PDase II activity was determined using a synthetic substrate, the 2,4-dinitrophenyl ester of thymidine 3'-phosphate. The enzyme activity was estimated in fractions obtained by differential centrifugation of homogenates of epithelial cells fromt.the small intestinal mucosa of guinea pigs and rats. In guinea pig preparations PDase II occurred with highest specific activity in those fractions rich in succinate dehydrogenase and acid phosphatase. A lysosomal location for the guinea pig enzyme was indicated by its structure-linked latency and by its association with particles which underwent a characteristic decrease in equilibrium density when Triton WR-1339 was injected into the animals. With rat preparations a much greater proportion of the PDase II activity was found in the soluble fraction after uult-ra;c;entrifugation. The rat enzyme exhibited a lower degree of latency and administration of Triton WR-1339 had no effect. The rat enzyme activity in these crude preparations further differed from that of the guinea pig in other respects; it was more labile at 60°C, exhibited a slightly lower pH optimum, had a higher molecular weight as determined by gel filtration chromatography and displayed a much smaller tendency to aggregate under Llow salt conditions. Both enzymes were purified by chromatography on DEAE-cellulose, CM-cellulose and agarose, the extensive purification (550 fold) of the rat enzyme being largely due to its behaviour oh the latter material where it was found to bind tenaciously in low ionic strength solutions. On the other hand, only a fifteen-fold purification of the guinea pig enzyme was obtained because of its tendency tofform insoluble aggregatesdduring the chromatographic steps. In the main, the properties of the partially purified enzymes were quite similar. Both displayed pH optima between pH 6 and 7, were inhibited in solutions of high ionic strength, were unaffected' by divalent cations or EDTA, were similarly inactivated by heating at a temperature of 60°G displayed discontinuous Arrhenius plots _5 and exhibited Km values of the order 2-5x10 M for dTpDNP. In most casestfche differences between the enzymes were just differences of degree and could probably be accounted for byethe different extents to which the enzymes were purified. A more extensive characterization of the highly purified rat PDase was carried out. The fall-off in PDase II reaction rate observed at high enzyme levels with dTpDNP as substrate was found to be due to competitive inhibition of the enzyme by dTp, a reaction product which showed a of 2x10 M. The isoelectric point of PDase II was estimated by electrofocusing but since multiple peaks of activity were found at pH 3.4, 4.2-4.5, and pH 7.2 a conclusive result was not obtained. Polyacrylamide gel electrophoresis of purified rat PDase II indicated that the pattern obtained was, in part, dependent on whether the preparation was fresh or not; freshly purified PDase II contained up to 10 bands in gels stained for protein whereas only 1-2 bands were obtained when the preparations were "aged". A molecular weight of 150000-170000 for the enzyme was estimated in experiments performed by gel-filtration chromatography on dextran and agarose gels. Investigation of the interaction with, and hydrolysis by, rat PDase II of a number of possible phosphodiester substrates indicated that'-, the enzyme required a nucleoside 3'-phosphoryl residue for the initiation of hydrolysis which then proceeded in a 5'+3' direction. Finally, the effect of some enzyme inhibitors was investigated. PDase II activity was inhibited in the presence; of NEM, PCMB, PCMPS and iodoacetic acid. It was further found that the inactivation by iodoacetic acid could be prevented by the presence of a PDase substrate or, better still, by dTp. This is good evidence that iodoacetate alkylates an essential residue at the active center of PDase II and is the first time that such an effect has been shown for a PDase. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

by Wong Ping Shing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 97-112). / ACKNOWLEDGMENTS --- p.i / ABSTRACT --- p.ii / ABBREVIATIONS --- p.viii / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- General properties of zinc / Chapter 1.1.1 --- Biochemistry of zinc --- p.2 / Chapter 1.1.2 --- Distribution of zinc in body --- p.3 / Chapter 1.1.3 --- Roles of zinc in protein function --- p.4 / Chapter 1.2 --- Zinc and zinc-binding proteins in brain / Chapter 1.2.1 --- Distribution of zinc in brain --- p.7 / Chapter 1.2.2 --- Metabolism of zinc in brain --- p.9 / Chapter 1.2.3 --- Compartments of zinc in brain --- p.10 / Chapter 1.2.4 --- Zinc-binding proteins in brain --- p.12 / Chapter 1.3 --- Pathological conditions of brain in relation to zinc --- p.15 / Chapter 1.4 --- Aim of the project --- p.20 / Chapter 2. --- MATERIALS AND METHODS --- p.22 / Chapter 2.1 --- Detection of zinc-binding proteins / Chapter 2.1.1 --- Sodium-Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE) --- p.22 / Chapter 2.1.2 --- Electroblotting --- p.24 / Chapter 2.1.3 --- Radioactive zinc blotting --- p.25 / Chapter 2.1.4 --- Autoradiography --- p.25 / Chapter 2.2 --- Subcellular fractionation of porcine brain --- p.26 / Chapter 2.3 --- Purification and structural characterization of a 19 kDa zinc-binding protein / Chapter 2.3.1 --- Purification of a 19 kDa protein --- p.27 / Chapter 2.3.2 --- Sequencing of N-terminal blocked 19 kDa protein --- p.30 / Chapter 2.4 --- Characterization of the binding and biological properties of the 19 kDa zinc-binding protein / Chapter 2.4.1 --- Effect of divalent metal ions on zinc binding to the 19 kDa protein --- p.33 / Chapter 2.4.2 --- Effect of pH on the dissociation of radioactive zinc from the19 kDa protein --- p.34 / Chapter 2.4.3 --- Radioactive calcium blotting --- p.34 / Chapter 2.4.4 --- Interaction of radioactive zinc and radioactive calcium binding to the 19 kDa protein --- p.35 / Chapter 2.4.5 --- Calmodulin activity assay --- p.35 / Chapter 3. --- RESULTS / Chapter 3.1 --- Specificity of radioactive zinc-blot on zinc-binding protein detection --- p.38 / Chapter 3.2 --- Zinc-binding proteins in porcine brain --- p.38 / Chapter 3.3 --- Purification and identification of a cytosolic 19 kDa zinc- binding protein in porcine brain / Chapter 3.3.1 --- Zinc-dependent hydrophobic interaction chromatography --- p.44 / Chapter 3.3.2 --- N-terminal amino acid sequencing --- p.51 / Chapter 3.3.3 --- High pH native gel electrophoresis of 19 kDa protein --- p.51 / Chapter 3.4 --- The zinc and calcium binding properties of the 19 kDa protein / Chapter 3.4.1 --- Effect of pre-exposure to divalent cations on zinc binding --- p.54 / Chapter 3.4.2 --- Competition by divalent cations for zinc binding --- p.56 / Chapter 3.4.3 --- pH dependency of zinc dissociation --- p.56 / Chapter 3.4.4 --- Effect of zinc on radioactive calcium binding --- p.61 / Chapter 3.5 --- The biological activity of the 19 kDa protein / Chapter 3.5.1 --- Effect of the 19 kDa protein on the activity of calmodulin- dependent phosphodiesterase --- p.66 / Chapter 3.5.2 --- Effect of zinc on calmodulin-dependent phosphodiesterase activity --- p.69 / Chapter 3.5.4 --- "Effect of zinc on calcium-deficient, calmodulin-dependent phosphodiesterase activity" --- p.72 / Chapter 4. --- DISCUSSION / Chapter 4.1 --- Detection and Purification of zinc-binding proteins / Chapter 4.1.1 --- Strategy for the detection of zinc-binding proteins --- p.77 / Chapter 4.1.2 --- Purification of zinc-binding protein --- p.79 / Chapter 4.2 --- Amino acid sequencing of the 19 kDa protein --- p.82 / Chapter 4.3 --- Binding properties of the 19 kDa zinc-binding protein --- p.86 / Chapter 4.4 --- Effect of zinc and 19 kDa zinc-binding protein on calmodulin dependent phosphodiesterase --- p.92 / Chapter 4.5 --- Effect of zinc on the properties of calmodulin --- p.90 / Chapter 4.6 --- Significance of the ability of zinc to affect calmodulin activity --- p.94 / Chapter 5. --- CONCLUSION --- p.95 / Chapter 6. --- REFERENCES --- p.97

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 102-118).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 120-138).

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 132-145).

Made available in DSpace on 2013-08-07T18:41:21Z (GMT). No. of bitstreams: 1 000401022-Texto+Completo-0.pdf: 970049 bytes, checksum: 1fc17227f3815a94113f9cadc1efc0e4 (MD5) Previous issue date: 2008 / Phosphodiesterases (PDEs) are a super family of enzymes which degrade the intracellular second messengers cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP). As essential regulators in cyclic nucleotide signaling with diverse physiological functions, PDEs are drug targets for the treatment of various diseases including heart failure, depression, asthma, inflammation, and erectile dysfunction. Among the eleven PDE gene families, the cGMP-specific PDE5 is the principal cGMP-hydrolyzing activity in the human corpus cavernosum tissue. It is well known as the target of many drugs used in the treatment of erectile dysfunction, like sildenafil. This work aims the synthesis of the coding region, cloning, expression and purification of the catalytic domain of human PDE5 gene which encodes the phosphodiesterase 5. The synthesis of the coding region of the target polypeptide was accomplished by using 24 primers, which were ligated by overlap extension using the polymerase chain reaction. The construction was cloned into pCRBlunt® vector and sequenced to confirm its identity and the absence of mutations. The fragment was subcloned into pET23a(+) expression vector with NdeI and BamHI restriction sites. Escherichia coli Rosetta (DE3) electrocompetent cells were transformed with the recombinant plasmid and the coding region of the catalytic domain of the PDE5 was expressed in its soluble form with 0. 1mM of IPTG induction. The purification yielded 2. 39 mg. mL-1 through 3 steps of purification. The pure catalytic domain of PDE5 will allow screening for the discovery of new natural inhibitors from the brazilian biodiversity that could be used in the treatment of erectile dysfunction. / Fosfodiesterase (PDE) é uma super família de enzimas responsáveis pela degradação dos segundos mensageiros intracelulares adenosina monofosfato cíclico (AMPc) e guanosina monofosfato cíclico (GMPc). Como reguladoras essenciais na sinalização de segundos mensageiros cíclicos com diversas funções fisiológicas as PDEs são alvo de drogas para o tratamento de diversas doenças. Dentre estas estão insuficiência cardíaca, depressão, asma, inflamação e disfunção erétil. Dentre as 11 famílias de genes de PDE, a fosfodiesterase 5 (PDE5) é específica para GMPc, sendo responsável pela atividade de hidrólise que sofre o GMPc dentro dos tecidos dos corpos cavernosos penianos dos homens. A PDE5 é amplamente conhecida por ser alvo de diversas drogas utilizadas no tratamento da disfunção erétil, como por exemplo, o sildenafil (Viagra®). Este trabalho tem por objetivo a síntese da região codificante, clonagem, expressão e purificação do domínio catalítico da PDE5 humana. A síntese da região codificante do polipeptídeo alvo foi realizada através da técnica de overlap, utilizando 24 oligonucleotídeos que foram unidos através da reação em cadeia da polimerase (PCR). A construção foi clonada em vetor pCRBlunt® e sequenciada para confirmar sua identidade e a ausência de mutações. O fragmento foi subclonado em vetor de expressão pET23a(+) com sítios de restrição NdeI e BamHI, para o N terminal e C terminal, respectivamente. Células eletrocompetentes de E. coli Rosetta (DE3) foram transformadas com o plasmídeo recombinante, a região que codifica para o domínio catalítico da PDE5 foi expressa em sua forma solúvel e ativa na presença de 0,1 mM do indutor IPTG. Quando o domínio catalítico da PDE5 foi isolado, um rendimento de 2,39 mg. mL-1 foi obtido através de 3 passos de purificação.O domínio catalítico da PDE5 puro permitirá a realização de uma triagem de extratos vegetais oriundos da biodiversidade brasileira. Com o intuito de buscar novos compostos que possam se tornar possíveis inibidores de PDE5, e assim serem utilizados no tratamento da disfunção erétil.

Made available in DSpace on 2015-04-14T14:50:50Z (GMT). No. of bitstreams: 1 401022.pdf: 970049 bytes, checksum: 1fc17227f3815a94113f9cadc1efc0e4 (MD5) Previous issue date: 2008-03-19 / Fosfodiesterase (PDE) ? uma super fam?lia de enzimas respons?veis pela degrada??o dos segundos mensageiros intracelulares adenosina monofosfato c?clico (AMPc) e guanosina monofosfato c?clico (GMPc). Como reguladoras essenciais na sinaliza??o de segundos mensageiros c?clicos com diversas fun??es fisiol?gicas as PDEs s?o alvo de drogas para o tratamento de diversas doen?as. Dentre estas est?o insufici?ncia card?aca, depress?o, asma, inflama??o e disfun??o er?til. Dentre as 11 fam?lias de genes de PDE, a fosfodiesterase 5 (PDE5) ? espec?fica para GMPc, sendo respons?vel pela atividade de hidr?lise que sofre o GMPc dentro dos tecidos dos corpos cavernosos penianos dos homens. A PDE5 ? amplamente conhecida por ser alvo de diversas drogas utilizadas no tratamento da disfun??o er?til, como por exemplo, o sildenafil (Viagra?). Este trabalho tem por objetivo a s?ntese da regi?o codificante, clonagem, express?o e purifica??o do dom?nio catal?tico da PDE5 humana. A s?ntese da regi?o codificante do polipept?deo alvo foi realizada atrav?s da t?cnica de overlap, utilizando 24 oligonucleot?deos que foram unidos atrav?s da rea??o em cadeia da polimerase (PCR). A constru??o foi clonada em vetor pCRBlunt? e sequenciada para confirmar sua identidade e a aus?ncia de muta??es. O fragmento foi subclonado em vetor de express?o pET23a(+) com s?tios de restri??o NdeI e BamHI, para o N terminal e C terminal, respectivamente. C?lulas eletrocompetentes de E. coli Rosetta (DE3) foram transformadas com o plasm?deo recombinante, a regi?o que codifica para o dom?nio catal?tico da PDE5 foi expressa em sua forma sol?vel e ativa na presen?a de 0,1 mM do indutor IPTG. Quando o dom?nio catal?tico da PDE5 foi isolado, um rendimento de 2,39 mg.mL-1 foi obtido atrav?s de 3 passos de purifica??o. O dom?nio catal?tico da PDE5 puro permitir? a realiza??o de uma triagem de extratos vegetais oriundos da biodiversidade brasileira. Com o intuito de buscar novos compostos que possam se tornar poss?veis inibidores de PDE5, e assim serem utilizados no tratamento da disfun??o er?til.

Le présent mémoire a pour sujet le développement d’une méthode rapide et efficace vers la production d’allènes hautement substitués à partir de dérivés cyclopropaniques électrophiles énantioenrichis. L’avancement de méthodes synthétiques intéressantes pour la production asymétrique de ces dérivés de cyclopropane-1,1-diesters sera également présenté. Dans un premier temps, les différentes méthodes de synthèses des cyclopropanes activés seront abordées, ainsi que leur utilisation dans la préparation de molécules plus complexes. Par la suite, les techniques précédentes de préparation asymétrique des allènes seront introduites, démontrant ainsi la difficulté de leur accessibilité. Le développement d’une méthode fiable pour la synthèse de cyclopropane-1,1-diesters utilisant les ylures d’iodonium sera présenté. Finalement, l’accessibilité à plusieurs types d’allènes hautement substitués par l’utilisation de cuprates sera détaillée. Dans une seconde partie, il sera davantage question de l’accessibilité des cyclopropane-1,1-diesters énantioenrichis. Ces derniers sont d’un intérêt particulier, car ils constituent le point de départ de notre méthodologie précédente. Le développement d’une méthode pouvant être utilisée à grande échelle et à faible coût a donc été explorée. Les deux derniers chapitres présenteront donc les tentatives de générer ces cyclopropanes activés par résolution cinétique ou encore par l’hydrogénation asymétrique des cyclopropènes correspondants. / The subject of this present M.Sc. thesis is the developpement of an efficient and fast methodology toward the production of highly substituted allenes using enantioenriched cyclopropanes derivatives. The development of new synthetic methodologies in the production of these enantioenriched cyclopropan-1,1-diesters will be presented. First, the various methodologies for the preparation of activated cyclopropanes will be discussed along with their uses in the synthesis of more complex molecules. Then, the precedents in the field of asymmetric allenes synthesis will be introduced. The developpement of a viable method for the synthesis of cyclopropane-1,1-diesters using iodonium ylides will be presented. Finally, the accessibility of different highly substituted allenes by the used of cuprates will be detailed. In a second part, we will elaborate on the accessibility of the enantioenriched cyclopropane-1,1-diesters derivatives. These compounds are interesting, because they are used as starting materials in the previous methodology of allenes synthesis. This methodology has to be usable in large scale and at small cost. The last two chapters of this thesis will present the alternatives strategies for the preparation of these activated cyclopropanes by either kinetic resolution or the asymmetric hydrogenation of cyclopropenes.

No description available.

Le présent mémoire a pour sujet le développement d’une méthode rapide et efficace vers la production d’allènes hautement substitués à partir de dérivés cyclopropaniques électrophiles énantioenrichis. L’avancement de méthodes synthétiques intéressantes pour la production asymétrique de ces dérivés de cyclopropane-1,1-diesters sera également présenté. Dans un premier temps, les différentes méthodes de synthèses des cyclopropanes activés seront abordées, ainsi que leur utilisation dans la préparation de molécules plus complexes. Par la suite, les techniques précédentes de préparation asymétrique des allènes seront introduites, démontrant ainsi la difficulté de leur accessibilité. Le développement d’une méthode fiable pour la synthèse de cyclopropane-1,1-diesters utilisant les ylures d’iodonium sera présenté. Finalement, l’accessibilité à plusieurs types d’allènes hautement substitués par l’utilisation de cuprates sera détaillée. Dans une seconde partie, il sera davantage question de l’accessibilité des cyclopropane-1,1-diesters énantioenrichis. Ces derniers sont d’un intérêt particulier, car ils constituent le point de départ de notre méthodologie précédente. Le développement d’une méthode pouvant être utilisée à grande échelle et à faible coût a donc été explorée. Les deux derniers chapitres présenteront donc les tentatives de générer ces cyclopropanes activés par résolution cinétique ou encore par l’hydrogénation asymétrique des cyclopropènes correspondants. / The subject of this present M.Sc. thesis is the developpement of an efficient and fast methodology toward the production of highly substituted allenes using enantioenriched cyclopropanes derivatives. The development of new synthetic methodologies in the production of these enantioenriched cyclopropan-1,1-diesters will be presented. First, the various methodologies for the preparation of activated cyclopropanes will be discussed along with their uses in the synthesis of more complex molecules. Then, the precedents in the field of asymmetric allenes synthesis will be introduced. The developpement of a viable method for the synthesis of cyclopropane-1,1-diesters using iodonium ylides will be presented. Finally, the accessibility of different highly substituted allenes by the used of cuprates will be detailed. In a second part, we will elaborate on the accessibility of the enantioenriched cyclopropane-1,1-diesters derivatives. These compounds are interesting, because they are used as starting materials in the previous methodology of allenes synthesis. This methodology has to be usable in large scale and at small cost. The last two chapters of this thesis will present the alternatives strategies for the preparation of these activated cyclopropanes by either kinetic resolution or the asymmetric hydrogenation of cyclopropenes.