycorrhizal-inoculation treatments. Rhizosphere soil from the mycorrhizal-inoculation treatments had significantly higher enzyme activities (dehydrogenase, protease-BAA, acid phosphatase, and ,-glucosidase) than the control soil. In the short-term, mycorrhizal inoculation with AM fungi was the most effective treatment for enhancement of shoot biomass, particularly with G. mosseae (about 146% higher with respect to control plants). The addition of the composted SS alone was sufficient to restore soil structural stability but was not effective with respect to improving the performance of R. sphaerocarpa plants. Besiedlung eines degradierten semiariden Bodens mit Retama sphaerocarpa L.-Setzlingen, beeinflusst durch Mykorrhiza-Inokulation und Klärschlammzugabe Ein Feldversuch wurde durchgeführt, um den Effekt einer Inokulation mit drei arbuskulären Mykorrhizapilzen (AM) (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) und Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) einerseits und der Zugabe von kompostiertem Klärschlamm (SS) andererseits auf die Besiedlung von Retama sphaerocarpa L.-Setzlingen in einem mediterranen semiariden Gebiet zu untersuchen. Es wurden chemischer Nährstoffgehalt, labile C-Fraktion, biochemische Enzymaktivitäten und physikalische Bodenparameter (Aggregatstabilität) untersucht. Sechs Monate nach der Pflanzung erbrachten beide Behandlungen , die Zugabe von kompostiertem Klärschlamm und die Mykorrhiza-Inokulation , Steigerungen des Gesamtstickstoff-Gehaltes, des verfügbaren Phosphor-Gehaltes sowie der Aggregatstabilität des Bodens. Wasserlöslicher Kohlenstoff und wasserlösliche Kohlenhydrate waren nur nach Mykorrhiza-Inokulation erhöht. Boden aus der Rhizosphäre, der mit Mykorrhizapilzen inokuliert wurde, zeigte signifikant höhere Enzymaktivitäten (Dehydrogenase, Protease-BAA, saure Phosphatase und ,-Glucosidase) als der Kontrollboden. In der kurzen Periode war die Inokulation mit AM-Pilzen die effektivste Behandlung bei der Bildung von Sprossbiomasse, speziell bei G. mosseae (eine um über 146,% höhere Biomasse im Vergleich zu den Kontrollpflanzen). Die Zugabe von kompostiertem Klärschlamm allein war ausreichend, die Stabilität der Bodenstruktur wiederherzustellen, aber sie war nicht effektiv hinsichtlich der Entwicklung der R. sphaerocarpa -Pflanzen. [source] ,-Glucosidase and peroxidase stability in crude enzyme extracts from green beans of Vanilla planifolia AndrewsPHYTOCHEMICAL ANALYSIS, Issue 3 2001Mark J. W. Dignum Abstract The extraction method for ,-glucosidase from green vanilla beans has been studied. The effect of storage of green beans and protein extracts on ,-glucosidase and peroxidase activity was investigated: the best method, resulting in the highest enzyme activities, particularly for glucosidase, was through extraction of very fresh green beans in the presence of BisTris propane buffer at pH 8. The best method for storage of the extracts was at ,80°C after addition of 15% glycerol, when over 90% of initial activity was still present. Peroxidase activity did not change in frozen beans or in frozen extracts. Copyright © 2001 John Wiley & Sons, Ltd. [source] Shear Deactivation of Cellulase, Exoglucanase, Endoglucanase, and ,-Glucosidase in a Mechanically Agitated ReactorBIOTECHNOLOGY PROGRESS, Issue 6 2001Tejas P. Gunjikar Shear deactivation of cellulase and its major component enzymes, viz., exoglucanase (exo -1,4-,- D -glucan-4-cellobiohydrolase), endoglucanase (endo -1,4-,- D -glucanhydrolase), and 1,4-,-glucosidase, was carried out by exposing cellulase to shear in a mechanically agitated reactor in the presence as well as in the absence of the substrate cellulose. Cellulase was found to undergo deactivation when subjected to shear, and the extent of deactivation increased with increasing speed of agitation. Among the three major component enzymes of cellulase, exoglucanase showed rapid deactivation and contributed the most to cellulase deactivation. The presence of a substrate did not affect the deactivation of cellulase. [source] Dissection of Conformationally Restricted Inhibitors Binding to a ,-GlucosidaseCHEMBIOCHEM, Issue 5 2006Tracey M. Gloster Dr. Glycosidase inhibition, important in the quest for highly potent and specific drugs, can be achieved by mimicking the oxocarbenium ion-like transition-state species that form during the catalytic mechanism. Castanospermine (left) and calystegine B2 (right) are potent inhibitors that are conformationally restricted by the inclusion of ethylene linkers. Their binding to a ,-glucosidase from Thermotoga maritima has been studied by structural, kinetic and thermodynamic methods. Although both compounds inhibit with a similar potency, castanospermine derives the majority of it energetic contribution from enthalpy whereas calystegine B2 binding is more entropically driven. [source] Biaryls and Heterobiaryls as ,-Glucosidase and Protein Tyrosine Phosphatase Inhibitors.CHEMINFORM, Issue 28 2005Ashoke Sharon Abstract For Abstract see ChemInform Abstract in Full Text. [source] Electrophoretically mediated reaction of glycosidases at a nanoliter scaleELECTROPHORESIS, Issue 6 2003Yoshimi Kanie Abstract We have investigated electrophoretically mediated microanalysis (EMMA) for the assay of a native glyco-enzyme. As a representative of this class of enzyme, ,-glucosidase was selected, and the reaction was analyzed. Our EMMA was based on the plug-plug interaction of enzyme and substrate plugs, which is essential to reduce quantities of materials. Furthermore, we have addressed the problem of incompatibility of the enzymatic reaction and separation of the reactants. As a result, EMMA of native glycosidase was achieved with a reaction volume of ,,20 nL and the Michaelis constant was estimated according to the Lineweaver-Burk plot. The current method may have advantages over traditional assay methods, especially in terms of the amount of enzyme (ng order) and substrate (pmol order) required for a reaction*. [source] Characterization of ,- d -glucosidase extracted from soil fractionsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2000M. D. Busto Summary One way to study the state in which stabilized extracellular enzymes persist and are active in the soil is by extraction from the soil, with subsequent fractionation of enzyme,organomineral complexes and characterization of such complexes. In order to investigate the location and characteristics of soil ,-glucosidase, three soil fractions were obtained both from real (undisturbed) soil aggregates and from structural (dispersed in water and physically disrupted) aggregates using two different granulometric procedures. The ,-glucosidase activity of the fraction was then assayed. When the aggregates were dispersed, more than 73% of activity was in the soil microaggregates with diameters of less than 50 ,m (SF50). These aggregates were associated with strongly humified organic matter. Solutions of diluted pyrophosphate at neutral pH liberated active ,-glucosidase from all fractions, although the efficacy of extraction varied according to the type of fraction. The SF50 fraction and aggregates of 2000,100 ,m obtained by sieving (SF2000) showed the greatest ,-glucosidase activity (34.5 and 36.0%, respectively). Micro- and ultrafiltration of SF50 extracts increased the total ,-glucosidase activity, whereas these procedures, applied to the RF2000 fraction, decreased it. Humus,,-glucosidase complexes in the SF50 fraction, between 0.45 ,m and 105 nominal molecular weight limit ( nmwl) (SF50II) and < 105nmwl (SF50III) showed an optimum pH at 5.4, and in the SF50I fraction (> 0.45 ,m) the optimum was 4.0. The stability of ,-glucosidase in the aggregates of the smallest size SF50II and SF50III decreased at acid pHs. The presence of two enzymes (or two forms of the same enzyme) catalysing the same reaction with different values of Michaelis constant and maximum velocity was observed in all but one of the ,-glucosidase complexes extracted and partially purified from the SF50 aggregates. [source] Inhibition of recombinant human maltase glucoamylase by salacinol and derivativesFEBS JOURNAL, Issue 12 2006Elena J. Rossi Inhibitors targeting pancreatic ,-amylase and intestinal ,-glucosidases delay glucose production following digestion and are currently used in the treatment of Type II diabetes. Maltase-glucoamylase (MGA), a family 31 glycoside hydrolase, is an ,-glucosidase anchored in the membrane of small intestinal epithelial cells responsible for the final step of mammalian starch digestion leading to the release of glucose. This paper reports the production and purification of active human recombinant MGA amino terminal catalytic domain (MGAnt) from two different eukaryotic cell culture systems. MGAnt overexpressed in Drosophila cells was of quality and quantity suitable for kinetic and inhibition studies as well as future structural studies. Inhibition of MGAnt was tested with a group of prospective ,-glucosidase inhibitors modeled after salacinol, a naturally occurring ,-glucosidase inhibitor, and acarbose, a currently prescribed antidiabetic agent. Four synthetic inhibitors that bind and inhibit MGAnt activity better than acarbose, and at comparable levels to salacinol, were found. The inhibitors are derivatives of salacinol that contain either a selenium atom in place of sulfur in the five-membered ring, or a longer polyhydroxylated, sulfated chain than salacinol. Six-membered ring derivatives of salacinol and compounds modeled after miglitol were much less effective as MGAnt inhibitors. These results provide information on the inhibitory profile of MGAnt that will guide the development of new compounds having antidiabetic activity. [source] Heterologous expression of a Rauvolfia cDNA encoding strictosidine glucosidase, a biosynthetic key to over 2000 monoterpenoid indole alkaloidsFEBS JOURNAL, Issue 8 2002Irina Gerasimenko Strictosidine glucosidase (SG) is an enzyme that catalyses the second step in the biosynthesis of various classes of monoterpenoid indole alkaloids. Based on the comparison of cDNA sequences of SG from Catharanthus roseus and raucaffricine glucosidase (RG) from Rauvolfia serpentina, primers for RT-PCR were designed and the cDNA encoding SG was cloned from R. serpentina cell suspension cultures. The active enzyme was expressed in Escherichia coli and purified to homogeneity. Analysis of its deduced amino-acid sequence assigned the SG from R. serpentina to family 1 of glycosyl hydrolases. In contrast to the SG from C. roseus, the enzyme from R. serpentina is predicted to lack an uncleavable N-terminal signal sequence, which is believed to direct proteins to the endoplasmic reticulum. The temperature and pH optimum, enzyme kinetic parameters and substrate specificity of the heterologously expressed SG were studied and compared to those of the C. roseus enzyme, revealing some differences between the two glucosidases. In vitro deglucosylation of strictosidine by R. serpentina SG proceeds by the same mechanism as has been shown for the C. roseus enzyme preparation. The reaction gives rise to the end product cathenamine and involves 4,21-dehydrocorynantheine aldehyde as an intermediate. The enzymatic hydrolysis of dolichantoside (N,-methylstrictosidine) leads to several products. One of them was identified as a new compound, 3-isocorreantine A. From the data it can be concluded that the divergence of the biosynthetic pathways leading to different classes of indole alkaloids formed in R. serpentina and C. roseus cell suspension cultures occurs at a later stage than strictosidine deglucosylation. [source] Functional microbial community response to nutrient pulses by artificial groundwater recharge practice in surface soils and subsoilsFEMS MICROBIOLOGY ECOLOGY, Issue 3 2010Kirsten Schütz Abstract Subsurface microorganisms are essential constituents of the soil purification processes associated with groundwater quality. In particular, soil enzyme activity determines the biodegradation of organic compounds passing through the soil profile. Transects from surface soil to a depth of 3.5 m were investigated for microbial and chemical soil characteristics at two groundwater recharge sites and one control site. The functional diversity of the microbial community was analyzed via the activity of eight enzymes. Acid phosphomonoesterase was dominant across sites and depths, followed by l -leucine aminopeptidase and ,-glucosidase. Structural [e.g. phospholipid fatty acid (PLFA) pattern] and functional microbial diversities were linked to each other at the nonwatered site, whereas amendment with nutrients (DOC, NO3,) by flooding uncoupled this relationship. Microbial biomass did not differ between sites, whereas microbial respiration was the highest at the watered sites. Hence, excess nutrients available due to artificial groundwater recharge could not compensate for the limitation by others (e.g. phosphorus as assigned by acid phosphomonoesterase activity). Instead, at a similar microbial biomass, waste respiration via overflow metabolism occurred. In summary, ample supply of carbon by flooding led to a separation of decomposition and microbial growth, which may play an important role in regulating purification processes during groundwater recharge. [source] Effect of fermentation on free and bound volatile compounds of orange juiceFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2009Gang Fan Abstract Aroma is one of the most important attributes of orange wine quality. The volatile compounds in orange wine mainly derive from oranges, yeast fermentation and compounds released from odourless glycosidic precursors present in the orange. In this study, free volatile compounds in orange juice and wine made from Citrus sinensis (L). Osbeck cv. Washington Sanguine were analysed by SPME-GC,MS. Bound fractions were isolated and extracted with methanol and Amberlite XAD-2 resin and then hydrolysed by almond , -glucosidase. Totals of 31 and 19 free volatiles were identified in orange juice and wines, respectively. Terpenes were the most abundant compounds in orange juice, while esters were quantitatively the dominant group in orange wine and most of them were compounds newly formed during fermentation, such as isoamyl acetate, ethyl hexanoate, ethyl benzoate, diethyl succinate, ethyl decanoate and ethyl laurate. In total, 11 and three released bound volatiles were found in orange juice and wine, respectively, and most of them were not found in free form. Only ethyl 3-hydroxyhexanoate and cis -carveol were found present in both the free and bound forms of orange juice. Copyright © 2009 John Wiley & Sons, Ltd. [source] Chemical composition and biological activities of the essential oils of Salvia canariensisFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2006M. C. García Vallejo Abstract Comparative studies of the chemical composition of steam-distilled essential oils from cultivated Salvia canariensis, collected at different seasons of the year, were studied. The essential oils were analysed by gas chomatography,mass spectrometry: the major components were bornyl acetate (17.8,28.6%), , -caryophyllene (12.7,30.2%), , -pinene (4.6,9.5%) and viridiflorol (13.9,17.3%) in all samples. The essential oils were evaluated for antimicrobial and cytostatic activities and enzymatic inhibitions of xanthine oxidase, , -glucosidase and , -glucuronidase. Concerning the antimicrobial and cytotoxic tests, the oils showed interesting activities towards different Gram-positive bacteria (MIC 45,35 µg[sol ]ml), but had no effect against eukaryotic cells. Copyright © 2005 John Wiley & Sons, Ltd. [source] Volatile constituents of different organs of Psoralea bituminosa L.FLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2004Alessandra Bertoli Abstract The essential oil and SPME samples of the leaves, ,owers and seeds of Psoralea bituminosa L. were analysed by GC and GC,MS. We have investigated also the presence of monoterpene or aliphatic alcohol glucosides. The essential oils showed both qualitative and quantitative differences. The main constituents of the leaf and the ,ower essential oils were caryophyllene (23% and 18%, respectively), , -farnesene (15% and 6%, respectively), and germacrene D (24% and 18%, respectively). Signi,cant amounts (7%) of the same compounds were also directed in the seed essential oil, but tricyclene (11%) and , -pinene (50%) were the most important constituents of this oil. The volatile fractions of remaining leaf aqueous extracts after treatment with , -glucosidase revealed qualitative differences in comparison with the composition of the corresponding essential oils, and high levels of 3-hexen-1-ol (37%) and 1-octen-3-ol (27%) were observed. The SPME analysis of the fresh leaves, ,owers and seeds of P. bituminosa con,rmed the qualitative composition of the volatile oils, even if we detected signi,cative differences in the percentage ratio between monoterpenes and sesquiterpenes in comparison with the oils, where sesquiterpenes were the main components. In fact the variation of the monoterpenes, tricyclene, , -pinene and camphene between the leaf oil and the corresponding headspace sample was remarkable: tricyclene increased from 0.1% to 8%, , -pinene from 0.1% to 16% and camphene from 0.3% to 10% in the SPME samples. Copyright © 2004 John Wiley & Sons, Ltd. [source] Starch-like exopolysaccharide produced by the filamentous fungi Ophiostoma ulmi and O. novo-ulmiFOREST PATHOLOGY, Issue 2 2007R. Jeng Summary This paper describes the chemical and biochemical properties of exopolysaccharides (EPS) produced by Ophiostoma ulmi and O. novo-ulmi isolates, the Dutch elm disease (DED) fungi. Some of EPS have been considered as pathogenicity factor in the DED complex. The selected isolates grow well and produce EPS in a medium containing various types of carbon and nitrogen sources. EPS obtained from potato dextrose broth (PDB) medium appeared to be opaque, firm and stained purple blue with iodine-potassium iodide solution, whereas those from yeast extract (YE) medium were less opaque, jelly-like and remained unchanged in iodine solution. The selected fungal isolates produced much higher molecular weight EPS from the medium containing YE than from PDB. The results of this study suggest that high molecular weight compounds produced by O. ulmi (W9) and O. novo-ulmi (R136) are not involved in DED pathogenesis. Spectrometric analysis of acid-digested EPS obtained from PDB and YE revealed the presence of a monomer similar to glucose used as a standard. Thin layer chromatography indicated that glucan-1,4- , -glucosidase (glucoamylase) only hydrolyses EPS from PDB media and releases glucose. The results strongly indicate that isolates of O. ulmi and O. novo-ulmi produce starch-like EPS from PDB medium. The EPS obtained from YE medium lacked this characteristic. The biological significance and the potential use of these EPS are discussed. [source] Exoenzyme activities as indicators of dissolved organic matter composition in the hyporheic zone of a floodplain riverFRESHWATER BIOLOGY, Issue 8 2010SANDRA M. CLINTON Summary 1. We measured the hyporheic microbial exoenzyme activities in a floodplain river to determine whether dissolved organic matter (DOM) bioavailability varied with overlying riparian vegetation patch structure or position along flowpaths. 2. Particulate organic matter (POM), dissolved organic carbon (DOC), dissolved oxygen (DO), electrical conductivity and temperature were sampled from wells in a riparian terrace on the Queets River, Washington, U.S.A. on 25 March, 15 May, 20 July and 09 October 1999. Dissolved nitrate, ammonium and soluble reactive phosphorus were also collected on 20 July and 09 October 1999. Wells were characterised by their associated overlying vegetation: bare cobble/young alder, mid-aged alder (8,20 years) and old alder/old-growth conifer (25 to >100 years). POM was analysed for the ash-free dry mass and the activities of eight exoenzymes (,-glucosidase, ,-glucosidase, , -N-acetylglucosaminidase, xylosidase, phosphatase, leucine aminopeptidase, esterase and endopeptidase) using fluorogenic substrates. 3. Exoenzyme activities in the Queets River hyporheic zone indicated the presence of an active microbial community metabolising a diverse array of organic molecules. Individual exoenzyme activity (mean ± standard error) ranged from 0.507 ± 0.1547 to 22.8 ± 5.69 ,mol MUF (g AFDM),1 h,1, was highly variable among wells and varied seasonally, with the lowest rates occurring in March. Exoenzyme activities were weakly correlated with DO, DOC and inorganic nutrient concentrations. 4. Ratios of leucine aminopeptidase : ,-glucosidase were low in March, May and October and high in July, potentially indicating a switch from polysaccharides to proteins as the dominant component of microbial metabolism. 5. Principal components analysis indicated that there were patch effects and that these effects were strongest in the summer. 6. DOM degradation patterns did not change systematically along hyporheic flowpaths but varied with overlying forest patch type in the Queets River hyporheic zone, suggesting that additional carbon inputs exist. We hypothesise that the most likely input is the downward movement of DOM from overlying riparian soils. Understanding this movement of DOM from soils to subsurface water is essential for understanding both the hyporheic metabolism and the carbon budget of streams and rivers. [source] Interactions between fauna and sediment control the breakdown of plant matter in river sedimentsFRESHWATER BIOLOGY, Issue 4 2010SIMON NAVEL Summary 1. A substantial portion of particulate organic matter (POM) is stored in the sediment of rivers and streams. Leaf litter breakdown as an ecosystem process mediated by microorganisms and invertebrates is well documented in surface waters. In contrast, this process and especially the implication for invertebrates in subsurface environments remain poorly studied. 2. In the hyporheic zone, sediment grain size distribution exerts a strong influence on hydrodynamics and habitability for invertebrates. We expected that the influence of shredders on organic matter breakdown in river sediments would be influenced strongly by the physical structure of the interstitial habitat. 3. To test this hypothesis, the influence of gammarids (shredders commonly encountered in the hyporheos) on degradation of buried leaf litter was measured in experimental systems (slow filtration columns). We manipulated the structure of the sedimentary habitat by addition of sand to a gravel-based sediment column to reproduce three conditions of accessible pore volume. Ten gammarids were introduced in columns together with litter bags containing alder leaves at a depth of 8 cm in sediment. Leaves were collected after 28 days to determine leaf mass loss and associated microbial activity (fungal biomass, bacterial abundance and glucosidase, xylosidase and aminopeptidase activities). 4. As predicted, the consumption of buried leaf litter by shredders was strongly influenced by the sediment structure. Effective porosity of 35% and 25% allowed the access to buried leaf litter for gammarids, whereas a lower porosity (12%) did not. As a consequence, leaf litter breakdown rates in columns with 35% and 25% effective porosity were twice as high as in the 12% condition. Microbial activity was poorly stimulated by gammarids, suggesting a low microbial contribution to leaf mass loss and a direct effect of gammarids through feeding activity. 5. Our results show that breakdown of POM in subsurface waters depends on the accessibility of food patches to shredders. [source] Lysosomal abnormalities during benzo(a)pyrene-induced experimental lung carcinogenesis , defensive role of capsaicinFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 1 2009P. Anandakumar Abstract The objective of the present study was to investigate whether lysosome is a target in benzo(a)pyrene-induced, oxidative stress-mediated lung cancer in Swiss albino mice and the plausible role of the phytochemical substance capsaicin in mitigating lysosomal damage. Oxidative stress was assessed based on the level of carbonyl content. The activities of lysosomal proteases like cathepsin-D, cathepsin-B, ,- d -glucosidase, ,- d -galactosidase, ,- d -glucuronidase, ,- d - N -acetylglucosaminidase and acid phosphatase were assessed to evaluate lysosomal function. Administration of benzo(a)pyrene (50 mg/kg body weight) to mice induced a increase in the activities of lysosomal enzymes and oxidative stress was evident by the increase in carbonyl content. Treatment with capsaicin (10 mg/kg body weight) decreased carbonyl content and restored the activities of lysosomal enzymes to near normalcy. Transmission electron microscopic study of lysosomes further showed the defensive action of capsaicin against the lysosomal damage caused in benzo(a)pyrene-induced lung cancer. From the present study, it can be concluded that lysosomal damage is an indispensable event in benzo(a)pyrene-induced lung cancer, and capsaicin was able to effectively prevent it, which proves the chemoprotective effect of capsaicin against benzo(a)pyrene-induced experimental lung carcinogenesis. [source] Seasonal variation in enzyme activities and temperature sensitivities in Arctic tundra soilsGLOBAL CHANGE BIOLOGY, Issue 7 2009MATTHEW D. WALLENSTEIN Abstract Arctic soils contain large amounts of organic matter due to very slow rates of detritus decomposition. The first step in decomposition results from the activity of extracellular enzymes produced by soil microbes. We hypothesized that potential enzyme activities are low relative to the large stocks of organic matter in Arctic tundra soils, and that enzyme activity is low at in situ temperatures. We measured the potential activity of six hydrolytic enzymes at 4 and 20 °C on four sampling dates in tussock, intertussock, shrub organic, and shrub mineral soils at Toolik Lake, Alaska. Potential activities of N -acetyl glucosaminidase, ,-glucosidase, and peptidase tended to be greatest at the end of winter, suggesting that microbes produced enzymes while soils were frozen. In general, enzyme activities did not increase during the Arctic summer, suggesting that enzyme production is N-limited during the period when temperatures would otherwise drive higher enzyme activity in situ. We also detected seasonal variations in the temperature sensitivity (Q10) of soil enzymes. In general, soil enzyme pools were more sensitive to temperature at the end of the winter than during the summer. We modeled potential in situ,-glucosidase activities for tussock and shrub organic soils based on measured enzyme activities, temperature sensitivities, and daily soil temperature data. Modeled in situ enzyme activity in tussock soils increased briefly during the spring, then declined through the summer. In shrub soils, modeled enzyme activities increased through the spring thaw into early August, and then declined through the late summer and into winter. Overall, temperature is the strongest factor driving low in situ enzyme activities in the Arctic. However, enzyme activity was low during the summer, possibly due to N-limitation of enzyme production, which would constrain enzyme activity during the brief period when temperatures would otherwise drive higher rates of decomposition. [source] Three New Benzophenone Glucosides from the Leaves of Planchonella obovataHELVETICA CHIMICA ACTA, Issue 3 2010Shoei-Sheng Lee Abstract Chemical investigation of the EtOH extract of the leaves of Planchonella obovata resulted in the isolation of four benzophenone glucosides, 1,4, of which three, 2,4, are new chemical entities together with five known flavonol glycosides. Their structures were elucidated by spectroscopic analysis. Among the isolated compounds, iriflophenone 2- O -(2,6-di- O -galloyl)- , - D -glucopyranoside (4) showed some activity (91.4 and 15.0% inhibition at 100 and 10,,g/ml, resp.) against the , -glucosidase of Bacillus stearothermophilus. [source] Norbornane Mimics of Distorted , - D -Glucopyranosides , Inhibitors of , - D -Glucopyranosidases?HELVETICA CHIMICA ACTA, Issue 4 2006Stephan Buser Abstract The racemic gluco -configured norbornanes 4 and 16 were prepared and tested as inhibitors of ,- glucosidases. The known alcohol 5 was deprotected to provide the triol 6. Silylation (,,7), monobenzoylation (,,8/9), and oxidation provided the regioisomeric ketones 10 and 11. Reduction of 10 gave the desired endo -alcohol 13, albeit in low yield, while reduction of the isomeric ketone 11 provided mostly the altro -configured endo -alcohol 12. The alcohol 13 was desilylated to 14. Debenzoylation to 15 followed by hydrogenolytic deprotection gave the amino triol 4 that was reductively aminated to the benzylamine 16. The amino triols 4 and 16 proved weak inhibitors of the , -glucosidase from Caldocellum saccharolyticum (4: IC50,=,5.6,mm; 16:IC50,=,3.3,mm) and from sweet,almonds (16:IC50,=,5.5,mm). A comparison of 4 with the manno -configured norbornane 3 shows that 3 is a better inhibitor of snail , -mannosidase than 4 is of ,- glucosidases, in keeping with earlier results suggesting that these , -glycosidases enforce a different conformational itinerary. [source] Synthesis of 2-Azabicyclo[3.2.2]nonane-Derived Monosaccharide Mimics and Their Evaluation as Glycosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 3 2006Stephan Buser Abstract The racemic 2-azabicyclo[3.2.2]nonanes 5 and 18 were synthesized and tested as , -glycosidase inhibitors. The intramolecular Diels,Alder reaction of the masked o -benzoquinone generated from 2-(allyloxy)phenol (6) gave the , -keto acetal 7 which was reduced with SmI2 to the hydroxy ketone 8. Dihydroxylation, isopropylidenation (,,12), and Beckmann rearrangement provided lactam 15. N -Benzylation of this lactam, reduction to the amine 17, and deprotection provided the amino triol 19 which was debenzylated to the secondary amine 5. Both 5 and 19 proved weak inhibitors of snail , -mannosidase (IC50,>,10,mM), Caldocellum saccharolyticum , -glucosidase (IC50,>,10,mM), sweet almond , -glucosidase (IC50,>,10,mM), yeast , -glucosidase (5: IC50,>,10,mM; 19: IC50,=,1.2,mM), and Jack bean , -mannosidase (no inhibition detected). [source] Synthesis of New C(2) -Substituted gluco -Configured Tetrahydroimidazopyridines and Their Evaluation as Glucosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 10 2005Bhagavathy Shanmugasundaram The gluco -configured C(2) -substituted tetrahydroimidazopyridines 8,14 were prepared and tested as inhibitors of the , -glucosidases from Caldocellum saccharolyticum and from sweet almonds, and of the , -glucosidase from brewer's yeast. All new imidazopyridines are nanomolar inhibitors of the , -glucosidases and micromolar inhibitors of the , -glucosidase. The 3-phenylpropyl derivative 14 proved the strongest inhibitor of the Caldocellum , -glucosidase (Ki,=,0.9,nM), only slightly weaker than the known 2-phenylethyl analogue 7, and the propyl derivative 13 is the strongest inhibitor of the sweet almond , -glucosidases (Ki,=,3.2,nM), again slightly weaker than 7. There is no strong dependence of the inhibition on the nature of the C(2) -substituent and no clear correlation between the inhibitory strength of the known manno -configured imidazopyridines 2,6 and the gluco -analogues 8,12. While most manno -imidazopyridines are competitive inhibitors, the gluco -analogues proved non-competitive inhibitors of the Caldocellum , -glucosidase and mixed-type or partial mixed-type inhibitors of the sweet almond , -glucosidases. [source] Synthesis of N -Acetylglucosamine-Derived Nagstatin Analogues and Their Evaluation as Glycosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 1 2005Miroslav Terinek The gluco -configured analogue 15 of nagstatin (1) and the methyl ester 14 were synthesized via condensation of the thionolactams 17 or 18 with the , -amino ester 19. The silyl ethers 20 and 21 resulting from 17 were desilylated to 22 and 23; these alcohols were directly obtained by condensing 18 and 19. The attempted substitution of the C(8)OH group of 22 by azide under Mitsunobu conditions led unexpectedly to the deoxygenated , -azido esters 24. The desired azide 25 was obtained by treating the manno -configured alcohol 23 with diphenyl phosphorazidate. The azide was transformed to the debenzylated acetamido ester 14 that was hydrolyzed to the nagstatin analogue 15. The imidazole-2-acetates 14 and 15 are nanomolar inhibitors of the N -acetyl- , -glucosaminidases from Jack beans and from bovine kidney, submicromolar to micromolar inhibitors of the , -glucosidase from Caldocellum saccharolyticum, and rather weak inhibitors of the snail , -mannosidase. In all cases, the ester was a stronger inhibitor than the corresponding acid. As expected from their gluco -configuration, both imidazopyridines 14 and 15 are stronger inhibitors of the , - N -acetylglucosaminidase from bovine kidney than nagstatin. [source] Pakistolides A and B, Novel Enzyme Inhibitory and Antioxidant Dimeric 4-(Glucosyloxy)Benzoates from Berchemia pakistanicaHELVETICA CHIMICA ACTA, Issue 2 2004Naveen Mukhtar Pakistolides A and B, novel dimeric , -(glucosyloxy)benzoates were isolated from Berchemia pakistanica and assigned structures 1 and 2 on the basis of extensive NMR studies. In addition, the known compounds 7,5,-dimethoxy-3,5,2,-trihydroxyflavone (=3,5-dihydroxy-2-(2-hydroxy-5-methoxyphenyl)-7-methoxy-4H -1-benzopyran-4-one), 4,,5-dihydroxy-3,6,7-trimethoxyflavone (=5-hydroxy-2-(4-hydroxyphenyl)-3,6,7-trimethoxy-4H -1-benzopyran-4-one), 5,6-dihydroxy-4,7-dimethoxy-2-methylanthracene-9,10-dione, and 1,3,4-trihydroxy-6,7,8-trimethoxy-2-methylanthracene-9,10-dione were reported for the first time from the genus Berchemia. Both 1 and 2 showed significant , -glucosidase and lipoxygenase inhibitory activities, while 2 also showed antioxidant potential. [source] | |||||||||||||||||||||||||||||||