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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Clonagem e expressão do fator VII de coagulação sanguínea em linhagens celulares humanas / Cloning and expression of coagulation factor VII in human cell lines

Freitas, Marcela Cristina Corrêa de 29 May 2015 (has links)
O Fator VII recombinante (FVIIr) tem sido a principal escolha terapêutica dos pacientes hemofílicos que desenvolvem inibidores contra os fatores VIII e IX utilizados como tratamento. Atualmente, o produto utilizado é produzido em células de camundongo (BHK-21), o qual oferece desvantagens considerando a complexidade das modificações pós-traducionais desta proteína e a inserção de glicosilações de origem murina altamente imunogênicas aos seres humanos. Dessa maneira a produção de proteínas para uso terapêutico em linhagens celulares humanas surge como uma alternativa promissora. Dentro desse contexto, o objetivo principal deste trabalho foi clonar e expressar o FVII de coagulação sanguínea em 3 linhagens celulares humanas (HepG2, Sk-Hep, HKB-11), compará-las com a linhagem murina BKH-21, e selecionar a melhor produtora da proteína recombinante. As células foram modificadas com o vetor lentiviral p1054-CIGWS, contendo os genes do FVII e do marcador GFP. Após a modificação das células foi observada uma eficiência de transdução de 80% nas células BHK-21-FVIIr, 73% nas células HepG2-FVIIr, 32% nas células HKB-11-FVIIr e 95% Sk-Hep-FVIIr. Análises da expressão gênica por PCR em Tempo Real mostraram que as três linhagens humanas modificadas apresentaram expressão do RNAm relativo ao FVIIr, sendo que a linhagem celular HepG2 foi a que teve maior expressão de FVIIr, seguida da Sk-Hep-1 e HKB-11. Quando submetidas ao tratamento com vitamina K por um período de 10 dias em cultura, a expressão do gene FVIIr foi semelhante para as três linhagens (HepG2: 164563 URE, HKB-11: 119122 URE e Sk-Hep: 124919 URE). O FVII é uma proteína que para sua ativação, possui como principal modificação pós traducional a -carboxilação vitamina K dependente, que ocorre por meio do ciclo da vitamina K com a participação de 3 enzimas, -carboxilase, VKORC1 e calumenina (inibidor). A expressão gênica dessas enzimas foi avaliada antes e após o tratamento com a vitamina K. Foi possível observar que houve um aumento nos níveis de RNAm nas células humanas tratadas com vitamina K, sugerindo que esta é capaz de ativar as enzimas do ciclo da -carboxilação. A cinética de crescimento celular em garrafas estáticas mostrou que a as células murinas BHK-21 modificadas possuem uma velocidade específica de crescimento 25% mais elevada que das células humanas. Contudo a cinética de produção das linhagens recombinantes mostrou que as células humanas produzem cerca de 3 vezes mais FVIIr do as células BHK-21. Devida a baixa produção de FVIIr na linhagem celular murina, e ao fato de que a linhagem humana HepG2 apresenta um perfil de crescimento extremamente lento, as linhagens recombinantes Sk-Hep-1-FVIIr e HKB-11-FVIIr foram selecionadas para ensaios de cultivo em suspensão utilizando microcarregadores em frascos spinners. Ao longo de 10 dias de cultivo as células HKB-11-FVIIr mostraram uma produção acumulada de 152 g de FVIIr, o que corresponde a 304 UI. As células Sk-Hep-1-FVIIr produziram cerca de 202,6 g de FVIIr, o que corresponde a 405,2 UI. Em suma, nossos dados comprovam que as linhagens celulares humanas são eficazes para a produção de fator VII recombinante, uma vez que, utilizando nosso modelo de produção, estas mostraram-se melhores do que a de células murinas (BHK-21) utilizadas pela indústria. Assim, estas linhagens celulares humanas podem ser usadas como uma nova plataforma para a produção de FVII, bem como para outras proteínas recombinantes, de maneira mais segura e com menor risco de desenvolvimento de anticorpos inibidores / Recombinant factor VII (FVIIr) has been the main therapeutic choice for hemophilic patients who develop inhibitors antibidies to conventional treatments (FVIII and FIX). Currently, the comercial product is produced in murine cells (BHK-21) which gives disadvantages considering the complexity of post-translational modifications of these proteins. The insertion of murine residues can be highly immunogenic in humans. Thus the production of proteins for therapeutic use in human cell lines appears as a promising alternative. In this context, the aim of this study was to clone and express the blood coagulation FVII in 3 human cell lines (HepG2, Sk-Hep-1, HKB-11) and select the best cell line for production of recombinant protein. The cells were modified with the lentiviral vector p1054-CIGWS containing the FVII gene and GFP gene marker. After cells modification we observed efficiency of transduction, in which 80% of BHK-21-FVIIr cells showed GFP expression, 73% of HepG2-FVIIr cells, 32% of HKB-11-FVIIr cells and 95% SK- Hep-FVIIr. Gene expression analysis by real-time PCR showed that the three modified human cell lines exhibited RNAm expression relative to FVIIr. When cells were treated with 5 ug/mL vitamin K in culture, the gene expression of FVIIr was similar in the three cell lines (HepG2: 164 563 URE, HKB-11: 119122 and SK-Hep URE: 124919 URE). For FVII activation, the main post translational modification is -carboxylation vitamin-K-dependent which envolves three enzymes, -carboxylase, VKORC1 and calumenina (inhibitor) . Gene expression of these enzymes was evaluated before and after treatment with vitamin K. It was observed that there was an increase in mRNA levels in human cells treated with vitamin K, suggesting that the treatment is capable of activating the enzymes of the vitamin K cycle. Cell growth kinetics showed that modified murine cells BHK-21 have a higher specific growth rate, around 25% more than human cells. However the kinetics of production of recombinant cell lines showed that human cells expressing rFVII 3-fold more rFVII than BHK-21 cells. Due the low rFVII production of murine cells, and the extremely slow growth profile of human cell line HepG2, the recombinant cell lines Sk-Hep-1-rFVII and HKB-11-rFVII have been selected for cultivation tests in suspension using microcarriers in spinners flasks. Over 10 days of cultivation the HKB-11 cells showed a cumulative production of rFVII 152 ug, corresponding to 304 IU and SK-Hep-1 cells showed a rFVII production of 202.6 ug, corresponding to 405.2 IU. In summary, our data demonstrate that human cell lines are effective for producing recombinant factor VII. Using our production model, human cells were better than murine cells (BHK-21) used by the industry. Thus, these human cell lines can be used as a new platform for the FVII production, as well as for other recombinant proteins, with less risk of developing inhibitor antibodies
42

Construção de uma vacina de subunidade proteica de mycobacterium tuberculosis e avaliação da imunogenicidade e antigenicidade / Construction of a protein subunit vaccine mycobacterium tuberculosis and evaluation of immunogenicity and antigenicity

Sousa, Eduardo Martins de 27 March 2013 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-23T13:40:05Z No. of bitstreams: 2 Sousa, Eduardo Martins.pdf: 2216793 bytes, checksum: b28a546dbb9489fa820abe22bc2b6109 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-23T15:17:05Z (GMT) No. of bitstreams: 2 Sousa, Eduardo Martins.pdf: 2216793 bytes, checksum: b28a546dbb9489fa820abe22bc2b6109 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-23T15:17:05Z (GMT). No. of bitstreams: 2 Sousa, Eduardo Martins.pdf: 2216793 bytes, checksum: b28a546dbb9489fa820abe22bc2b6109 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-03-27 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Tuberculosis is a re-emerging infectious disease that remains a major public health problem worldwide. Although there is the BCG vaccine that is effective against severe forms of childhood TB, in adults its efficacy is variable (0-85%). In this context there is a need to develop new vaccines to control the spread of TB. This thesis proposes the development of a new recombinant fusion M. tuberculosis protein (Ag85C-MPT51-HspX) by molecular cloning, expression in E. coli with a histidine tag and purified by ion exchange chromatography. The fusion protein was constructed successfully, expressed in E. coli BL21 and purified. Tests in mice were performed to evaluate the immunogenicity of the recombinant fusion protein Ag85C-MPT51-HspX of M. tuberculosis. Mice were immunized three times with the protein Ag85C-MPT51-HspX formulated with CpG-DNA encapsulated in liposomes, CpG-DNA encapsulated in liposomes, liposome or saline as negative control and the humoral and cellular immune response was evaluated. The immunization with the vaccine formulation induced the production of high titers of specific anti-fusion protein Ag85C-MPT51-HspX IgG1 = 3.08 ± 0.04; IgG2a = 3.10 ± 0.03) and, favored the increase of specific CD4+ IFN-γ (2.14% ± 0.17), CD4+ TNF-α (2.16 ± 0.34%). The recognizing of this protein by seric IgG and IgM discriminated patients with active TB infection from healthy individuals. We conclude that CMX protein has potential to be used for the development of vaccine against M. tuberculosis as well also for TB diagnostic kits. / A tuberculose é uma doença infecciosa re-emergente que permanece como um dos maiores problemas de saúde pública mundial. Embora exista a vacina BCG que é eficiente contra formas graves de TB na infância, em adultos a eficácia é variável (0 a 85%). Nesse contexto existe a necessidade do desenvolvimento de novas vacinas para controlar a disseminação da TB. O presente trabalho teve como objetivo desenvolver uma nova proteína de fusão recombinante (Ag85C-MPT51-HspX) de M. tuberculosis a partir da clonagem molecular, expressão em E. coli com uma cauda de histidina e purificação através de cromatografia de troca iônica. A proteína de fusão foi construída com sucesso expressa em E. coli BL21 e purificada. Ensaios em camundongos foram realizados para avaliar a imunogenicidade da proteína recombinante de fusão Ag85C-MPT51-HspX de M. tuberculosis. Os camundongos foram imunizados três vezes com a proteína Ag85C-MPT51-HspX formulada com CpG-DNA encapsulada em lipossoma, CpG-DNA encapsulado em lipossoma, lipossoma ou salina como controle negativo e a resposta imune humoral e celular foi avaliada . A imunização com a formulação vacinal induziu a produção de altos títulos de anticorpos específicos anti-proteína de fusão Ag85C-MPT51-HspX (IgG1 =3,08±0,04; IgG2a=3,10±0,03), bem como, favoreceu o aumento de células T CD4+IFN-γ (2,14%±0,17), CD4+TNF-α (2,16%±0,34) específicas. A avaliação do reconhecimento desta proteína de fusão tanto por IgM quanto IgG humana sérica permitiu discriminar pacientes com tuberculose ativa de controles saudáveis, demonstrando a antigenicidade desta molécula em humanos. Conclui-se que a proteína CMX poderá ser testada tanto como vacina, assim como para o desenvolvimento de testes de diagnóstico para a tuberculose.
43

Avaliação da imunogenicidade de proteínas recombinantes baseadas em antígenos de diferentes estágios do Plasmodium vivax expressos em Pichia pastoris / Immunogenic evaluation of recombinant proteins expressed in Pichia pastoris based on Plasmodium vivax antigens from different parasite stages

Luciana Chagas de Lima 29 August 2014 (has links)
O Plasmodium vivax é a espécie causadora de malária de maior distribuição mundial e maior prevalência nas Américas. A complexidade do ciclo de vida do parasito e sua extensa diversidade antigênica têm dificultado a obtenção de uma vacina eficaz e inferem que seja pouco provável que este objetivo seja alcançado utilizando um único antígeno. Neste contexto, a combinação de regiões imunodominantes de antígenos de um ou mais estágios do ciclo de vida do Plasmodium pode ser uma estratégia com melhor prognóstico na indução de resposta imune protetora e duradoura contra a atividade parasitária. Este trabalho avaliou a imunogenicidade, em camundongos, de uma formulação vacinal composta pela mistura dos antígenos CSP, pré-eritrocítico e AMA-1, o qual é expresso em ambos os estágios, préeritrocítico e eritrocítico assexuado. A proteína quimérica yPvCSAllFL, que contém epítopos para células B da região central (repeats) das 3 variantes alélicas PvCSP-VK210, PvCSP-VK247 e PvCSP-P. vivax-like fusionados, e a yPvAMA-1 foram expressas com sucesso em leveduras Pichia pastoris e purificadas por métodos cromatográficos para a imunização de camundongos BALB/c e C57BL/6, na presença do adjuvante Poly(I:C), agonista de TLR3. Por ELISA, foram determinados os títulos de anticorpos, as subclasses de IgG e a avidez destes pelas proteínas indutoras, administradas isoladamente ou em combinação. A resposta de anticorpos anti-yPvCSAllFL mostrou ser linhagem dependente, tendo sido observado altos títulos de anticorpos IgG (106) em C57BL/6, os quais se mantiveram elevados por até 6 meses após a última dose. Os anticorpos anti-yPvCSAllFL, predominantemente IgG1, foram capazes de reconhecer proteínas representando as 3 variantes alélicas. No geral, a coadministração dos antígenos yPvCSAllFL e yPvAMA-1 não comprometeu a resposta de anticorpos individual. Utilizando este protocolo de vacinação não foi possível detectar resposta proliferativa de células TCD3+TCD4+ ou TCD3+TCD8+ específicas após a estimulação com yPvCSAllFL. Os índices de proliferação (8,31%) e o padrão de secreção das citocinas IFN-γ, IL-2, TNF-α e IL-10, associados à yPvAMA-1, sofreram redução com a coadministração de antígenos (6,33%) e alteração, com elevação de IL-2 em detrimento das demais citocinas. Os dados gerados no estudo das formulações vacinais apresentadas neste trabalho podem ser úteis para o desenvolvimento de uma vacina anti-P. vivax, principalmente por explorarem estratégias de combinação e fusão de antígenos. / Plasmodium vivax is the species of malaria more widely distributed worldwide and with higher prevalence in the Americas. The complexity of the parasite life cycle and its extensive antigenic diversity have hampered the achievement of an effective vaccine and infer that it is unlikely that this goal will be achieved using a single antigen. In this context, the combination of immunodominant regions of antigens of one or more stages of the Plasmodium life cycle can be a strategy with better prognosis at inducing protective and durable immune responses against this parasite. Our study assessed the immunogenicity of vaccine formulations consisting of mixture of antigens CSP, pre-erythrocytic and AMA-1, which is expressed in the both stages, pre-erythrocytic and erythrocytic asexual, in mice. The chimeric protein yPvCSAllFL, which contains B-cell epitopes of the central region (repeats) of the 3 allelic variants PvCSP-VK210, PvCSP-VK247 and PvCSP-P. vivax-like fused, and the yPvAMA-1 were successfully expressed in the yeast Pichia pastoris and purified by chromatographic methods for immunization of BALB/c and C57BL/6 mice in the presence of the adjuvant Poly(I:C), a TLR3 agonist. By ELISA, we determined the titles, IgG subclasses and the avidity of the antibodies to these proteins, administered alone or in combination. The immune response to yPvCSAllFL proved to be dependent on mouse strain, having been observed high titers of IgG antibodies (106) in C57BL/6, which remained high for up to 6 months after the last dose. Anti-yPvCSAllFL antibodies, predominantly IgG1, were able to recognize proteins representing the 3 allelic variants. In general, the co-administration of yPvCSAllFL and yPvAMA-1 antigens did not compromise the individual antibodies response. Using this vaccination protocol, we could not detect cell specific proliferative responses of TCD3+TCD4+ or TCD3+TCD8+ after stimulation with yPvCSAllFL. The proliferation (8.31%) and the pattern of secretion of cytokines IFN-γ, IL-2, TNF-α and IL-10, associated with the yPvAMA-1, were reduced during the co-administration (6.33%) and compensated by the elevation of IL-2. The data generated on the study of vaccine formulations presented in this thesis may be useful for the development of a vaccine anti-P. vivax, mainly by exploiting strategies of combination and fusion of antigens.
44

Pointillism in Plant Systems Biology: I. Proteomic Analysis of Plant Exosome-like Particles II. Amyloplast-binding Puroindoline Fusion Proteins for Recombinant Protein Expression.

Greenham, Trevor 24 September 2019 (has links)
Expanding upon our understanding of plant defense is critical, particularly with the perilous threats of climate change and overpopulation to our food security, health and well-being. In this study, we focused on plant defense using two distinct approaches. First, we performed a proteomic analysis of plant exosome-like nanoparticles in order to elucidate their defense related protein cargo. Secondly, we used a wheat antimicrobial protein, puroindoline, as a fusion partner for the expression of recombinant proteins in rice endosperm. Plant exosome-like nanoparticles (ELP) were isolated from fresh tomato and subjected to mass spectrometry (MS) analysis. The ELPs were compared to fresh pressed tomato juice, and the proteins that were significantly upregulated in the ELPs were analyzed for their defensive properties. Bioinformatic analysis identified 30 proteins upregulated in the ELPs, with a majority of these being involved in plant defense. Puroindoline is a protein found in soft wheat varieties. A unique feature of this protein is the presence of a tryptophan-rich domain, which causes it to localize and tether onto starch granule surfaces; a property we are seeking to exploit for recombinant protein isolation. We hypothesized that when expressed in a pin-null crop, such as rice, puroindoline along with its fusion partner will localize and adhere to starch granule surfaces. PIN fusions were expressed in rice, and their subcellular localization was determined by immunolocalization. It was observed that PIN localizes to rice starch ii granules in vitro and in planta, and retains its starch granule binding abilities as a fusion partner. To identify other possible starch granule binding fusion partners, an anhydrous cleavage method was developed that can scan dry biological materials for associated proteins, in this case the starch granule surface. Incubation of our cleavage reagent with isolated rice starch granules yielded several cleavage products as determined through SDS-PAGE. These cleavage products were compared with previous proteomic data of trypsin digested rice starch granules.
45

Studium proteas virů Zika a Dengue / Analysis of Zika and Dengue virus proteases

Novotný, Pavel January 2019 (has links)
in English Zika and Dengue flaviviruses are transmitted by mosquitoes in human populations living in tropical areas. They cause fevers which in the case of Dengue can lead to life threatening haemorrhagic form. There is a possible relationship between pregnant women being infected by Zika virus and higher risk of microcephaly in new-borns. The infection is currently treated mainly symptomatically. However, there is an effort to develop compounds which block viral life cycle and viral spread through organism. Viral enzymes, such as flaviviral proteases, are regarded as suitable targets for this effort. These serine proteases with chymotrypsin fold are heterodimers which consist of flaviviral non- structural proteins NS2B and NS3. NS3 domain also contains a helicase, which can be removed by gene recombination for study purposes. NS2B is a transmembrane protein, but only a hydrophilic 40 amino acid peptide is important for the interaction with NS3 domain. This peptide has a chaperon function and participates in substrate binding to the active site. In this study, six variants of recombinant proteins containing activating peptide of NS2B and protease domain of NS3 were expressed and purified. Four variants were characterized in enzymologic studies including testing of possible inhibitors. A dipeptide...
46

Cloning, Expression, and Sequence Analysis of Camelysin, a Zinc Metalloprotease from <em>Bacillus anthracis</em> and <em>B. cereus</em>

Myers, Andrew Ross 18 July 2005 (has links)
Bacillus anthracis and B. cereus are well known etiological agents, which cause disease in healthy and immunocompromised individuals. Considering the abundance and lethality of these organisms it is imperative that research is performed to identify and analyze new factors that may contribute to their pathogenicity. Camelysin is a membrane bound, zinc metalloprotease isolated from B. cereus. Assays performed on purified camelysin demonstrate that the protease exhibits fibrinolytic, collagenolytic, and actin degradation activity, any of which can contribute to the organisms ability to invade host tissues and cause damage. Considering the putative role of camelysin in pathogenicity, it would be beneficial to study the effects of camelysin in tissue cultures or animal models. The goal of this study focused on the cloning and expression of camelysin from B. cereus and its homolog in B. anthracis. Expression of a fusion tagged protein may assist in the purification of camelysin as well as overcoming the native proteins extreme insolubility. Primers were designed to amplify the camelysin gene from B. cereus for cloning into the prokaryotic pBAD TOPO® TA, pET100/D-TOPO®, and the eukaryotic pcDNA3.1/V5-His© TOPO[registered trademark] TA expression vectors. Primers were also designed to amplify the gene from B. anthracis for cloning into the pBAD TOPO® TA vector. The recombinant clones were induced and successful expression of the protein was confirmed by performing SDS-PAGE, Western blotting, and an azocasein protease assay. The recombinant proteins exhibited casein degradation activity which is observed with purified camelysin from B. cereus. This study successfully demonstrated the presence of the camelysin protein in B. anthracis. Furthermore, the recombinant clones obtained will be useful for purification and analysis of camelysin and delineation of its role in the pathogenicity of B. cereus and B. anthracis.
47

Cloning and expression of superoxide dismutase from Sarcoptes scabiei in Escherichia coli

Sanchez Lecaros, Luis January 2006 (has links)
<p>Sarcoptes scabiei is a disease-causing parasitic mite of humans and animals that is prevalent worldwide. The parasite lives in burrows in the epidermis of its host. These burrows are formed by a combination of mechanical destruction by the mite and secretion of various factors.</p><p>The enzyme superoxide dismutase (SOD) catalyzes the dismutation of superoxide into oxygen and hydrogen peroxide. As such, it is an important antioxidant defense in nearly all cells exposed to oxygen. In this project, the enzyme was expressed in transformed Escherichia coli cells. The SOD cDNA from S. scabiei was ligated into two different expression vectors: pPU16 and pET-14b. The S. scabiei SOD open reading frame reported here is 696 nucleotides long and yields a protein with a molecular weight of  69.5 kDa. Only one of the constructs was successfully created, using pPU16. The construct was designated pPU110 and has a sequence coding for a hexahistidine tag downstream of the SOD cDNA and has a sequence coding for the maltose binding protein (MBP) upstream.</p><p>The expression plasmid pPU110 was verified by DNA-sequencing and the tested in different expression experiments. Analysis using SDS-PAGE showed that recombinant fusion SOD could be readily expressed in E.coli.</p>
48

Impact of glucose feed rate on productivity and recombinant protein quality in Escherichia coli

Sandén, Anna Maria January 2005 (has links)
The goal of this work was to contribute to the fed-batch process optimisation task by deriving parameters that have considerable impact on productivity as well as product quality The chosen parameters were I) the design of the glucose feed profile, II) the choice of induction strategy, with respect to the method of addition, and III) the time of the induction, with respect to the specific glucose consumption rate. The present fed-batch experiments using the lacUV5-promoter, for production of b-galactosidase, have shown that a high glucose feed rate gives a specific production rate, qp, that is twice as high, after induction, compared to a feed rate that is 2.5 times lower. The constant accumulation of lacZ-mRNA indicates that the translational capacity is initially limiting the synthesis machinery, but after four hours of maximum specific production and a corresponding drop in lacZ-mRNA production, the cultivation is likely to be transcription limited. The high feed-rate system resulted in high accumulation of β-galactosidase, corresponding to 40% of total cellular proteins. By design of feed profiles in a fed-batch process the detrimental effects of overflow metabolism, giving acetic acid formation, can be avoided. However, the results show that a one-dose addition of isopropyl-β-D-galactopyranoside (IPTG), provokes a non-growth associated production of acetic acid. This response can be alleviated by; lowering the inducer concentration (in this case to below 165 μM), by further reducing the feed rate of glucose or by using alternative induction methods. The use of a stepwise addition or a feed of IPTG thus delayed and reduced the level of acetic acid accumulation. It was also shown that a small change in the time-point of induction lead to large variability, regarding both productivity and acetic acid accumulation, in a fed-batch cultivation, In order to further investigate the protein quality two additional proteins were studied in fed-batch cultivations using high and low glucose feed. The aim was to prove the hypothesis that the feed related change in the rate of synthesis of the nascent polypeptide controls the product quality. For the two proteins: Zb-MalE (wt) and Zb-MalE31 (mutant), the transcription rate, in terms of amount of IPTG, and translation rate, in terms of changes in feed rate, influences the percentage of inclusion body formation and degradation of nascent polypeptide. The data show a higher rate of inclusion body formation for the model protein Zb-MalE31 during high feed rate cultivations, as well as at high levels of inducer. Furthermore, the rate of proteolysis was significantly higher for a high feed rate. The high feed rate thus results in a higher rate of synthesis but a lower corresponding quality, for the model proteins studied. In the present investigation of fed-batch cultivations using several different expression vectors, it was found that the central alarmone guanosine tetraphosphate (ppGpp) was formed at both high and low feed rates upon induction. It could be shown, however, that by secretion of Zb-MalE to the periplasm, the stringent response could be avoided. This might be due to the decreased burden on the host where the secretion of product further seems to make the cell able to redirect the carbon flux from overflow metabolism, since no acetic acid was produced. The secretion also demonstrates that the growth arrest could be aborted, which is otherwise gained in the PmalK production system. A novel fed-batch process based on the promoters for the universal stress proteins A and B (PuspA, PuspB) was designed to make use of these powerful promoters in an industrial production context. It was concluded that the process had to start from a high specific growth rate and induction was performed once a limiting feed started. This was done to purposely induce the stringent response and/or acetic acid accumulation since this was required for induction. In the suggested system, induction has to be performed and maintained at continuous substrate feeding, whilst avoiding exceeding the cellular capacity, since the stationary phase starvation alone did not lead to production. In conclusion, a new stress induction based production system was achieved resulting in high accumulations of product protein without any detected metabolic side effects. / <p>QC 20101008</p>
49

Recombinant Transglutaminase Production By Metabolically Engineered Pichia Pastoris

Gunduz, Burcu 01 September 2012 (has links) (PDF)
Transglutaminases (EC 2.3.2.13) are enzymes that catalyze an acyl transfer reaction between a &gamma / -carboxyamide group of a peptide bound glutaminyl residue (acyl donor) and a variety of primary amines (acyl acceptors), including the amino group lysine. Transglutaminase has a potential in obtaining proteins with novel properties, improving nutritional quality of foods with the addition of essential amino acids, preparing heat stable gels, developing rheological properties and mechanical strength of foods and reducing the applications of food additives. The aim of this study is to develop intracellular and extracellular microbial protransglutaminase (pro-MTG) producing recombinant Pichia pastoris strains by using genetic engineering techniques. In this context first,protransglutaminase gene (pro-mtg) from Streptomyces mobaraensis was amplified by PCR both for intracellular and extracellular constructs using proper primers then they were cloned into the pPICZ&alpha / -A expression vectors, separately. Both intracellular (pPICZ&alpha / A::pro-mtgintra) and extracellular (pPICZ&alpha / A::pro-mtgextra) constructs were prepared with strong alcohol oxidase 1 promoter which is induced by methanol. Pichia pastoris X33 cells were transfected by linear pPICZ&alpha / A::pro-mtgintra and pPICZ&alpha / A::pro-mtgextra, separately and plasmids were integrated into the Pichia pastoris X33 genome at AOX1 locus. After constructing the recombinant P. pastoris strains, batch shaker bioreactor experiments were performed for each recombinant cell and the best producing strains were selected according to Dot blot and SDS-PAGE analyses. The selected recombinant P. pastoris strains, carrying pPICZ&alpha / A::promtgextra gene and pPICZ&alpha / A::pro-mtgintra gene in their genome were named as E8 and I1, respectively. Afterwards, a controlled pilot scale bioreactor experiment in a working volume of 1 L was performed with E8 clone and produced pro-MTG was activated by Dispase I. The variations in the recombinant MTG activity, cell concentration, total protease activity, AOX activity and organic acid concentrations throughout the bioprocess were analyzed and specific growth rates, specific consumption rates and yield coefficients were calculated regarding to measured data. Maximum MTG activity was obtained as 4448 U L- 1 and the maximum cell concentration was measured as 74.1 g L-1 at t=36 h of the bioprocess. In this study, an active transglutaminase enzyme was produced extracellularly by P. pastoris for the first time and the third highest extracellular MTG activity was achieved with E8 clone.
50

Cloning and expression of superoxide dismutase from Sarcoptes scabiei in Escherichia coli

Sanchez Lecaros, Luis January 2006 (has links)
Sarcoptes scabiei is a disease-causing parasitic mite of humans and animals that is prevalent worldwide. The parasite lives in burrows in the epidermis of its host. These burrows are formed by a combination of mechanical destruction by the mite and secretion of various factors. The enzyme superoxide dismutase (SOD) catalyzes the dismutation of superoxide into oxygen and hydrogen peroxide. As such, it is an important antioxidant defense in nearly all cells exposed to oxygen. In this project, the enzyme was expressed in transformed Escherichia coli cells. The SOD cDNA from S. scabiei was ligated into two different expression vectors: pPU16 and pET-14b. The S. scabiei SOD open reading frame reported here is 696 nucleotides long and yields a protein with a molecular weight of  69.5 kDa. Only one of the constructs was successfully created, using pPU16. The construct was designated pPU110 and has a sequence coding for a hexahistidine tag downstream of the SOD cDNA and has a sequence coding for the maltose binding protein (MBP) upstream. The expression plasmid pPU110 was verified by DNA-sequencing and the tested in different expression experiments. Analysis using SDS-PAGE showed that recombinant fusion SOD could be readily expressed in E.coli.

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