Rhodococcus is an important industrial organism that possesses diverse metabolic capabilities, it also has a unique cell envelope, composed of an outer layer of mycolic acids and glycolipids (free or bound lipids generally linked to the sugar trehalose). Rhodococcus is able to transform nitriles to the corresponding amide by the enzyme Nitrile Hydratase (NHase), therefore rhodococcal cells can be utilized as biocatalysts in the detoxification of nitrile waste water or in the production of industrially important amides such as acrylamide. However, the NHase within the native cells must be stable with high activity. This research examined how NHase activity and stability can be increased in native cells by changing growth media composition, the impact on the rhodococcal cell envelope was also studied. Growth media composition was altered by supplementing different sugars such as fructose, maltose or maltodextrin to replace glucose in rich solid media containing cobalt and urea for induction of NHase. The supplementation of maltose or maltodextrin resulted in significantly higher NHase activities and greater NHase stability at 55„aC. The supplementation of these different sugars was shown to alter cellular and lipid bound trehalose levels, a sugar known to stabilize proteins and a component of the rhodococcal cell envelope. Cells that had higher levels of cellular trehalose had significantly greater NHase stability at 55„aC. The effect of the different sugar supplements and inducers of NHase, such as cobalt, on cell envelope components such as mycolic acids and glycolipids were examined by High Performance Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC). The results showed that changes in mycolic acids and glycolipids occurred when the cells were grown in the presence of different sugar supplements and when the cells were induced for NHase. Susceptibility of Rhodococcus sp DAP 96253 to different antibiotics was examined to indicate if changes were occurring in the cell envelope. Differences in antibiotic susceptibility were observed when the cells were grown on media with different sugar supplements and when the cells were induced for NHase. In the presence of cobalt Rhodococcus sp DAP 96253 showed a significant increase in sensitivity to antibiotics. Changes in growth media composition influences the cell envelope of Rhodococcus sp DAP 96253 and also affects NHase activity and stability. Therefore, achieving increased enzyme activity and stability is not entirely dependent on the actual enzyme, but is related to other aspects of the cell, such as the cell envelope and metabolites of the cell.

Cyanide is acutely toxic to the environment. However, this simple nitrile is used in several industrial applications especially the mining industry. Due to its high affinity to metals, cyanide has been used for years to extract gold and other precious metals from the ore. Cyanide nitrilases are considered for the detoxification of the industrial wastewaters contaminated with cyanide. Their application in cyanide remediation promises cheaper and safer processes compared to chemical detoxification. However, application of these enzymes in industry requires improving their characteristics. The goal of this dissertation is to better understand cyanide nitrilases, in particular the cyanide dihydratase from of Bacillus pumilus and Pseudomonas stutzeri and to improve their activity and stability. The lack of any high resolution structure of these enzymes calls for isolating or screening for mutants showing enhancement in enzyme properties. Described first is a simple and efficient method utilizing in vivo recombination to create recombinant libraries incorporating the products of PCR amplification. This method is useful for generating large pools of randomly mutagenized clones after error-prone PCR mutagenesis. Several parameters were investigated to optimize this technique; length of homology region, vector treatment, induction time and ratio of fragment to vector. Using error-prone PCR for random mutagenesis, several CynDpum mutants were isolated for higher catalysis at pH 7.7. Three point mutations, K93R, D172N and E327K increased the enzyme’s thermostability. The D172N mutation also increased the affinity of the enzyme for its substrate at pH 7.7 suggesting an effect on the active site. However, the A202T mutation located in the dimerization or the A surface rendered the enzyme inactive by destabilizing it. No significant effect on activity at alkaline pH was observed for any of the purified mutants. Lastly, an important region for CynDstut activity was identified in the C-terminus. This same region increased the stability of CynDpum compared to the wild-type enzyme. Also, CynDpum-stut hybrid was found to be highly more stable than CynDpum. This same hybrid exhibited 100% activity at pH9, a pH where the parent enzyme is inactive, and retained 40% of its activity at pH 9.5 making it a true pH tolerant mutant.

Universiẗat, Diss., 2004--Düsseldorf.

Introduction: Uterine fibroids are the most common benign tumours of female genital tract with the peak incidence in the 4th and 5th decennium. The aetiology of uterine fibroids still remains poorly understood. Genetic factors play undisputed role in the onset of uterine fibroids. Up to date numerous gene mutations were identified in certain percentage of patients with uterine fibroids. One of the candidate genes is Fumarate hydratase gene (FH). Heterozygous germiline mutations of FH cause two hereditary syndromes: Multiple smooth muscle tumours of the skin and uterus (MCUL1)/ Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) characterised by leiomyomata of the skin, early onset uterine fibroids between 20-30 years of age and renal papillary carcinoma. The aim of our thesis was to identify the frequency of FH mutations in patients with early onset sporadic uterine fibroids. Methods: Patients with the diagnosis of uterine fibroids up to the age of 30 years were enrolled in the study. Control group consisted of patients with absence of uterine fibroids. Activities of Fumarate hydratase and control protein Citrate synthase were measured in lymphocytes and compared to the results obtained from the healthy controls. Mutation analysis of FH gene was performed. Activity of Fumarate...

Abstract The peroxisomal multifunctional enzyme type-1 (perMFE-1) is a monomeric protein of β-oxidation possessing 2-enoyl-CoA hydratase-1, Δ3-Δ 2-enoyl-CoA isomerase, and (3S)-hydroxyacyl-CoA dehydrogenase activities. The amino-terminal part of perMFE-1 shows sequence similarity to mitochondrial 2-enoyl-CoA hydratases (ECH-1) and Δ3-Δ 2-enoyl-CoA isomerases, and belongs to the hydratase/isomerase superfamily. Family members with known structures are either homotrimers or homohexamers. The purpose of this work was to elucidate the structure-function relationship of the rat perMFE-1 with special reference to the hydratase/isomerase fold. The structural adaptations required for binding of a long chain fatty acyl-CoA were studied with rat ECH-1 via co-crystallization with octanoyl-CoA. The crystal structure revealed that the long chain fatty acyl-CoA is bound in an extended conformation. This is possible because, a flexible loop moves aside and opens a tunnel, which traverses the subunit from the solvent space to the intertrimer space. Structural and enzymological studies have shown the importance of Glu144 and Glu164 for the catalysis by ECH-1. In the present work the enzymological properties of Glu144Ala and Glu164Ala variants of ECH-1 were studied. The catalytic activity of hydration was reduced about 2000-fold. It was also demonstrated that rat ECH-1 is capable of catalyzing isomerization. The replacement of Glu164 with alanine reduced the isomerase activity 1000-fold, confirming the role of Glu164 in both the hydratase and isomerase reactions. The structural factors favoring the hydratase over the isomerase reaction were addressed studying the enzymological properties of the Gln162Ala, Gln162Met, and Gln162Leu variants. These mutants had similar enzymatic properties to wild type, thus the catalytic function of the Glu164 side chain in the hydratase and isomerase reaction does not depend on interaction with the Gln162 side chain. The perMFE-1 was divided into five functional domains based on amino acid sequence comparisons with the homologous proteins with known structures. Deletion variants of perMFE-1 showed that the folding of an enzymatically active amino-terminal hydratase/isomerase domain requires stabilizing interactions from the two carboxy-terminal domains of perMFE-1. The last carboxy-terminal domain is also required for the folding of the dehydrogenase part of perMFE-1. The dehydrogenase part of perMFE-1 was crystallized.

Abstract Interest in off-pump coronary surgery and ischaemic preconditioning has been increasing. The aim of this study was to evaluate surrogate indicators of haemodynamic, myocardial, and cerebral outcome during off-pump surgery and preconditioning. Haemodynamics and myocardial preservation were monitored in a pilot study of twelve patients undergoing off-pump coronary surgery. Indicators of myocardial metabolism and tissue injury as well as cerebral damage were evaluated in a randomized study of thirty-three patients undergoing on-pump (11) or off-pump surgery with (11) or without (11) preceding myocardial ischaemic preconditioning for five minutes followed by reperfusion for five minutes. The pilot study showed minimal haemodynamic changes and myocardial derangements during off-pump surgery as evaluated intraoperatively based on transcardiac differences of ATP degradation products and lactate and postoperatively based on MB mass of creatine kinase and troponin T. In the following studies, myocardial ischaemic metabolism was evaluated intraoperatively by measuring transcardiac differences of ATP degradation products, lactate, and pH, which increased significantly from the baseline values in all study groups. However, the maximum values of lactate and pH were significantly higher in the cardiopulmonary bypass group (p = 0.02 and p = 0.007, respectively). There were no statistical differences between the preconditioning and non-preconditioning groups. Myocardial tissue injury was evaluated by postoperative leakage of MB mass of creatine kinase and troponin I. Their peak values were significantly higher (p < 0.001 and p = 0.008) after cardiopulmonary bypass (15.1 μg/l and 13.8 μg/l) than after off-pump surgery without preconditioning (6.3 μg/l and 5.2 μg/l). The respective values were 14.8 μg/l and 7.4 μg/l after preconditioning, and there were no statistically significant differences between the off-pump groups with and without preconditioning. Cerebral damage was evaluated based on the intra- and postoperative serum concentrations of neuron-specific enolase, which were corrected with respect to haemolysis. The corrected values were significantly higher after on-pump than off-pump surgery (p = 0.003 and p = 0.005). In conclusion, multi-vessel off-pump coronary artery surgery is a haemodynamically feasible procedure offering better myocardial preservation compared to on-pump surgery. Ischaemic preconditioning of the myocardium does not seem to improve myocardial preservation in off-pump surgery. The slightly lower levels of neuron-specific enolase also suggest less cerebral damage.

Objetivo: este estudo objetivou avaliar a presença do anticorpo anti-alfaenolase (AAAE) IgM na doença de Behçet (DB) e suas possíveis associações com as manifestações clínicas e atividade da doença. Métodos: noventa e sete pacientes com DB foram comparados a 36 pacientes com enteroartrite (EA) [24 com doença de Crohn (DC) e 12 com retocolite ulcerativa (RCU)], além de 87 controles saudáveis. Os testes para detecção do AAAE IgM foram realizados por Immunoblotting. A atividade de doença foi avaliada por índices padronizados, como o Formulário de Atividade Atual da Doença de Behçet (BR-BDCAF) para os pacientes com DB e o Índice de Harvey-Bradshaw (HBI) para os pacientes com DC e RCU. Uma segunda avaliação foi realizada somente nos pacientes com DB (n=56) para a detecção do AAAE IgM, avaliação de atividade de doença e dosagem de proteína-C-reativa (PCR). Resultados: maior prevalência do AAAE IgM foi encontrada na DB (17,7%) comparativamente à EA (2,8%) e aos controles saudáveis (2,3%), p < 0,001. A frequência do AAAE IgM foi maior na DB ativa quando comparada à DB inativa (30,2% vs. 7,4%, p=0,006). Este achado foi confirmado em uma segunda avaliação de 56 pacientes do grupo com DB (45,5% vs. 13,3%, p=0,02). A média do BR-BDCAF foi maior no grupo com AAAE IgM positivo, em ambas avaliações (9,1 ± 5,4 vs. 4,9 ± 4,9, p=0,002; 5,0 ± 4,9 vs. 2,2 ± 2,9, p=0,01, respectivamente). Os pacientes com DB em atividade mucocutânea e articular apresentaram maior incidência do AAAE IgM, tanto na primeira quanto na segunda avaliação (64,7% vs. 27,5%, p=0,005; 36,4% vs. 7,1%, p=0,039, respectivamente). Conclusões: os presentes dados corroboram que a alfa-enolase é um antígeno alvo na DB, particularmente associada à atividade mucocutânea e articular da doença. Além disso, o AAAE IgM pode distinguir a DB da EA, especialmente em pacientes com alta atividade de doença / Objective: this study aimed to assess IgM AAEA in systemic Behçet\'s disease (BD) and its possible association with clinical manifestations and disease activity. Methods: ninety-seven consecutively selected BD patients were compared to 36 enteropathic spondyloarthritis (ESpA) [24 Crohn\'s disease (CD) and 12 ulcerative colitis (UC)] patients and 87 healthy controls. IgM AAEA was detected by Immunoblotting. Disease activity was assessed by standardized indexes, Brazilian BD Current Activity Form (BR-BDCAF) for BD and Harvey-Bradshaw Index (HBI) for CD and UC patients. A second evaluation was performed in BD patients (n=56), regarding IgM AAEA presence, disease activity scores and C-reactive protein (CRP). Results: higher IgM AAEA prevalence was found in BD (17.7%) compared to ESpA (2.8%) and healthy controls (2.3%), p < 0.001. IgM AAEA frequency was higher in active BD compared to inactive BD (30.2% vs. 7.4%, p=0.006), a finding confirmed in the second cross-sectional evaluation of 56 of these BD patients (45.5% vs. 13.3%, p=0.02). Mean BR-BDCAF scores were higher in IgM AAEA positive group on both evaluations (9.1 ± 5.4 vs. 4.9 ± 4.9, p=0.002; 5.0 ± 4.9 vs. 2.2 ± 2.9, p=0.01, respectively). BD patients with mucocutaneous and articular symptoms presented higher IgM AAEA positivity in the first and second evaluations (64.7% vs. 27.5%, p=0.005; 36.4% vs. 7.1%, p=0.039 respectively). Conclusions: these data support the notion that alpha-enolase is a target antigen in BD, particularly associated with disease activity, mucocutaneous and articular involvement. In addition, IgM AAEA may distinguish BD from ESpA, especially in patients with high disease activity

Introduction: Uterine fibroids are the most common benign tumours of female genital tract with the peak incidence in the 4th and 5th decennium. The aetiology of uterine fibroids still remains poorly understood. Genetic factors play undisputed role in the onset of uterine fibroids. Up to date numerous gene mutations were identified in certain percentage of patients with uterine fibroids. One of the candidate genes is Fumarate hydratase gene (FH). Heterozygous germiline mutations of FH cause two hereditary syndromes: Multiple smooth muscle tumours of the skin and uterus (MCUL1)/ Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) characterised by leiomyomata of the skin, early onset uterine fibroids between 20-30 years of age and renal papillary carcinoma. The aim of our thesis was to identify the frequency of FH mutations in patients with early onset sporadic uterine fibroids. Methods: Patients with the diagnosis of uterine fibroids up to the age of 30 years were enrolled in the study. Control group consisted of patients with absence of uterine fibroids. Activities of Fumarate hydratase and control protein Citrate synthase were measured in lymphocytes and compared to the results obtained from the healthy controls. Mutation analysis of FH gene was performed. Activity of Fumarate...

La protéine kinase activée par AMP (AMPK) est un senseur et régulateur central de l'état énergétique cellulaire, mais ces voies de signalisation ne sont pour le moment que partiellement comprises. Deux criblages non-biaisés pour la recherche de partenaires d'interaction et de substrats d'AMPK ont précédemment été réalisés dans le laboratoire. Ces derniers ont permis l'identification de plusieurs candidats (protéines), mais leur rôle fonctionnel et physiologique n'était pas encore établi. Ici nous avons caractérisé la fonction de la relation entre AMPK et quatre partenaires d'interaction : gluthation S-transferases (GSTP1 and GSTM1), fumarate hydratase (FH), l'E3 ubiquitine-ligase (NRDP1), et les protéines associées à la membrane (VAMP2 and VAMP3). Chacune de ces interactions parait avoir un rôle différent dans la signalisation AMPK, agissant en amont ou en aval de la protéine AMPK. GSTP1 et GSTM1 contribueraient à l'activation d'AMPK en facilitant la S-glutathionylation d'AMPK en conditions oxydatives moyennes. Cette régulation non-canonique suggère que l'AMPK peut être un senseur de l'état redox cellulaire. FH mitochondrial est l'unique substrat AMPK clairement identifié. Etonnamment le site de phosphorylation se trouve dans le peptide signal mitochondrial, ce qui pourrait affecter l'import mitochondrial. NRDP1, protéine pour laquelle nous avons pour la première fois développé un protocole de production de la protéine soluble, est faiblement phosphorylée par l'AMPK. L'interaction ne sert pas à l'ubiquitination d'AMPK, mais affecte le renouvellement de NRDP1. Finalement, l'interaction de VAMP2/3 avec AMPK n'implique pas d'évènement de phosphorylation ou d'activation d'un des partenaires. Nous proposons un mécanisme de recrutement d'AMPK par VAMP2/3 (" scaffold ") au niveau des vésicules en exocytose. Ce recrutement favoriserait la phosphorylation de substrats de l'AMPK à la surface des vésicules en exocytoses. Une fois mis en commun, nos résultats enrichissent les connaissances sur les voies de signalisation AMPK, et suggèrent une grande complexité de ces dernières. Plus que les kinases en amont et des substrats en aval, la régulation de la signalisation d'AMPK se fait via des modifications secondaires autres que la phosphorylation, via des effets sur le renouvellement de protéines, et probablement via un recrutement spécifique de l'AMPK dans certains compartiments cellulaires. / AMP-activated protein kinase (AMPK) is a central energy sensor and regulator of cellular energy state, but the AMPK signaling network is still incompletely understood. Two earlier non-biased screens for AMPK interaction partners and substrates performed in the laboratory identified several candidate proteins, but functional and physiological roles remained unclear. Here we characterized the functional relationship of AMPK with four different protein interaction partners: gluthatione S-transferases (GSTP1 and GSTM1), fumarate hydratase (FH), an E3 ubiquitin-ligase (NRDP1), and vesicle-associated membrane proteins (VAMP2 and VAMP3). Each of these interaction partners seems to have a different function in AMPK signaling, either acting up- or down-stream of AMPK. GSTP1 and GSTM1 can contribute to AMPK activation by facilitating S-glutathionylation of AMPK under mildly oxidative conditions. This non-canonical regulation suggests AMPK as a sensor of cellular redox state. Mitochondrial FH was identified as the only clear AMPK downstream substrate, but surprisingly the phosphorylation site is present in the mitochondrial targeting prepeptide, possibly affecting mitochondrial import. NRDP1, whose expression as a full-length soluble protein was achieved here for the first time, is phosphorylated by AMPK only at low levels. The interaction does neither serve for AMPK ubiquitinylation, but rather affects NRDP1 turnover. Finally, interaction of VAMP2/3 with AMPK does not involve phosphorylation or activation events of one of the partners. Instead, we propose VAMP2/3 as scaffolding proteins that recruit AMPK to exocytotic vesicles which could favor phosphorylation of vesicular AMPK substrates for exocytosis. Collectively, our results add some new elements to the AMPK signaling network, suggesting that it is much more complex than anticipated. In addition to upstream kinases and downstream substrates, regulation of AMPK signaling occurs by second

Trypanosoma cruzi é um protozoário flagelado que ao infectar seres humanos causa a doença de Chagas, uma doença tropical negligenciada que afeta milhões de pessoas no mundo todo. As fumarato hidratases (FH), ou fumarases, são enzimas que catalisam a reação estéreo-específica reversível de hidratação do fumarato em S-malato, e foram recentemente consideradas essenciais para a viabilidade do parasito Trypanosoma brucei, sugerindo seu potencial como alvo macromolecular para o desenvolvimento de novos fármacos tripanocidas. O presente trabalho visou à caracterização funcional, bioquímica, biofísica e estrutural das fumarases de T. cruzi (TcFHs) e humana (HsFH) de forma a avaliar o papel das TcFHs para o parasito Trypanosoma cruzi, mapear o mecanismo de ação e identificar as diferenças entre TcFHs e a enzima humana de forma a serem exploradas no planejamento de inibidores seletivos às fumarases do parasito. Análise das sequências mostrou que TcFHs pertencem à classe I das fumarases (enzimas diméricas dependentes de ferro) e não são homólogas à HsFH que pertence a classe II (tetraméricas independentes de ferro). Estudos de localização celular confirmaram a existência de duas fumarases em T. cruzi, uma citosólica (TcFHc) e uma mitocondrial (TcFHm), e experimentos de nocaute gênico sugeriram que essas enzimas são essências para o parasito. A caracterização cinética das enzimas TcFHc, TcFHm e HsFH mostrou que as fumarases de T. cruzi são sensíveis ao oxigênio enquanto a enzima humana se mantém ativa em condições aeróbicas. Estudos de ressonância eletrônica paramagnética mostraram a presença de um cluster de ferro-enxofre, sensível a oxidação por oxigênio, envolvido no mecanismo enzimático das enzimas TcFHs. Modelos estruturais das TcFHs, construídos por homologia à estrutura cristalográfica da fumarase de Leishmania major, foram comparados à estrutura cristalográfica obtida para a fumarase humana e as diferenças entre as duas estruturas foram utilizadas no planejamento de ligantes seletivos às fumarases do parasito. O ligante planejado inibiu a fumarase citosólica de T. cruzi na faixa de 1 ?M e não apresentou efeito na atividade da enzima humana. Testes in vivo demonstraram o efeito tripanocida do inibidor provavelmente por interferir na produção de ATP pela mitocôndria do T. cruzi. Os resultados obtidos com o desenvolvimento desse projeto apresentam uma proposta inovadora no desenvolvimento de novas terapias contra a doença de Chagas, o uso da enzima fumarase como alvo macromolecular, assim como apresenta um inibidor potente e seletivo para a enzima do parasito a ser utilizado como protótipo no desenvolvimento de fármacos contra Trypanosoma cruzi. A síntese de moléculas análogas ao inibidor de forma a melhorar suas propriedades farmacológicas encontra-se em andamento / Trypanosoma cruzi is a flagellate protozoan parasite that infects humans and causes Chagas disease, a tropical neglected disease that affects millions of people worldwide. Fumarate hydratases (FH), or fumarases, are enzymes responsible for the reversible stereo-specific hydration of fumarate into S-malate, and were recently considered to be essential to Trypanosoma brucei viability, suggesting, therefore, a potential role for FHs as macromolecular targets to the drug development against trypanosomatids. The present work focused on the functional, biochemical, biophysical and structural characterization of T. cruzi fumarases (TcFHs) and human fumarase (HsFH) to evaluate TcFHs role for T. cruzi, map the reaction mechanism and identify and exploit differences between the parasite and host enzymes in order to design selective inhibitors to the parasite enzyme. Sequence analysis revealed that TcFHs belong to class I fumarases (dimeric and iron-sulfur containing enzymes) and are not homologous to HsFH which belongs to class II fumarases (tetrameric iron independent enzymes). Cellular sub-localization studies confirmed the presence of a cytosolic and a mitochondrial fumarases in T. cruzi and gene knockout experiments suggested TcFHs are essential to the parasite. The kinetic characterization showed that TcFHs activity is highly sensitive to oxygen whereas HsFH activity remained stable in aerobic conditions. Electron paramagnetic experiments further revealed the presence of an iron-sulfur cluster highly sensitive to oxidation and involved in the catalytic mechanism in both TcFHm and TcFHc. TcFHs structural models, built by homology modeling using the Leishmania major fumarase crystal structure as template, were compared to the HsFH crystal structure and the differences were used to design a selective ligand to the parasite fumarases. The designed ligand showed to inhibit TcFHc with an IC50 of 1 ?M and showed no effect on the human fumarase activity. In vivo assays using T. cruzi epimastigotes demonstrated the trypanocidal effect of the designed inhibitor probably caused by stalling ATP production. The results obtained with the development of this project represent an innovative proposal on the development of new therapies against Chagas disease, the use of fumarase enzyme as a macromolecular target, as well as present a potent and selective inhibitor to the parasite enzyme to be further used as a prototype in the development of drugs against Chagas disease. The synthesis of inhibitor analogues with optimized pharmacological properties are currently in progress.