The biological half-life of several pro-inflammatory mediators involved in the pathogenesis of rheumatoid arthritis (RA) is controlled by molecules exhibiting dipeptidyl peptidase-IV (DPP-IV)-like enzymatic activity (Dipeptidyl peptidase-IV activity and/or structure homologues- DASH). The aim of this thesis was to identify the molecular source of the DPP-IV-like enzymatic activity in the peripheral blood and synovial fluid in patients with rheumatoid arthritis as compared to control patients with osteoarthritis (OA), and to evaluate the association of DPP-IV with the disease activity. We found that the main source of the DPP-IV-like enzyme activity in the plasma and in the synovial fluid in patients with RA is the canonical DPP-IV. DPP-IV-like enzymatic activity and canonical DPP-IV were also detected on the cell surface of blood and synovial fluid mononuclear cells. Significantly lower DPP-IV-like enzymatic activity and DPP-IV expression in the synovial fluid mononuclear cells was found in RA as opposed to OA patients. In the synovial fluid of RA patients there was also a negative correlation between the concentration of the pro-inflammatory DPP-IV substrate SDF (stromal cell-derived factor-1 and the proportion of the DPP-IV+ T cells. The blood plasma DPP-IV-like enzymatic activity and...

Signal peptide peptidase (SPP) and SPP-like (SPPL) aspartyl intramembrane proteases are known to contribute to sequential processing of type II-oriented membrane proteins referred to as regulated intramembrane proteolysis. The ER-resident family members SPP and SPPL2c were shown to also cleave tail-anchored proteins, including selected SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins facilitating membrane fusion events. Here, we analysed whether the related SPPL2a and SPPL2b proteases, which localise to the endocytic or late secretory pathway, are also able to process SNARE proteins. Therefore, we screened 18 SNARE proteins for cleavage by SPPL2a and SPPL2b based on cellular co-expression assays, of which the proteins VAMP1, VAMP2, VAMP3 and VAMP4 were processed by SPPL2a/b demonstrating the capability of these two proteases to proteolyse tail-anchored proteins. Cleavage of the four SNARE proteins was scrutinised at the endogenous level upon SPPL2a/b inhibition in different cell lines as well as by analysing VAMP1-4 levels in tissues and primary cells of SPPL2a/b double-deficient (dKO) mice. Loss of SPPL2a/b activity resulted in an accumulation of VAMP1-4 in a cell type- and tissue-dependent manner, identifying these proteins as SPPL2a/b substrates validated in vivo. Therefore, we propose that SPPL2a/b control cellular levels of VAMP1-4 by initiating the degradation of these proteins, which might impact cellular trafficking.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The phytochemical study of the crude extract hexane, methanol and fractions (acid ether, basic ether and basic acetate) from the stem bark of E. crista-galli (Fabaceae) resulted in the isolation of four compounds: The phytosterol stigmasterol (70), the triterpene lupeol (71) and the alkaloids erysotrine (1) and epierythratidine (50), usual in the genus Erythrina. The structures of the isolated metabolites were elucidated by 1H and 13C NMR uni and bidimensional, and compared with standard sample and data available in the literature. The extracts, fractions and isolated compounds were tested for their antimicrobial and antitumor front cancer cells HT29 (colorectal) activities, as well as regarding the capacity of inhibition of enzymes prolyl oligopeptidase, dipeptidil peptidase-VI and acetylcholinesterase. The crude methanolic extract, all fractions and individual compounds showed high antimicrobial activity mainly against Gram-positive and Gram-negative bacteria. The results were satisfactory in POP inhibition assays, when the crude methanolic extract and its fractions, mainly acid ether fraction, showed great inhibitor potential against this enzyme. For DPP-IV only the crude hexane extract was active. The in vitro antitumoral activity of the crude methanolic extract, basic fractions and the isolate alkaloids was investigated at different concentrations against the human colon cancer cell line HT-29 (PicoGreen dsDNA assay). The results suggest that the anti-proliferative effect of E. crista-galli extract on HT-29 cancer cells may be attributed, at least in part, to the presence of the erythrinian alkaloids 1 and 50. / O estudo fitoquímico do extrato bruto hexânico, metanólico e frações (éter ácida, éter básica e acetato básica) das cascas do caule de E. crista-galli (Fabaceae) resultou no isolamento de quatro compostos: o fitoesterol estigmasterol (70) e o triterpeno lupeol (71) além dos alcaloides erisotrina (1) e epieritratidina (50) usuais do gênero Erythrina. As estruturas dos metabólitos isolados foram elucidadas através de RMN 1H e 13C, uni e bidimensionais, além de comparação com amostra padrão quando existente e dados disponíveis na literatura. Os extratos, as frações e os compostos isolados foram testados quanto à sua atividade antimicrobiana, antitumoral frente a células cancerígenas HT29 (colorretal) e de inibição das enzimas POP, DPP-IV e AChE. Dentre as amostras testadas, o extrato bruto metanólico (EBM), suas frações (FEA, FEB e FAB) e compostos isolados apresentaram grande potencial antimicrobiano principalmente frente as bactérias Gram-positivas e Gram-negativas. Os resultados obtidos nos ensaios enzimáticos foram satisfatórios para a enzima POP, onde o EBM e suas frações, principalmente a fração éterea ácida (FEA), demonstraram grande potencial inibidor desta enzima. Para a DPP-IV apenas o extrato bruto hexânico (EBH) mostrou-se ativo. O efeito antitumoral da planta em questão também foi investigado e os resultados obtidos indicam que o EBM, a combinação das frações FEB e FAB e o alcaloide epieritratidina (50) possuem um grande efeito antiproliferativo frente às células do colorretal (HT29) após 72 horas de exposição.

Orientadora: Profa. Dra. Káthia Maria Honório / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia/Química, Santo André, 2018. / Um dos alvos biologicos relacionado ao controle da glicemia e a enzima dipeptidil peptidase-IV (DPP-IV); ela esta associada com a estimulacao do pancreas na producao de insulina, sendo, portanto, um alvo de interesse da pesquisa e da industria farmaceutica para o tratamento do diabetes tipo 2. O diabetes e uma doenca cronica que se caracteriza por um aumento da glicemia causando uma serie de complicacoes fisiologicas com destaque para as doencas cardiacas como a aterosclerose; estima-se que 425 milhoes de pessoas sejam portadoras da doenca. Estudos indicam que inibidores da DPP-IV tambem podem apresentar acao sobre a FAP¿¿, uma enzima que esta relacionada com reparacao de tecidos e crescimento de tumores. Este trabalho consiste em utilizar metodos de modelagem molecular, como a construcao e analise de modelos de HQSAR (Hologram Quantitative Structure-Activity) e de CoMFA (analise comparativa de campos de interacao molecular); acoplamento molecular (docking), analise de propriedades eletronicas e deteccao e caracterizacao de sitios de ligacao da enzima FAP¿¿, com intuito de compreender as principais caracteristicas de ambas as enzimas, assim como a interacao das mesmas com uma serie de compostos bioativos. Os modelos CoMFA construidos apresentaram significativos valores de validacao interna (0,768) e externa (0,986); o alinhamento obtido utilizando a tecnica de acoplamento molecular e complementada com o uso da tecnica BINANA delineou as principais interacoes das enzimas com o conjunto de ligantes; identificou-se tres sitios de ligacao da enzima FAP¿¿ utilizando os servidores FTSite e FTMap. Desta forma, com informacoes sobre ambos os alvos e as interacoes estabelecidas com os ligantes, sera possivel propor com maior seguranca modificacoes moleculares para tais compostos candidatos a farmacos mais seguros para o tratamento do diabetes tipo 2. / One of the biological targets related to glycemic control is the dipeptidyl peptidase IV (DPP-IV) enzyme; it is associated with stimulation of the pancreas in insulin production and it is a target of interest for the researches related to the treatment of type 2 diabetes. Diabetes is a chronic disease characterized by an increase in blood glucose causing a series of physiological complications such as atherosclerosis, it is estimated that 425 million people have this disease. Studies have indicated that DPP-IV inhibitors may also have action on FAPá, an enzyme that is related to tissue repair and tumor growth. This work consists of using molecular modeling methods, such as the construction and analysis of HQSAR (Hologram Quantitative Structure-Activity) and CoMFA (comparative analysis of molecular interaction fields) models; molecular docking, analysis of electronic properties, detection and characterization of FAPá enzyme binding sites, and pharmacokinetic and pharmacodynamic properties studies; in order to understand the main characteristics of both enzymes, as well as their interaction with a series of bioactive compounds. The CoMFA models presented significant values of internal validation (0,768) and external (0,986) and the alignment obtained using the molecular docking technique outlined the main interactions of the enzymes with the set of ligands. With information on both targets and the interactions established with the ligands, it will be possible to more safely propose molecular modifications for such safer drug candidates for the treatment of type 2 diabetes.

PDI ("potato cathepsin D inhibitor ") and NID ("novel inhibitor of cathepsin D ") from potato (Solanum tuberosum) belong to the protein family of Kunitz inhibitors (I3 family, Merops database). These 20 kDa isoinhibitors with the typical β-trefoil architecture inhibit aspartic and serine peptidases. In this thesis, the constructs for recombinant expression of PDI and NID in the yeast Pichia pastoris system were prepared and high-producing colonies were selected. Both proteins were identified in the cultivation media by mass spectrometry and N-terminal sequencing. A purification protocol for PDI with three chromatographic steps was designed. Analogous functional properties were demonstrated for the purified recombinant PDI and the native PDI isolated from a natural source. Analysis of the inhibitory specificity showed that PDI is a potent inhibitor of selected aspartic peptidases from the A1 family and serine peptidases from the S1 family, including a relevant enzyme of insect origin. This finding supports the hypothesis that Kunitz inhibitors are involved in plant defense against herbivorous insects. The inhibitors prepared within the project will be used for analysis of the reactive centers against target peptidases by protein crystallography. (In Czech) Key words: proteolytic enzymes, activity...

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