Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 120-142).

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Michael Chapman, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Sept. 15, 2005). Document formatted into pages; contains vi, 76 pages. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2005.

A number of peptide fragments including (2S)-Pro-(2S)-Ile-NHiBu (72) and (2S)-Phe-(2S)-Ile-NHiBu (73) and l-(benzyloxycarbonyl)-aminophosphinic acid methyl esters (analogues of Phe (76), Cha (77) and Leu (78)) have been synthesised and coupled to give a series of phosphonamidate methyl ester-based peptide inhibitors of HIV-1 proteinase. These compounds were tested against the proteinase enzyme in vitro using a spectrophotometric assay and displayed activities in the 1-100 muM range. Remarkably, comparison of these data with data obtained for activities against HIV-1 in cultured human lymphocytes showed an in vitro:in vivo ratio of approximately 1:1. These results are indicative of a highly efficient cell uptake mechanism and exceed the reported in vitro:in vivo ratios for HIV proteinase inhibitors by a factor of 103. It is also apparent from the results that the compounds are not rapidly degraded in human lymphocytes. The activities of these compounds, however, was rather insensitive to small structural changes, undermining our attempts to optimise them. A phosphonamidate ethyl ester (Cbz-Phe-PO(OCH2CH3)NH-(2S)-Phe-(2S)-Ile- NHiBu (94)) was prepared and this possessed an IC50 of 4.5 muM, indicating that it might be possible to incorporate larger ligands onto the ester portion of the molecule. Due to the problems associated with peptidic compounds as therapeutic agents, a number of non-peptidic targets were designed. 3,3'-Di- (benzyloxycarbonyl)-aminobenzoin (103) was synthesised in three steps from m- nitrobenzaldehyde and this displayed an IC50 of 8 muM. Molecular modelling of a second target, a bicyclic phosphorodiamidate (106), showed that this compound should adopt a skewed position within the enzyme's active site, with the OH group between the catalytic aspartates (Asp 25 and Asp 25') and the P=0 strongly hydrogen-bonded to one of the flap Ile's but relatively distant from the other. A synthesis of this molecule from tris (hydroxymethyl)amino-methane was undertaken, but problems with this led to the design of the less-substituted phosphorodiamidate (116). An alternative route from diethyl malonate was begun, although to date this has not been completed. This work is now under investigation by others in our group.

Made available in DSpace on 2016-04-28T20:16:24Z (GMT). No. of bitstreams: 1 2007- Fabiano Araujo Pires-01.pdf: 878766 bytes, checksum: 9179bfb28ddd6cee14d8d4414534b8f8 (MD5) Previous issue date: 2007-04-26 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / We performed a combination of proteinase assay, either in solution or immobilized in sodium dodecyl sulfate-polyacrylamide gel copolymerized with gelatin, to detect and quantify proteinases of Dermatobia hominis second (L2) and third (L3) instar larvae. In quantitative assays, we examined proteinase activity by hydrolysis of a panel of peptide bonds specific for the main proteinase classes. We verified that the pGlu-Phe-Leu p-nitroanilide substrate was hydrolyzed by crude extracts of L2 (3.0 ? 0.2 nmoles hour-1 mg of protein-1) and L3 (7.7 ? 0.1 nmoles hour-1 mg of protein-1) and that both activities were partially inhibited by transepoxysuccinyl- L-leucylamido-(4-guanidino)butane, 15 % and 3 % respectively. Also, we demonstrated that the Na-p-Tosyl-L-Arg methyl ester substrate was hydrolyzed by crude extracts of L2 (117 ? 24 nmoles hour-1 mg of protein-1) and L3 (111 ? 10 nmoles hour-1 mg of protein-1), suggesting a predominance of esterase activity in the crude larval preparation. Interestingly, the specific activity of serine-proteinases was totally inhibited by Phenylmethylsulphonyl fluoride in the L3 crude extract, while only 10 % of this enzyme class activity was inhibited in the L2 crude extract. Also, we have detected crude extract L2 (Km = 7,59) larvae have more affinity than L3 larvae (Km = 35,75) to Na-p-Tosyl-L-Arg methyl ester. The results of the qualitative assays with substrate gels suggested that L2 and L3 larvae express serine-proteinases with similar (13 kDa and 22 kDa) and distinct (50 kDa in L2 and 30 kDa in L3) relative molecular masses. Additionally, we have isolated an enriched esterase activity from L3 crude extract using successive chromatographies in Aprotinine-Agarose and DEAE-Sephacell columns. By this strategy we detected only one 50 kDa proteinase in this larvae crude extract. Finally, these findings contribute to the biochemical characterization of D. hominis L2 and L3 larvae. / Neste trabalho foram realizados ensaios de atividade de proteinase em solu??o e com prote?nas imobilizadas em gel de poliacrilamida contendo dodecil sulfato de s?dio copolimerizado com gelatina, para detec??o e quantifica??o das proteinases presentes nos extratos larvares de segundo (L2) e terceiro (L3) est?gios de Dermatobia hominis. Nos ensaios quantitativos, utilizou-se um painel de pept?deos sint?ticos espec?ficos para as principais classes de proteinases. Verificamos que o substrato pGlu-Phe-Leu p-nitroanilide foi hidrolisado pelo extrato total de L2 (3,0 ? 0,2 nmoles hora-1 mg de prote?na-1) e L3 (7,7 ? 0,1 nmoles hora-1 mg de prote?na-1) e que ambas atividades foram parcialmente inibidas pelo trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane, 15 % e 3 % respectivamente. Tamb?m, demonstramos que o substrato Na-p-Tosyl-L-Arg methyl ester foi hidrolisado pelos extratos totais de L2 (117 ? 24 nmoles hora-1 mg de prote?na-1) e L3 (111 ? 10 nmoles hora-1 mg de proteina-1), sugerindo uma predomin?ncia da atividade ester?sica nestes extratos. A atividade espec?fica de serino-proteinases foi totalmente inibida pelo phenylmethylsulphonyl fluoride nos extratos de L3, enquanto que somente 10 % desta atividade foi inibida nos extrados de L2. Al?m disso, n?s detectamos que o extrato total das larvas L2 (Km = 7,59) tem maior afinidade ao Na-p-Tosyl-L-Arg methyl ester do que o extrato total das larva de L3 (Km = 35,75). Os resultados do ensaio qualitativo com g?is de substrato sugerem que os extratos larvares L2 e L3 expressam serino-proteinases com similares (13 kDa e 22 kDa) e distintas (50 kDa em L2 e 30 kDa em L3) massas moleculares relativas. Adicionalmente, isolamos uma atividade ester?sica enriquecida do extrato total de L3 utilizando sucessivas cromatografias em colunas de Aprotinina-Agarose e DEAE-Sephacell. Com esta estrat?gia, detectamos somente uma banda de proteinase de 50 kDa neste extrato total. Estes resultados contribuem para a caracteriza??o das proteinases larvares de D. hominis.

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