As the first structural example of this class of proteins, crystals of Pro-RIP and MOD were grown and diffracted to 2.4 and 2.5 A respectively. The structures of the two proteins are solved and found to be highly similar, with main chain RMSD of 0.519. Each protein has two domains. The N-terminal domain consists of five alpha-helices and five-stranded mixed beta-sheet. The conserved active site residues Y94, Y130, E207, R210 and W241, similar to those of other RIPs, are located at the cleft between the N-terminal and C-terminal domains. In Pro-RIP, the 25-amino acid internal inactivation region is found on the surface of the N-terminal domain and consists of a flexible loop followed by a long alpha-helix. Like bacterial ribosome-inactivating proteins, maize ribosome-inactivating protein does not have a back-up glutamate in the active site, which helps the protein to retain some activity if the catalytic glutamate is mutated. The structure of maize RIP reveals that the active site is too small to accommodate two glutamate residues and suggests that maize ribosome-inactivating protein may represent an intermediate product in the evolution of ribosome-inactivating proteins. / Pull-down assay indicated that the internal inactivation region diminished the interaction of Pro-RIP with purified ribosomes and ribosomal proteins P0, P1 and P2. Surface plasmon resonance assays showed that Pro-RIP has a slower association rate and faster dissociation rate on intact ribosomes when compared to MOD, resulting 80-fold decrease in binding affinity. These evidences strongly suggested that the reduced ribosome-inactivating activity and cytotoxicity of Pro-RIP is the result of its diminished interaction with the ribosomes. The ribosome binding site of MOD is found to be different from TCS and saporin, which are located between the anti-parallel beta-sheet in the C-terminal domain. In MOD, the positive-charged residues K158, K159, K160 and K161 that were found to be important for ribosome binding are located in the N-terminal domain, underneath the internal inactivation region. / Ribosome-inactivating proteins (RIPs) are rRNA N-glycosidases, which hydrolyze the N-glycosidic bond of A-4324 in 28S rRNA of eukaryotic ribosomes. Based on the number of subunits, RIPs are grouped into three classes. Type I RIPs (e.g. trichosanthin and saporin) are monomeric polypeptide with molecular weights of 25-32 kDa. Type II RIPs (e.g. ricin and cinnamomin) are heterodimeric proteins whose subunits are linked by a disulphide bridge, with molecular weights of 60-65 kDa. Chain A of type II RIPs is the catalytic subunit, while chain B is the lectin subunit, which facilitates the cellular entry of the protein by interacting with carbohydrates on the cell surface. Maize ribosome-inactivating protein is classified as a type III RIP, or an atypical RNA N-glycosidase. It is synthesized and stored in the kernel as a 34 kDa inactive precursor (Pro-RIP). During germination, the precursor undergoes proteolysis to generate a two-chain active RIP (MOD). Previous study has found that the 25-amino acid residues at the acidic internal inactivation region, which are removed during activation of Pro-RIP, is the major control element to suppress its in vitro protein synthesis inhibition activity. / Since the internal inactivation region of Pro-RIP controls the ribosome-inactivating activity and cytotoxicity, it provides an opportunity to engineer an on/off switch forits activity by HIV-1 protease through engineering HIV-1 protease recognition sites into the internal inactivation region of Pro-RIP. A variant that contains two HIV-1 protease recognition sites incorporated to the 25-amino acid internal inactivation region was found to be activated by HIV-1 protease in vitro. This variant entered cells more efficiently than Pro-RIP and was as cytotoxic as MOD. This switch may be applied to other RIPs such as ricin A chain and other protease recognition sequences may be used for increasing the specificity of an RIP toward viral infected cells. / The internal inactivation region of Pro-RIP greatly decreases its cytotoxicity, but not cellular uptake through alpha-2 macroglobulin receptor. On the contrary, the acidic residues within the region hinder fluid-phase endocytosis. Moreover, it is found that the internal inactivation region does not affect sub-cellular localization of the protein - MOD and Pro-RIP locate in the same cellular compartment (nucleus in JAR or cytoplasm in J774A.1 and C8166). / Mak, Nga Sze Amanda. / "July 2007." / Adviser: Shaw Pang Chui. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 216-236). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Anbu is a bacterial protein with significant homology to the sub-units of the 20S proteasome and is predicted to be a novel bacterial proteasome. The goal of this project was to determine if the recombinant Anbu protein from Pseudomonas aeruginosa is a proteasome. Anbu from P. aeruginosa was successfully cloned, expressed and purified. In order to determine the catalytic activity of Anbu, the purified protein was tested with a variety of substrates and conditions. The targets analyzed included fluorescently-labeled substrates, denatured proteins, diubiquitin, and a peptide library in the hopes of obtaining a useful model substrate. Experiments were also conducted to determine what role Anbu has in the cell. Western analysis was performed on the cell lysate of wild type P. aeruginosa and insertional mutants to detect Anbu expression. The level of biofilm formation was compared between the wild type and mutants. Cultures were grown under stress conditions including the oxidative stress of diamide and the nitrosative stress of S-nitrosoglutathione. Growth rates were monitored in an attempt to detect a phenotypic difference between the wild type and the mutants lacking Anbu, HslV, and the other proteins of interest. While a substrate for Anbu has yet to be found, this protein was found to assemble into a larger structure and P. aeruginosa lacking Anbu was sensitive to the oxidative stress of diamide and the nitrosative stress of S-nitrosoglutathione.

HIV protease inhibitors (PI) are core components of Highly Active Antiretroviral Therapy (HAART). HIV PIs are extremely effective at suppressing viral load, but have been linked to lipodystrophy and dyslipidemia, which are major risk factors for cardiovascular disease. Recent studies indicate that activation of endoplasmic reticulum (ER) stress is an important cellular mechanism underlying HIV PI-induced dysregulation of lipid metabolism. However, the exact role of ER stress in HIV PI-associated lipodystrophy and dyslipidemia remains to be identified. Hepatocytes and adipocytes are important players in regulating lipid metabolism and the inflammatory state. Dysfunction of these two cell types is closely linked to various metabolic diseases. In this dissertation research, we aimed to define the role of activation of ER stress in HIV PI-induced dysregulation of lipid metabolism in adipocytes and hepatocytes and further identifty the potential molecular mechanisms. Both cultured and primary mouse adipocytes and hepatocytes were used to examine the effect of individual HIV PIs on ER stress activation and lipid metabolism. The results indicated that HIV PIs differentially activate ER stress through depletion of ER calcium stores, activating the unfolded protein response (UPR). UPR activation further lead to an alteration of cellular differentiation through downstream transcription factor CHOP. At the same time, HIV PIs also altered adipogenesis via differential regulation of the adipogenic transcription factor PPARγ. HIV PI-induced ER stress was closely linked to dysregulation of autophagy activation through CHOP, and upstream ATF-4, signaling pathways. In hepatocytes, the integrase inhibitor raltegravir abrogated HIV PI-induced lipid accumulation by inhibiting ER stress activation and dysregulation of autophagy pathway. Our studies suggest that both ER stress and autophagy are involved in HIV PI-induced dysregulation of lipid metabolism in adipocytes and hepatocytes. The key components of ER stress and autophagy signaling pathways are potential therapeutic targets for HIV PI-induced metabolic side effects in HIV HAART-treated patients.

HIV protease inhibitors are an important component of Highly Active Antiretroviral Therapy used to treat HIV infected pregnant women. They have a low placental transfer and are highly plasma protein bound. The purpose of this thesis was to characterize the factors limiting placental passage and fetal exposure to lopinavir. These factors include lopinavir plasma protein binding and uptake, cellular binding, and efflux of lopinavir in the placental trophoblast cells. First, we determined the unbound fraction of lopinavir in cord blood and characterized the binding of lopinavir to α1-acid glycoprotein (AAG) and human serum albumin (HSA), and displacement by ritonavir. Serum was obtained from cord blood from placentae obtained after cesarean section of healthy non-HIV infected women (n=4). The unbound fraction of lopinavir in serum obtained from this cord blood was 0.02 ± 0.01. The unbound fraction of lopinavir in separately obtained maternal serum samples (n=4) was 0.009 ± 0.001, which was not significantly different from that observed with cord serum samples. Varying concentrations of lopinavir, AAG, and HSA in buffer solutions were then used to characterize the lopinavir binding. The data were fit to obtain the number of binding sites (N) and equilibrium dissociation constant (KD). Binding of lopinavir to AAG (7-23 µM) was saturable with KD of 5.0 ± 1.1 µM and N of 1.2 ± 0.2. At low HSA concentrations (15-152 µM), lopinavir binding KD was 24.3 ± 8.7 µM and N was 1.1 ± 0.4; however at 758 µM, lopinavir binding was essentially unsaturable. Additionally, lopinavir binding to AAG and HSA was not sensitive to ritonavir within the range of therapeutic concentrations. Next, we examined lopinavir uptake, binding and efflux using the BeWo human trophoblast cell culture model. BeWo cells were treated with 3H-lopinavir in the absence or presence of inhibitors of ATP- Binding Cassette transporters. The radioactivity was then measured in the buffer and the cells after incubating for different time intervals and at two temperatures. Verapamil (100µM) stimulated apparent efflux of 3H lopinavir by two fold, possibly due to ABCC2. In addition, this efflux process was 75% inhibited by reduced temperature (4°C). Ritonavir (10 µM) also stimulated 3H-lopinavir efflux, whereas GF120918 (1 µM) had no effect. Reduced temperature (4°C), verapamil (100 µM) or ritonavir (10 µM) individually did not significantly affect the binding of 3H-lopinavir to cell homogenates. However, slight but significant binding displacement by verapamil at 4°C was observed. 3H lopinavir uptake was not sensitive to verapamil, bromosulfophthalein, taurocholate or to reduced temperature suggesting uptake involves diffusion rather than Organic Anion Transporting Polypeptide transporters. The results suggested that interplay between cellular binding and ABC efflux transporters, in addition to simple diffusion, determines the extent of 3H-lopinavir distribution into BeWo cells.

A resistência que apresentam as serpentes peçonhentas às suas próprias peçonhas, assim como a resistência observada em alguns animais está bem documentada, e é atribuída a fatores solúveis presentes no seu plasma, soro ou músculo. No caso das serpentes peçonhentas estes fatores as amparam de sofrer danos decorrentes da própria peçonha. No presente trabalho foi isolado do soro da serpente Bothrops alternatus um inibidor de metaloproteases, denominado BaltMPI, mediante cromatografia em DEAE Sepharose(TM), Superdex(TM) 200, MonoQ(TM) 5/50 GL e cromatografia de fase reversa em C18, com uma recuperação proteica de 0,3%. A massa molecular determinada para o BaltMPI por SDS - PAGE foi de 60,5 kDa, e por espectrometria de massas MALDI/TOF de 42,4 kDa. Seu ponto isoelétrico, determinado por focalização isoelétrica, é 5,27. Portanto, o BaltMPI, é um SVMPIs com caráter ácido, pertencente aos SVMPIs de baixa massa molecular. Os primeiros 60 aminoácidos da região N-terminal do BaltMPI foram determinados mediante degradação de Edman, e apresentou alto grau de homologia com a sequência para a mesma região de outros SVMPIs isolados a partir do soro de serpentes peçonhentas. Outros segmentos da sequência também foram determinados após clivagem com tripsina e posterior análise por espectrometria de massas. Posteriormente realizou-se o alinhamento da sequência parcial determinada para o BaltMPI, com a sequência do BJ46a, um SVMPI proveniente da Bothrops jararaca, encontrando alta homologia entre elas. Tanto o soro da serpente, quanto o inibidor, BaltMPI, inibiram a atividade hemorrágica da Batroxase, uma SVMP da classe P-I, e a da BjussuMP-I, uma SVMP da classe P-III. Já, em relação à DHM da Batroxase, foi determinado que o BaltMPI tem uma DIHM de 5ug, e uma CE50% de 0,857ug. O BaltMPI também apresentou um efeito inibitório sobre a ação proteolítica da Batroxase, sobre os substratos: fibrinogênio, fibrina e azocaseína. Sobre a atividade fibrinogenolítica da serinoprotease BjSP, o BaltMPI não apresentou um efeito inibitório, corroborando assim com a especificidade descrita para inibir as SVMPs que possuem os SVMPIs. O BaltMPI inibiu a ação hemorrágica e proteolítica da Batroxase, ao formar um complexo mediante ligações não covalentes com esta SVMP. O inibidor BaltMPI, ao igualmente aos demais SVMPIs descritos, é estável em uma ampla faixa de pH (1 - 9), e a temperaturas elevadas, sendo que em temperaturas acima de 60°C foi observada uma diminuição na sua capacidade de inibir a atividade hemorrágica da Batroxase. A inibição da atividade hemorrágica da Batroxase, quando avaliado o potencial do BaltMPI como complemento à soroterapia, foi menor à inibição observada ao realizar os testes com incubação prévia entre o inibidor e a metaloprotease. No entanto, os resultados obtidos são promissores, reforçando o grande potencial que os SVMPIs possuem, tanto como ferramentas moleculares, como opção para o tratamento dos acidentes ofídicos, em especial o acidente botrópico, no qual as SVMPs tem papel fundamental na fisiopatologia observada, e que conduz à alta morbidade associada com este tipo de acidente. / Resistance exhibited by snakes to their own venom, as well as resistance observed in some animals has been well recorded, and has also attributed to soluble factors present in the plasma, serum or muscle. In the case of poisonous snakes, these factors protect them from damages caused by their own venom. An inhibitor, named as BaltMPI, was isolated from the snake´s serum of Bothrops alternates. This inhibitor was isolated through several chromatographic steps including DEAE Sepharose(TM), Superdex(TM) 200, MonoQ(TM) 5/50 GL and C-18 reverse phase, with a protein yield of 0.3%. Molecular mass of 60.5 kDa for BaltMPI was determined by SDS - PAGE and 42.4 kDa by MALDI/TOF mass spectrometry. Its isoelectric point, determined by isoelectric focalization, was 5.27. According to the obtained data, it was established that BaltMPI is an SVMPIs of acid character, belonging to low molecular mass SVMPIs. The first 60 aminoacids from the N-terminal region were determined by Edman degradation. This parcial sequence showed high homology to the corresponding sequence of other SVMPIs isolated from poisonous snake´s serum. Other segments from the sequence were also determined after cleavage with tripsine and MS analyses. Consequently, alignment of the partial sequence of BaltMPI with the sequence of BJ46a, a SVMPI from Bothrops jararaca, was made finding high homology. Both, snake´s serum and BaltMPI, inhibited the hemorragic activity of Batroxase, a class P-I SVMP, and of BjussuMP-I, a class P-III SVMP. When compared to the Batroxase DHM, it was determined a DIHM of 5?g and a CE50% of 0.857?g. BaltMPI also exhibited an inhibitory activity against the proteolitic effect of Batroxase on fibrinogen, fibrin and azocasein as substrates. On the fibrinogenolitic activity of serineprotease BjSP, BaltMPI did not showed inhibitory effect, demonstrating its specificity for inhibiting SVMPs that SVMPIs possess. BaltMPI inhibits the hemorragic and proteolitic action of Batroxase by forming a complex through non covalent linkages with that SVMP. BaltMPI, as well as other reported SVMPIs, is stable in a very high range of pH (1-9), and at high temperatures, although above 60°C a decrease in its inhibition capacity to the hemorrhagic activity of Batroxase. Inhibition of the hemorrhagic activity of Batroxase, when BaltMPI potencial as serum-therapy complement was evaluated, was less than the inhibition observed when tests by previously incubating inhibitor and metalloprotease were made. However, the results obtained are encouraging, highlighting the potential that these kind of proteins, SVMPIs, have as molecular tools, optional treatments for ophidic accidents, specially bothropic accident, in which SVMPs have a fundamental role in the observed physiopathology, leading to a high associated morbidity to this kind of accidents.

Sementes das plantas pertencentes à família Leguminosae são excelentes fontes de inibidores de proteases. O gênero Acacia é um dos membros mais importantes deste grupo. Neste trabalho, foram descritos novos inibidores de proteases das sementes de Acacia plumosa Lowe. A partir do extrato salino das sementes maduras, os inibidores foram purificados por cromatografia de exclusão molecular em coluna Superdex-75 (equilibrada e eluída com PBS) e cromatografia de troca iônica em coluna Mono-S, equilibrada e eluída com o tampão Acetato de Sódio 50 mM (pH 5.0) num gradiente linear de \'NA\'\'CL\' 0-0.5 M. Quatro frações (eluídas por volta de 0.1 8, 0.22, 0.33 e 0.37 M de \'NA\'\'CL\') apresentaram atividade anticoagulante e ação inibitória sobre serinoproteases, estas frações foram denominadas ApTIA, ApTIB, ApTIC e ApTID, respectivamente. Em condições nativas, a espectrometria de massas mostrou as massas moleculares de três deles (A, B e C): 19.709; 19.869 e 20.378 Dáltons, enquanto que em SDS-PAGE na presença de \'beta\'-mercaptoethanol, foram observadas duas cadeias para cada um dos inibidores. A análise dos primeiros 10 resíduos de aminoácidos da região N-Terminal das duas cadeias das formas A, B, C revelou identidade com inibidores do tipo Kunitz, e também mostrou dois resíduos diferentes na ApTIC, em relação as formas A e B. Estes dados levam a interpretação de que estes inibidores são diferentes isoformas encontradas nesta semente. O espectro de dicroísmo circular foram compatíveis com proteínas que majoritariamente apresentam elementos- β e não-ordenados em sua estrutura, apresentando máximos positivos por volta de 230 nm e mínimos em 202 nm. Os três isoinibidores foram muito estáveis em pHs ácidos e alcalinos, e suas estruturas foram afetadas somente acima de 75oC. As constantes de associação (KA) e de dissociação(KD) determinadas por SPR (num sistema BIACORE) com enzimas proteolíticas indicaram que a afinidade destes inibidores por tripsina foi até 20 vezes maior que para quimotripsina (tripsina: KA2.57x109 M-1 e quimotripsina: KA 1.34x108M-1), e o complexo tripsina-inibidor mostrou maior estabilidade (tripsina: KD por volta de 0,5 nM e quimotripsina: 6 nM). Estes inibidores também apresentaram ação inibitória sobre o crescimento dos fungos Aspergillus niger, Thielaviopsis paradoxa, Colletotrichum sp P10 e Fusarium moniliforme, mostrando que provavelmente a inibição de suas serinoproteases possa ser um mecanismo de controle das suas proliferações. / Seeds of plants belonging to Leguminosae family are rich sources of protease inhibitors. The Acacia genus is one of the most important members of this group. In this work, novel protease inhibitors from Acacia plumose Lowe seeds have been described. From the saline extract of mature seeds, the inhibitors were purified by size exclusion chromatography on Superdex-75 column (equilibrated and eluted with PBS) and ionic exchange chromatography on Mono-S column, equilibrated and eluted with Sodium Acetate 50 mM (pH 5.0) in a linear gradient of NaCl 0-0.5M. Four fractions (eluted around 0.18, 0.22, 0.33 and 0.37 M of NaCl) presented anticoagulant activity and inhibitory action on serineprotease, these fractions were denoted ApTIA, ApTIB, ApTIC and ApTID, respectively. In native conditions, mass spectrometry showed the molecular weights of three of them (A, B and C): 19,709; 19,869 and 20,378 Daltons, while in SDS-PAGE in ?-mercaptoethanol presence, two chains for each inhibitor were observed. The N-terminal analysis of the first 10 amino acid residues of both chains of the isoforms A, B, and C revealed identity with Kunitz protease inhibitors and also showed two different residues in ApTIC, comparing with A and B isoforms. These data indicate that the inhibitors are different isoforms present in this seeds. The circular dichroism spectra were compatible with proteins that majority present unordered and beta-elements in these structures, presenting positive maxima around 230 nm and minima about 202 nm. The three isonhibitors were very stable at acids and alkalines pH, and their structures are only affected over 75ºC. The association (KA) and dissociation constants (KD) determined by SPR (BIACORE system) with proteolytic enzymes indicated that the affinity of these inhibitors for trypsin was up to 20 times bigger than for chymotrypsin (trypsin: KA 2.57x109 M-1 and chymotrypsin: KA 1.37x108 M-1), and the complex inhibitor-trypsin showed higher stability (trypsin: KD around 0,5 nM and chymotrypsin: 6 nM). These inhibitors also presented inhibitory action on the fungi growth of Aspergillus niger, Thielaviopsis paradoxa, Colletotrichum sp P10 e Fusarium moniliforme showing that probably the inhibition of their serineproteases can be a mechanism of control of their proliferation.

Cada subtipo de HIV-1 tem um padrão mutacional próprio. Dados sobre mutações de resistência aos antiretrovirais foram obtidos com o subtipo B, primeiro em prevalência no Brasil. O segundo em algumas regiões é o subtipo F. Foram analisados padrões mutacionais em seqüências brasileiras de protease do subtipo F e levantou as seqüências deste subtipo disponíveis na base de dados de Stanford. A análise de dois grupos de seqüências (pacientes não tratados e tratados com inibidores de protease) mostrou 19 mutações associadas ao tratamento comuns ao subtipo B e 17 duplas de mutações associadas ao tratamento que diferem das descritas para o subtipo B, indicando a necessidade de estudos sobre rotas mutacionais no subtipo F. / Each HIV-1 subtype has a specific mutation pattern. Data on HIV-1 antiretroviral resistance mutations were obtained with subtype B, the first in prevalence in Brazil. The second in some regions is subtype F. Mutation patterns of Brazilian subtype F protease sequences were analyzed and performed a research of the sequences of Stanford Database. The analysis of two groups of sequences (untreated and treated patients with protease inhibitors) showed 19 treatment associated mutations also common in subtype B and 17 combinations of statistically treatment associated mutations that were quite different to those described for subtype B, indicating the need of studies to evaluate specific mutation pathways of subtype F.

As cianobactérias são micro-organismos reconhecidos por seu potencial em produzir cianotoxinas que afetam não só o ecossistema e a outros organismos dos ambientes aquáticos, mas também aos seres humanos, agindo em diversos órgãos e tecidos. Cerca de 600 metabólitos secundários produzidos por cianobactérias já foram descritos na literatura, sendo que muitos deles possuem potencial biológico. Os peptídeos de baixo peso molecular, produzidos por cianobactérias chamados cianopeptídeos, dos quais se podem citar as anabaenopeptinas, aeruginosinas, microviridinas, cianopeptolinas e microgininas, são compostos provindos do metabolismo secundário de cianobactérias e são descritos como inibidores de proteases e fosfatases em alguns sistemas biológicos. Sendo assim, o objetivo do estudo foi identificar a ocorrência de cianopeptídeos em cianobactérias brasileiras e testar seu efeito de inibição da atividade sobre enzimas proteases. Os objetos de estudo foram: uma linhagem da espécie Sphaerospermopsis torques-reginae, duas de Cylindrospermopsis raciborskii, duas de Microcystis sp, uma de Oscillatoria e uma de Pseudanabena sp. A partir dos resultados obtidos pode-se afirmar que do total de linhagens analisadas, ao menos 4 destas parecem produzir os cianopeptídeos de interesse, quando avaliados por cromatografia líquida de alta eficiência com detector de arranjo de diodos (HPLC-DAD). Em seguida, culturas de duas linhagens de C. raciborskii (uma produtora e outra não produtora de saxitoxina) foram amostradas a cada 3 dias, para a avaliação do crescimento celular, produção de cianopeptídeos e de saxitoxina e suas variantes. Não foi possível confirmar a produção de cianopeptídeos nas duas linhagens desta espécie. Por outro lado, foi evidenciado um aumento da produção de saxitoxinas quando cultivada num meio sem nitrogênio em comparação com a condição controle. Quando analisada a linhagem de Microcystis sp. (LTPNA 08), produtora de microcistinas, foi possível confirmar por cromatografia líquida acoplada a espectrometria de massas (LC-MS) a produção de dois cianopeptídeos, sendo estes, duas microgininas. Desta forma, desenvolveu-se um método cromatográfico para a separação desses compostos e purificação por cromatografia líquida semi-preparativa, onde foi possível a obtenção de frações enriquecidas de microgininas e microcistinas-RR e LR, com cerca de 70%, 86% e 97% de pureza. Por fim, realizaram-se ensaios avaliando a atividade da enzima conversora de angiotensina (ECA) e aminopeptidase M (AMP M) com as frações isoladas de microgininas e microcistina-LR. A atividade da ECA foi ± 50% inibida pelas frações testadas de cianopeptídeos, microcistina-LR isolada e microcistins-lR comercial. A atividade da AMP M foi 100% e 24,5% inibida quando incubada com 20 µM da fração de microgininas e microcistina-LR, respectivamente. Desta forma, as microgininas isoladas de cianobactérias brasileiras, mostraram-se como importantes inibidores da ECA e AMP M, podendo, no futuro, serem utilizadas como compostos para o tratamento de patologias cardiovasculares e renais. / Cyanobacteria are micro-organisms recognized for their potential to produce cyanotoxins that affect not only the ecosystem and other organisms of aquatic environments, but also humans, acting in various organs and tissues. Around 600 secondary metabolites produced by cyanobacteria have been described in the literature; many of them have biological potential. Low molecular weight peptides produced by cyanobacteria are called cyanopeptides, among them we can cite the anabaenopeptins, aeruginosins, microviridins, cyanopeptolins and microginins, these compounds are derived from secondary metabolisms of cyanobacteria and apparently cause inhibition of proteases and phosphatases in some biological systems. Therefore, this study targeted the identification of the occurrence of cyanopeptides in Brazilian cyanobacterias and testing its effect on the inhibition of proteases activity. The targets of study were: a strain of species Sphaerospermopsis torques-reginae, two strains of Cylindrospermopsis raciborskii, two strains of Microcystis sp. and, one strain of Pseudanabena and Oscillatoria sp. From the results obtained in this study it can be stated that at least four of the total of strains analyzed appear to produce cyanopeptides of interest, when analyzed by high-performance liquid chromatography whit phodo diodo array detector (HPLC-PDA). The cultures of two strains of C. raciborskii (a producer of saxitoxin and a non-producer) were sampled every 3 days for assessment of cell growth, production of cyanopeptides and saxitoxins. It was not possible to confirm the production of cyanopeptides in strains of this species. Nevertheless, an increase in production of saxitoxins was shown when cultivated in an environment without nitrogen, as compared to the control condition. When the strain of Microcystis sp. (LTPNA 08), a producer of microcystins, was analyzed, the production of two cyanopeptides was confirmed by using liquid chromatography-mass spectrometry (LC-MS). After confirmation, a method using HPLC-PDA was used to do the separation and purification of these compounds by semi-preparative chromatography, in which it was possible to obtain an enriched fraction of microginins, microcystin-RR and microcystin-LR with approximately 70%, 86% and 97% purity, respectively. Lastly, inhibition experiments were run with angiotensin-converting enzyme (ACE) and aminopeptidase M (AMP M) with the isolated fractions. The microginins fractions, MC-LR commercial and MC-LR isolated, showed an inhibition of ± 50% of the angiotensin-converting enzyme. The activity of AMP M was 100% and 24.5% inhibited when incubated with microginins and microcystin-LR fractions in a concentration of 20 µM, respectively. Thus, isolated microginins from Brazilian cyanobacteria have exhibited properties as potential therapeutic agents in development of inhibitors of ACE and AMP M, which can be a benefit of using these molecules in the treatment of cardiovascular and renal pathologies.

Introduction. The outermost layer of the epidermis, the stratum corneum (SC), plays a fundamental role in our defense against microorganisms, chemicals, and dehydration. The SC is composed of tightly packed keratinized skin cells, corneocytes. For a functioning skin it is essential that corneocytes are constantly shed (desquamated). Kallikrein-related peptidase (KLK) 5 and KLK7 may be important in the desquamation process through degradation of desmosomal proteins. Severe hereditary diseases, where inhibition of KLK5 and/or KLK7 is missing, points to the importance of regulation of protease activity. KLKs may be regulated in various ways: tissue expression, activation of proforms, specific inhibitors, and physico-chemical properties like pH. Besides their involvement in desquamation, KLKs may also be important in immune defense and inflammation by processing of mediators and via activation of proteinase-activated receptors (PARs). Aims. 1. To identify and characterize previously unknown proteases in the SC. 2. To further characterize KLK5 and KLK7 with special focus on activation mechanisms. 3. To identify new inhibitors of KLKs in human SC. 4. To further characterize KLKs regarding effects of various inhibitors and substrates. 5. To study possible functions of KLKs in inflammation, in particular via activation of PAR-2. Methods. Plantar SC was used as a source for purification of proteins. Recombinant proteins were produced in different expression systems (insect cells, yeast cells, and bacteria). Different activity assays and kinetic studies were performed. Tissue expression was studied by immunohistochemistry, immunoblot and PCR. PAR-2 activation was studied by measurement of intracellular [Ca2+] and immunofluorescense in KNRK-PAR2 cells. Results. Active KLK14 was purified from extracts of plantar SC. KLK14 showed a superior catalytic efficiency as compared to KLK5 when measuring trypsin-like activity. This indicated that KLK14, despite being present in low amounts in skin, may have great relevance for skin physiology. Among enzymes tested only KLK5 showed autocatalytic activity and is so far the only enzyme found in SC that can activate proKLK7. KLK5 could also activate proKLK14. This together with studies of pH dependence on activation placed KLK5 as a possible key activating enzyme in a proposed proteolytic cascade in the SC. In plantar SC extracts we have also identified the novel Kazal-type serine protease inhibitor 9 (SPINK9). Our results indicate that SPINK9 is preferentially expressed in palmo-plantar skin and specific for KLK5. Differences found regarding substrate specificity and inhibition profile can be useful in evaluating the contribution of individual KLKs to the proteolytic activity in crude SC extracts. One interesting finding was that KLK8, present at high protein levels in the epidermis, could not be inhibited by any protease inhibitor found in the extracts. PAR-2 activation studies showed that KLK5 and 14 but neither KLK7 nor 8 can activate PAR-2. Immunohistochemistry preferentially detected KLK14 in intraepidermal parts of the sweat ducts and in dermal sweat glands but we could also show coexpression of KLK14 and PAR-2 in the SC and stratum granulosum of the epidermis in inflammatory skin disorders. To summarize, KLK involvement in desquamation may be dependent on a proteolytic activation cascade regulated by an intrinsic pH gradient and specific inhibitors present in SC. Another possible function of KLKs is as mediators of inflammation through activation of PAR-2.