Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 149-155).

Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Xylanolytic accessory enzymes produced by the endo-p-l,4-xylanase overproducing, colour-variant strain of the euascomycetous fungus Aureobasidium pullulans, NRRL Y-2311-1, were studied. a- Glucuronidase activity was only induced during cultivation on carbon sources containing both xylose and glucuronic acid. An a-glucuronidase was partially purified from the supernatant of A. pullulans cultivated on birchwood glucuronoxylan. The enzyme had an apparent mobility on SDS-PAGE of 170 kDa, and after deglycosylation its mobility shifted to 118 kDa, indicating an extensively decorated protein. Maximal activity was measured at pH 3 in McIlvaine's phosphate-citrate buffer and at 40°C, and the enzyme was stable for 3 h at 40°C. The enzyme displayed substrate inhibition, and Km- and Kj-values were calculated as 3.3 ± 0.29 mM and 9.8 ± 3.8 mM for aldotriouronic acid and 29.5 ± 7.6 mM and 29.0 ± 7.8 for aldobiouronic acid respectively. PCR methods were used to clone the genes encoding an a-glucuronidase and an a-Larabinofuranosidase of A. pullulans NRRL Y-2311-1. The deduced amino acid sequence of the aglucuronidase encoding gene, aguA, shared greater than 60% identity with fungal glucuronidases and between 34% and 42% identity with bacterial a-glucuronidases, and it is member of family 67 of the glycoside hydrolases. The aguA gene encodes a protein of 836 amino acids with a putative secretion signal of 15 amino acids, resulting in a mature protein with a predicted molecular weight of 91 kDa. The gene was expressed in S. cerevisiae Y294 under control of the ADH2 promoter and terminator. The heterologous a-glucuronidase was purified to homogeneity using Ni-chelate affinity chromatography, and it had an electrophoretic mobility of 120 kDa on SDS-PAGE. The enzyme was maximally active at 65°C and between pH 5 and pH 6. The enzyme was stable at 45°C, lost half of its activity after 22.5 minutes at 55°C, and had a half-life of 5.6 min at 65 °C. It was stable at pH 4 and pH 6, and had a half-life of 17 min at pH 8. The enzyme had Km-values in the millimolar range for the series from aldobiouronic acid to aldopentaouronic acid. It had the highest catalytic efficiency on aldobiouronic acid and the catalytic efficiency decreased with increasing chain-length of the oligosaccharide substrate. The deduced amino acid sequence of the a-L-arabinofuranosidase gene, ab/A, shared between 69% and 76% identity with family 54 c-arabinofuranosidases. The gene encodes a polypeptide of 498 amino acids with a putative signal peptide of 20 amino acids resulting in a mature protein with a calculated molecular weight of 49.9 kDa. It was expressed in S. cerevisiae Y294 and the heterologous enzyme was purified to homogeneity by gel filtration. It's size estimated by gel filtration was 36 kDa, and it had an apparent mobility of 49 kDa on SDS-PAGE. It showed maximal activity at 55°C and between pH 3.5 and pH 4. It was stable at 50°C and between pH 4 and pH 5. The enzyme had a Km for p-nitrophenyl c-arabinofuranoside of 3.7 ± 0.36 mM and a Vrnax of 34.8 ± 1.1 U/mg protein. It displayed 0.2 U/mg activity against p-nitrophenyl ~-xylopyranoside. / AFRIKAANSE OPSOMMING: Hierdie studie het gefokus op xilanolitiese ensieme van die endo-I3-1,4-xilanase oorproduserende, kleur-variante ras van die euaskomiseet Aureobasidium pullulans, NRRL Y-2311-1. 0:- Glukuronidase-aktiwiteit is slegs geïnduseer tydens groei op koolstofbronne wat beide xilose en glukuronsuur bevat. u-Glukuronidase is gedeeltelik uit die supernatant van A. pullulans gekweek op berkehout glukuronoxilaan gesuiwer. Die ensiem se elekroforetiese mobiliteit met SDS-PAGE was 170 kDa en na deglikosilering het dit verskuif na 118 kDa, beduidend van 'n swaar geglikosileerde ensiem. Maksimum aktiwiteit is gemeet by pH 3 in McIlvaine se sitraat-fosfaat buffer en by 40°C. Die ensiem was stabiel by 40°C tydens 'n 3-uur inkubasie. Substraat inhibisie is bespeur, en die ensiem se Km- en Kj-waardes vir aldotriouronsuur was onderskeidelik 3.3 ± 0.29 mM en 9.8 ± 3.8 mM en vir aldobiouronsuur was die waardes onderskeidelik 29.5 ± 7.6 mM en 29.0 ± 7.8 mM. PKR metodes is benut om die gene vir u-glukuronidase en cc-arabinofuranosidase te kloneer. Die afgeleide aminosuurvolgorde van die c-glukuronidase geen, aguA, was meer as 60% identies aan swam cc-glukuronidases, en tussen 34% en 42% identies aan bakteriële u-glukuronidases, en dit is 'n lid van familie 67 van die glikosied hidrolases. Die aguA geen kodeer vir 'n proteïen van 836 amienosure met 'n sekresiesein van 15 amienosure, wat die produksie van 'n volwasse protein met 'n molekulêre gewig van 91 kDa tot gevolg het. Die geen is uitgedruk in S. cerevisiae Y294 onder beheer van die ADH2 promoter en termineerder. Ni-chelaat affiniteitschromatografie is gebruik om die heteroloë cc-glukuronidase te suiwer. Die elektroforetiese mobiliteit van die suiwer ensiem was 120 kDa met SDS-PAGE. Die ensiem het maksimale aktiwiteit by 65°C en tussen pH 5 en pH 6 getoon. Die ensiem was stabiel vir twee ure by 45°C, het die helfte van sy aktiwiteit binne 22.5 minute by 55°C verloor, en het 'n halfleeftyd van 5.6 minute by 65°C gehad. Dit was stabiel by pH 4 en pH 6 vir twee ure, en het 'n halfleeftyd van 17 minute by pH 8 gehad. Die ensiem het millimolaar Km-waardes getoon vir die substraatreeks vanaf aldobiouronsuur tot aldopentaouronsuur. Dit het die hoogste katalitiese effektiwiteit vir aldobiuronsuur gehad en die katalitiese effektiwiteit het afgeneem met toenemende lengte van die oligosakkaried substraat. Die afgeleide amienosuurvolgorde van die c-t-arabinofuranosidase geen, abfA, was tussen 69% en 76% identies aan familie 54 u-t-arabinofuranosidases. Die geen kodeer vir 'n proteïen van 498 amienosure met 'n seinpeptied van 20 aminosure, wat lei tot die produksie van 'n volwasse proteïen met 'n berekende molekulêre massa van 49.9 kDa. Die geen is uitgedruk in S. cerevisiae Y294 en die heteroloë ensiem is gesuiwer deur gel filtrasie. Die ensiem se geskatte molekulêre gewig met gel filtrasie was 36 kDa, en die ensiem se mobiliteit op SDS-PAGE was 49 kDa. Dit het maksimum aktiwiteit getoon by 55°C, en tussen pH 3.5 en pH 4. Dit was stabiel vir twee ure by 50°C en tussen pH 4 en pH 5. Die ensiem se Km vir p-nitrofeniel c-t-arabinofuranosied was 3.7 ± 0.36 mM en die Vmax was 34.8 ± 1.1 U/mg proteïen. Die ensiem het aktiwiteit teen p-nitrofenie1 I3-D-xilopiranosied van 0.2 U/mg getoon.

No description available.

Thesis (M.Sc.). / Written for the Dept. of Plant Science. Title from title page of PDF (viewed 2008/05/29). Includes bibliographical references.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12918号 / 論医博第2093号 / 新制||医||1009(附属図書館) / 32128 / (主査)教授 羽賀 博典, 教授 中川 一路, 教授 上杉 志成 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

**Problématique :** L'accumulation excessive des acides biliaires (AB) est incriminée dans la pathogénie de plusieurs maladies hépatiques et intestinales. Il a été démontré que la β-glucuronidation hépatique favorise l'élimination et la détoxification des AB. Cependant, l'action des enzymes β-glucuronidase (GUS) de la flore intestinale contrecarre ce processus d'inactivation. **Objectif :** Mettre en évidence l'action des enzymes GUS du microbiote intestinal sur les acides biliaires glucuronoconjugués (AB-G) et la possibilité du moduler cette action par des interventions nutritionnelles et pharmacologiques. **Méthodes :** Des essais enzymatiques *in vitro* dans des conditions expérimentales adaptées ont été réalisés sur différents groupes d'échantillons de fèces humaines, incluant des individus sains, des individus atteints de maladies hépatiques, ainsi que des échantillons de selles et contenus intestinaux de souris axéniques et conventionnelles, et des crottes de rats après diverses chirurgies bariatriques. De plus, deux molécules amoxapine et inhibiteur 1 de la β-glucuronidase ont été utilisés pour explorer *in vitro* leurs effets en tant qu'inhibiteurs GUS sur la réaction GUS-AB-G. En outre, l'effet d'une supplémentation de 50g/j de poudre de bleuet lyophilisée (PBL) pendant 8 semaines chez des adultes humains (n=24) sur cette réaction a également été caractérisé. **Résultats :** Le microbiote intestinal GUS (β-glucuronidase), provenant des échantillons testés, a la capacité de déconjuguer les AB-G avec des variations entre individus, entre genres et entre espèces. Les acides biliaires glucuronidés en position 24 (AB-24G) sont déconjugués de manière plus efficace que leurs analogues en position 3 et 6 (AB-3G, AB-6G). *In vitro* l'amoxapine a montré une inhibition plus marquée des enzymes GUS *d'E.coli*, humains et murins que l'inhibiteur 1 de la β-glucuronidase, avec une IC50 de 34.74 ±1.09 µM (IC50 ± SD) pour GUS d'*E.coli* envers β-MCA-24G. La supplémentation par PBL a diminué de manière significative (p<0.01) l'activité GUS envers les AB-G mais uniquement chez les hommes avec des changements dans les valeurs de Km et Vmax. **Conclusion :** Nos résultats confirment le rôle des enzymes GUS du microbiote intestinal dans la retoxification des AB et révèlent la possibilité de moduler cette activité. Cette modulation pourrait contribuer à établir ces enzymes comme une nouvelle cible pour potentialiser l'effet détoxifiant de la glucuronidation envers les AB et réduire leur toxicité. / **Background:** Excessive accumulation of bile acids (BA) is implicated in the pathogenesis of many hepatic and intestinal diseases. Hepatic glucuronidation has been shown to promote the elimination and detoxification of BA. However, the action of β-glucuronidase (GUS) enzymes in the intestinal flora counteracts this inactivation process. **Objective:** To demonstrate the action of GUS enzymes in the intestinal microbiota on bile acid glucuronides (BA-G) and the possibility of modulating this action through nutritional and pharmacological interventions. **Methods:** *In vitro* enzymatic assays under adapted experimental conditions were performed on different groups of human fecal samples, including healthy individuals, individuals with liver diseases, as well as stool samples and intestinal contents from germ-free and conventional mice, and rats fecal samples after various bariatric surgeries. Additionally, two molecules, amoxapine and β-glucuronidase inhibitor 1, were used to explore *in vitro* their effects as GUS inhibitors on the GUS-BA-G reaction. Furthermore, the impact of a supplementation of 50g/day of freeze-dried highbush blueberry powder (BBP) for 8 weeks in adult humans (n=24) on this reaction was also characterized. **Results:** The GUS (β-glucuronidase) enzymes of intestinal microbiota from the samples tested efficiently deconjugate BA-G with variations between individuals, genera, and species. Bile acid glucuronides at position 24 (BA-24G) are deconjugated more efficiently than their analogues at positions 3 and 6 (BA-3G, BA-6G). *In vitro*, amoxapine showed more marked inhibition of human, murine and *E.coli* GUS enzymes than β-glucuronidase inhibitor 1, with an IC50 of 34.74 ±1.09 µM (IC50 ± SD) for *E.coli* GUS towards β-MCA-24G. BBP supplementation significantly (p<0.01) decreased GUS activity towards BA-G but only in males with changes in Km and Vmax values. **Conclusion:** Our results confirm the role of β-glucuronidase (GUS) enzymes from the intestinal microbiota in the re-toxification of BA and reveal the potential to modulate this activity. This modulation could help establish these enzymes as a new target to enhance the detoxifying effect of glucuronidation towards BA and reduce their toxicity.

Résumé : La prééclampsie (PE) est un désordre de la grossesse caractérisée par une dysfonction endothéliale faisant en sorte que l’endothélium devient moins sensible aux signaux de vasodilatation. La réponse provoquée par la liaison de la sérotonine au sous-type de récepteur S[indice inférieur 2] entraîne la libération de molécules aux propriétés vasoconstrictrices, qui, par une boucle de rétroaction positive, entraîne la libération de davantage de sérotonine par les plaquettes. Cette boucle amplifie la réponse et contribue ainsi à l’hypertension présente chez les femmes ayant une PE. Précédemment, il a été démontré par notre laboratoire que le Bisphénol A (BPA) s’accumulait davantage dans le placenta des femmes avec PE en comparaison aux femmes normotensives. Cette accumulation pourrait découler d’une perturbation de sa métabolisation qui impliquerait notamment la β-glucuronidase (GUSB). Des études chez les animaux ont quant à elles démontré que le BPA pouvait inhiber l’activité de la monoamine oxydase (MAO) à forte dose. Nous avons étudié l’effet du BPA à faible concentration (10 ng/ml) sur la MAO-A des cellules placentaires et démontré que le BPA inhibait la MAO-A de façon significative sans affecter son expression protéique. Afin d’expliquer l’accumulation particulière du BPA chez les femmes PE, nous avons comparé l’activité spécifique et l’expression protéique de la β-glucuronidase (GUSB) placentaire en utilisant un devis cas-témoins. Une tendance non significative suggère que la GUSB pourrait partiellement contribuer à l’accumulation du BPA chez les femmes PE. Nous avons étudié la relation entre la concentration sérique maternelle de BPA et la concentration à laquelle le fœtus est exposé par régression linéaire et corrélation de Spearman. Un tel modèle ne pourrait être utilisé pour déterminer de façon quantitative l’exposition fœtale. En revanche, en vue de la forte corrélation entre ces deux variables, une haute concentration sérique maternelle de BPA devrait se refléter par une haute exposition fœtale. Cette corrélation implique aussi que le métabolisme placentaire ne joue pas un rôle significatif dans la protection du fœtus. Le BPA pourrait ainsi contribuer à l’hypertension chez les femmes PE présentant une dysfonction endothéliale en inhibant la MAO-A et ainsi, favorisant la hausse de sérotonine circulante. Cette étude suggère les bases d’un mécanisme par lequel le BPA s’accumulerait davantage chez les femmes PE et affecterait ainsi la MAO-A placentaire et potentiellement, la MAO-A fœtale vu ses propriétés physico-chimiques. / Abstract : Preeclampsia (PE) is an hypertensive disorder of pregnancy characterized by a generalized endothelial dysfunction where the response to vasodilatation signals is compromised. The binding of serotonin to its S[subscript 2] receptor subtype 2 releases vasoconstrictor molecules which, by a positive retroaction loop, stimulates the release of more serotonin from platelets. This positive retroaction loop stimulates the vasoconstriction of blood vessels and contributes to the hypertension in women with PE. Previously, we showed that Bisphenol A (BPA) accumulates more in the placenta of women with PE than in normotensive women. This accumulation may be the result of an impaired metabolization due to the action of the β-Glucuronidase (GUSB). Animal studies showed that BPA at high dose could lower the activity of the monoamine oxidase A (MAO-A), an enzyme implicated in the metabolism of serotonin. We studied the impact of BPA at low dose (10 ng/ml) in trophoblastic primary cells and showed that even at low dose, BPA can lower its activity without affecting the protein expression. To determine if GUSB could be the cause of the BPA accumulation in women with PE, we studied its activity and protein expression in placental biopsies from women with and without PE. A nonsignificant tendency showed that the GUSB activity and protein expression were higher in women with PE. To study the impact of placental metabolism in the fetal exposure, we studied the relation between maternal and fetal concentrations of BPA with linear regression analysis and Spearman’s correlation. We showed that maternal BPA could not precisely predict the fetal exposure and that the placental metabolism is probably limited in light of the strong correlation between both variables. This strong correlation also implied that high maternal exposure would result in high fetal exposure. This study shows that the accumulation of BPA in preeclamptic women could contribute to maternal hypertension by interacting with serotonin levels. This accumulation could partially be attributed to a higher GUSB, but other factors are probably implicated. The strong correlation between maternal and fetal exposure implies that the placental metabolism of BPA is limited and does not protect the fetus significantly. This study suggests the basis of a mechanism explaining the abnormal accumulation of BPA in the placenta in women with PE and its impact on the placental MAO-A and potentially, the foetal MAO-A because of its physico-chemical properties.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 149-154). Also available on the World Wide Web.

Tobacco has been studied as a host for producing recombinant therapeutic proteins on a large-scale, commercial basis. However, the proteins expressed in tobacco usually need to be purified to high yield and purity from large amounts of biomass in order for their production to be commercially viable. The methods needed to purify proteins from tobacco are very challenging and not well studied. The objective of this research was to develop a process for the purification of the acidic model protein, recombinant β-glucuronidase (rGUS), from transgenic tobacco leaf tissue to high yield and purity. Polyelectrolyte precipitation with polyethyleneimine (PEI) was identified as an initial purification step for purifying acidic recombinant proteins from tobacco. Polyethyleneimine precipitation allowed for high recovery and concentration of the target protein while removing large amounts of impurities from the initial extract. At dosages of 700-800 mg PEI/g total protein, nearly 100% of the rGUS activity was precipitated with generally more than 90% recovered from the pellet. In addition, more than 60% of the native tobacco proteins were removed in the process, resulting in a purification factor near 4. Recombinant GUS was further purified by a step of hydrophobic interaction chromatography (HIC) followed by a step of hydroxyapatite chromatography (HAC). The HIC step served to remove PEI and other contaminants such as nucleic acids that were accumulated during the precipitation step, while the HAC step served to separate rGUS from the remaining native tobacco proteins, most notably ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco). Nearly 40% of the initial rGUS activity was recovered as a near homogeneous fraction based on SDS-PAGE analysis after the three step process. The main steps used in this process are anticipated to be scalable and do not rely on affinity separations, making the process potentially applicable to a wide variety of acidic recombinant proteins expressed in tobacco as well as other leafy crops. / Master of Science