Base de dados : LILACS
Pesquisa : G02.206 [Categoria DeCS]
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Id: biblio-1015847
Autor: Dapkunas, Zilvinas; Baranauskas, Aurimas; Mickiene, Gitana; Pleckaityte, Milda; Zvirblis, Gintautas.
Título: Generation of dimeric single-chain antibodies neutralizing the cytolytic activity of vaginolysin
Fonte: Electron. j. biotechnol;28:52-57, July. 2017. ilus, graf, tab.
Idioma: en.
Projeto: Research Council of Lithuania.
Resumo: Background: Gardnerella vaginalis is a bacterial vaginosis (BV)-associated vaginal bacterium that produces the toxin vaginolysin (VLY). VLY is a pore-forming toxin that is suggested to be the main virulence factor of G. vaginalis. The high recurrence rate of BV and the emergence of antibiotic-resistant bacterial species demonstrate the need for the development of recombinant antibodies as novel therapeutic agents for disease treatment. Single-chain variable fragments (scFvs) generated against VLY exhibited reduced efficacy to neutralize VLY activity compared to the respective full-length antibodies. To improve the properties of scFvs, monospecific dimeric scFvs were generated by the genetic fusion of two anti-VLY scFv molecules connected by an alpha-helix-forming peptide linker. Results: N-terminal hexahistidine-tagged dimeric scFvs were constructed and produced in Escherichia coli and purified using metal chelate affinity chromatography. Inhibition of VLY-mediated human erythrocyte lysis by dimeric and monomeric scFvs was detected by in vitro hemolytic assay. The circulating half-life of purified scFvs in the blood plasma of mice was determined by ELISA. Dimeric anti-VLY scFvs showed higher neutralizing potency and extended circulating half-life than parental monomeric scFv. Conclusions: The protein obtained by the genetic fusion of two anti-VLY scFvs into a dimeric molecule exhibited improved properties in comparison with monomeric scFv. This new recombinant antibody might implement new possibilities for the prophylaxis and treatment of the diseases caused by the bacteria G. vaginalis.
Descritores: Proteínas de Bactérias/imunologia
Toxinas Bacterianas/imunologia
Anticorpos Neutralizantes/metabolismo
Anticorpos de Cadeia Única/metabolismo
-Proteínas de Bactérias/toxicidade
Toxinas Bacterianas/toxicidade
Ensaio de Imunoadsorção Enzimática
Gardnerella vaginalis
Vaginose Bacteriana
Dimerização
Fatores de Virulência
Fusão Gênica
Anticorpos Neutralizantes/imunologia
Anticorpos de Cadeia Única/imunologia
Meia-Vida
Limites: Animais
Camundongos
Responsável: CL1.1 - Biblioteca Central


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Id: biblio-835096
Autor: Perazzo, Florencia.
Título: Pertuzumab, primer inhibidor de la dimerización HER / Pertuzumab, first HER dimerization inhibitor
Fonte: Oncol. clín;18(1):1-13, mar. 2013. ilus, tab, graf.
Idioma: es.
Resumo: Entre un 15 y un 20% de pacientes con cáncer de mama presentan amplificación o sobre expresión de HER2, lo que le confiere un comportamiento más agresivo. Pese a que el advenimiento del trastuzumab, primer agente dirigido contra HER2, mejoró significativamente el pronóstico de este grupo de pacientes, el 50% de ellas aún progresa dentro del año de tratamiento. Pertuzumab, el primer inhibidor de la dimerización de HER2, muestra un mecanismo de acción complementario a trastuzumab, logrando mejores resultados clínicos en pacientes tratadas con ambos agentes anti-HER2 y quimioterapia. El presente trabajo repasa las propiedades de pertuzumab y su desarrollo clínico.

Approximately 15 to 20% of breast cancers present amplificationor overexpression of HER2, and these tumoursshow a more aggressive behavior. Trastuzumab, the firsttargeted agent against HER2, significantly improved prognosisfor these patients, but still around 50% shows diseaseprogression within the first year of treatment. Pertuzumab,the first HER2 dimerization inhibitor, has a mechanismof action that is complementary to that of trastuzumab,achieving enhanced efficacy for patients treated with bothanti-HER2 agents and chemotepapy. This work reviews themain aspects of pertuzumab and its clinical development.
Descritores: Mama
Neoplasias da Mama
Fator de Crescimento Epidérmico
Neoplasias
-Dimerização
Metástase Neoplásica
Prognóstico
Qualidade de Vida
Sobrevida
Terapêutica
Limites: Seres Humanos
Responsável: AR144.1 - CIBCHACO - Centro de Información Biomedica del Chaco


  3 / 15 LILACS  
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Id: lil-751309
Autor: Pereira, Elisângela Vitoriano; Costa, Jorge de Assis; Alfenas, Rita de Cássia Gonçalves.
Título: Effect of glycemic index on obesity control
Fonte: Arch. endocrinol. metab. (Online);59(3):245-251, 06/2015. tab, graf.
Idioma: en.
Resumo: Objective Evaluate the effect of glycemic index (GI) on biochemical parameters, food intake, energy metabolism, anthropometric measures and body composition in overweight subjects.Materials and methods Simple blind study, in which nineteen subjects were randomly assigned to consume in the laboratory two daily low GI (n = 10) or high GI (n = 9) meals, for forty-five consecutive days. Habitual food intake was assessed at baseline. Food intake, anthropometric measures and body composition were assessed at each 15 days. Energy metabolism and biochemical parameters were evaluated at baseline and the end of the study.Results Low GI meals increased fat oxidation, and reduced waist circumference and HOMA-IR, while high GI meals increased daily dietary fiber and energy intake compared to baseline. There was a higher reduction on waist circumference and body fat, and a higher increase on postprandial fat oxidation in response to the LGI meals than after high GI meals. High GI meals increased fasting respiratory coefficient compared to baseline and low GI meals.Conclusion The results of the present study showed that the consumption of two daily low GI meals for forty-five consecutive days has a positive effect on obesity control, whereas, the consumption of high GI meals result has the opposite effect. Arch Endocrinol Metab. 2015;59(3):245-51.
Descritores: Proteínas de Bactérias/química
Escherichia coli/enzimologia
Proteínas de Membrana/química
Fenilalanina/química
-Motivos de Aminoácidos
Sequência de Aminoácidos
Proteínas de Bactérias/genética
Proteínas de Bactérias/metabolismo
Quimiotaxia
Sequência Conservada
Dimerização
Escherichia coli/química
Escherichia coli/genética
Escherichia coli/fisiologia
Dados de Sequência Molecular
Proteínas de Membrana/genética
Proteínas de Membrana/metabolismo
Conformação Proteica
Fenilalanina/genética
Fenilalanina/metabolismo
Tipo de Publ: Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
Responsável: BR1.1 - BIREME


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Id: lil-741526
Autor: Saffer, Fernanda; Lubianca, José Faibes Lubianca; Rösing, Cassiano; Dias, Caroline; Closs, Luciane.
Título: Predictors of Success in the Treatment of Obstructive Sleep Apnea Syndrome with Mandibular Repositioning Appliance: A Systematic Review
Fonte: Int. arch. otorhinolaryngol. (Impr.);19(1):80-85, Jan-Mar/2015. tab, graf.
Idioma: en.
Resumo: Introduction Obstructive sleep apnea syndrome affects up to 4% of middle-aged men and 2% of adult women. It is associated with obesity. Objective The objective of this article is to review the literature to determine which factors best correlate with treatment success in patients with obstructive sleep apnea syndrome treated with a mandibular repositioning appliance. Data Synthesis A search was performed of the PubMed, Cochrane, Lilacs, Scielo, and Web of Science databases of articles published from January 1988 to January 2012. Two review authors independently collected data and assessed trial quality. Sixty-nine articles were selected from PubMed and 1 from Cochrane library. Of these, 42 were excluded based on the title and abstract, and 27 were retrieved for complete reading. A total of 13 articles and 1 systematic review were considered eligible for further review and inclusion in this study: 6 studies evaluated anthropomorphic and physiologic factors, 3 articles addressed cephalometric and anatomic factors, and 4 studies evaluated variables related to mandibular repositioning appliance design and activation. All the studies evaluated had low to moderate methodologic quality and were not able to support evidence on prediction of treatment success. Conclusion Based on this systematic review on obstructive sleep apnea syndrome treatment, it remains unclear which predictive factors can be used with confidence to select patients suitable for treatment with a mandibular repositioning appliance. .
Descritores: Evolução Biológica
Proteínas de Transporte/química
Cinesina/química
Modelos Moleculares
Microtúbulos/metabolismo
-Transporte Biológico/fisiologia
Cercopithecus aethiops
Células COS
Dimerização
Transferência Ressonante de Energia de Fluorescência
Cinética
Microscopia de Fluorescência
Limites: Animais
Tipo de Publ: Research Support, N.I.H., Extramural
Responsável: BR1.1 - BIREME


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Id: lil-632391
Autor: Ariza, Ana Carolina; Bobadilla, Norma A.; Halhali, Ali.
Título: Acciones de endotelina 1 y angiotensina II en embarazos complicados con preeclampsia / Endothelin 1 and angiotensin II in preeeclampsia
Fonte: Rev. invest. clín;59(1):48-56, ene.-feb. 2007. ilus, tab.
Idioma: es.
Resumo: Introduction. It is generally thought that development of hypertension in preeclampsia (PE) is due to generalized endothelial dysfunction and/or results from an imbalance in the production and/or action of vasoactive factors, resulting in higher citosolic Ca2+ concentration which in turn leads to vasoconstriction and decreased blood pressure perfusion in organs, including the fetoplacental unit. Among vasoactive factors involved in blood pressure regulation, endothelin 1 (ET-1) and angiotensin II (Ang II) regulate citosolic Ca2+ concentrations and therefore are considered in this review. PE is associated with higher circulating and placental ET-1 levels, observation that explains, at least in part, vasoconstriction and oxidative stress. Higher and lower Ang II sensitivity seen in PE and normal pregnancy, respectively, could not be explained by changes in renin-angiotensin system components, including Ang II receptors (ATI). During normal pregnancy, ATI receptors are found as monomers and are inactivated by reactive oxygen species (ROS) leading to lower Ang II sensitivity. In contrast, PE is associated with increased ATl/bradicinin receptors (B2) heterodimers which are resistant to inactivation by ROS, maintaining increased ATI-receptor stimulated signaling in PE. In adittion, AT-1 agonistic antibodies (AT1-AA) obtained from PE women increases intracellular Ca2+, NADPH oxidase components and ROS, effects not observed with normal pregnancy AT1-AA. Conclusion. High ET-1 levels, the presence of AT1/B2 receptor heterodimers and increased AT1-AA are involved, at least in part, in the hypertensive and oxidative stress states in PE.

Introducción. Se reconoce que el desarrollo de la hipertensión en la preeclampsia (PE) resulta del daño endotelial generalizado y/o de la falta de equilibrio en la producción y/o acción de agentes vasoactivos, lo que conlleva al incremento en la concentración citosólica de Ca2+ que resulta en vasoconstricción y disminución de la perfusión sanguínea en los órganos, incluyendo la unidad fetoplacentaria. Dentro de los factores vaso-activos que regulan la presión arterial, en la presente revisión se consideró a la endotelina 1 (ET-1) y a la angiotensina II (Ang II), factores que regulan la concentración citosólica de Ca2+. En comparación con el embarazo normal, la PE se asocia con mayor concentración en suero y placenta de ET-1, lo que explica en parte la vasoconstricción y el estado de estrés oxidativo. La respuesta exagerada en la PE y el estado de refractariedad en el embarazo normal a la Ang II no pueden explicarse por componentes del sistema renina-angiotensina, incluyendo a los receptores de Ang II (ATI). Durante el embarazo normal los receptores AT-1 se encuentran en forma de monómeros y son inactivados por las especies reactivas de oxígeno (ROS), lo que se asocia con menor respuesta a Ang II. En cambio, la respuesta exagerada a la Ang II durante la PE puede deberse a la heterodimerizacion de los receptores ATI con los de bradicinina (B2), estado que les confiere resistencia a la inactivación por las especies reactivas de oxígeno (ROS), lo que explica el incremento en la concentración del Ca2+ intracelular. Además, los anticuerpos agonistas del receptor ATI (AT1-AA) de mujeres PE aumenta la concentración de Ca2+ intracelular, de la NADPH oxidasa y de ROS, efectos que no se presentan al utilizar AT1-AA de embarazadas normotensas. Conclusión. Las altas concentraciones de ET-1, la presencia de receptores ATI en forma de heterodimeros ATI/ B2 y el aumento en los AT1-AA explican en parte, el estado de hipertensión y de estrés oxidativo de la PE.
Descritores: Angiotensina II/fisiologia
Endotelina-1/fisiologia
Pré-Eclâmpsia/metabolismo
Receptor Tipo 1 de Angiotensina/fisiologia
/fisiologia
RECEPTOR, BRADYKININ BTEMEFOS/fisiologia
-Autoanticorpos/imunologia
Pressão Sanguínea/efeitos dos fármacos
Pressão Sanguínea/fisiologia
Sinalização do Cálcio
Dimerização
Endotelina-1/biossíntese
Troca Materno-Fetal
Modelos Biológicos
Óxido Nítrico/fisiologia
Estresse Oxidativo
Mapeamento de Interação de Proteínas
Pré-Eclâmpsia/fisiopatologia
Espécies Reativas de Oxigênio
Receptor Tipo 1 de Angiotensina/química
Receptor Tipo 1 de Angiotensina/imunologia
/química
RECEPTOR, BRADYKININ BTEMEFOS/química
Receptores de Endotelina/antagonistas & inibidores
Receptores de Endotelina/fisiologia
Sistema Renina-Angiotensina/fisiologia
Transdução de Sinais/fisiologia
Limites: Animais
Feminino
Seres Humanos
Gravidez
Ratos
Tipo de Publ: Research Support, Non-U.S. Gov't
Revisão
Responsável: MX1.1 - CENIDSP - Centro de Información para Decisiones en Salud Pública


  6 / 15 LILACS  
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Id: lil-593588
Autor: Medinas, Danilo Bilches.
Título: Atividade peroxidásica da enzima superóxido dismutase 1 humana: produção do radical carbonato, dimerização covalente da enzima e implicações para a esclerose lateral amiotrófica / Peroxidase activity of human superoxide dismutase 1: production of the carbonate radical, covalent dimerization of the enzyme, and implications to amyotrophic lateral sclerosis.
Fonte: São Paulo; s.n; 2010. 98 p. ilus, tab, graf.
Idioma: pt.
Tese: Apresentada a Universidade de São Paulo. Instituto de Química para obtenção do grau de Doutor.
Resumo: A esclerose lateral amiotrófica (ELA) é uma doença neurodegenerativa que afeta os neurônios motores levando a atrofia muscular e morte por insuficiência respiratória. Esta patologia se manifesta de forma esporádica ou familiar, que são indistinguíveis clinicamente. Mutações na enzima antioxidante superóxido dismutase 1 (hSod1) respondem por aproximadamente 20% dos casos familiares de ELA. Além disso, o caráter autossômico dominante destas mutações revela que a hSod1 adquire propriedades tóxicas aos neurônios motores. Atualmente, duas hipóteses não mutuamente excludentes existem para explicar o caráter tóxico das mutantes da hSod1 relacionadas à ELA. A primeira refere-se à produção de oxidantes pela atividade peroxidásica exacerbada das mutantes contribuindo para o estresse oxidativo observado em ELA. A segunda refere-se à agregação de proteínas como ocorre em outras doenças neurodegenerativas. Digno de nota, o radical carbonato produzido na atividade peroxidásica da hSod1 causa a formação de um dímero covalente da proteína análogo a uma espécie de hSod1 frequentemente detectada em modelos experimentais e pacientes da doença e associada à propriedade tóxica das mutantes. Desta forma, o presente trabalho buscou esclarecer o mecanismo de produção do radical carbonato pela hSod1, bem como caracterizar o dímero covalente da proteína para posterior estudo de sua formação em um modelo de ELA em ratos que superexpressam a mutante G93A da hSod1. Os estudos cinéticos da variação do pH sobre os efeitos de bicarbonato/CO2, nitrito e formato na atividade peroxidásica da hSod1, medidos pelo consumo de peróxido de hidrogênio e produção de radical, permitiram excluir o mecanismo de Fenton para explicar o ciclo peroxidativo da enzima em tampão bicarbonato em favor de outros intermediários reativos. Já, os experimentos de 13C RMN, modelagem molecular e cinética de fluxo interrompido com mistura assimétrica demonstraram que o ânion peroxomonocarbonato constitui o precursor...

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of motors neurons that causes muscle atrophy, weakness, and death by respiratory failure. This pathology occurs in both sporadic and familiar forms that are clinically indistinguishable. Mutations in the antioxidant enzyme superoxide dismutase 1 (hSod1) respond to about 20% of the familiar cases of ALS. Besides, the autosomal dominant nature of these hSod1-associated ALS suggests that the mutants gain toxic properties to motor neurons. Currently, two hypotheses exist to explain the toxicity of hSod1 mutants but they do not exclude each other. The first one is related to the production of oxidants by the increased peroxidase activity of the ALS-linked mutants that could contribute to the oxidative stress reported in ALS. The second refers to protein aggregation as proposed in other neurodegenerative diseases. Noteworthy, the carbonate radical produced during hSod1 peroxidase activity leads to the formation of a covalent dimer of the protein similar to a hSod1 species often detected in experimental models and patients of the disease and implicated in the toxic properties of hSod1 mutants. Thus, the present work aimed to determine the mechanism of carbonate radical production by hSod1 and to characterize the covalent dimer of the protein in vitro followed by the study of covalent aggregates of hSod1 in a rat model of ALS that overexpresses the G93A mutant of the protein. The kinetic studies of the effect of bicarbonate/CO2, nitrite and formate in the peroxidase activity of hSod1 at various pH, measured by hydrogen peroxide consumption and radical production, permitted to exclude the Fenton mechanism to explain the enzyme peroxidative cycle in bicarbonate buffer in favor of other reactive intermediates. Furthermore, 13C NMR, molecular docking and stopped-flow experiments with asymmetric mixing demonstrated that the anion peroxomonocarbonate is the precursor of the carbonate radical produced by...
Descritores: Dimerização
Ativação Enzimática
Enzimas
Esclerose Amiotrófica Lateral/fisiopatologia
Peroxidase
Superóxido Dismutase/química
-Radicais Livres
Biomarcadores/análise
Biomarcadores/química
Doenças Neurodegenerativas
Tipo de Publ: Estudos de Avaliação
Responsável: BR40.1 - DBD - Divisão de Biblioteca e Documentacão do Conjunto das Químicas
BR40.1; T574.192, M491a. 23612


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Id: lil-553764
Autor: Basso, T. S; Pungartnik, C; Brendel, M.
Título: Low productivity of ribonucleotide reductase in Saccharomyces cerevisiae increases sensitivity to stannous chloride
Fonte: Genet. mol. res. (Online);7(1):1-6, Jan. 2008. ilus.
Idioma: en.
Resumo: Ribonucleotide reductase (RNR) of the yeast Saccharomyces cerevisiae is a tetrameric protein complex, consisting of two large and two small subunits. The small subunits Y2 and Y4 form a heterodimer and are encoded by yeast genes RNR2 and RNR4, respectively. Loss of Y4 in yeast mutant rnr4delta can be compensated for by up-regulated expression of Y2, and the formation of a small subunit Y2Y2 homodimer that allows for a partially functional RNR. However, rnr4delta mutants exhibit slower growth than wild-type (WT) cells and are sensitive to many mutagens, amongst them UVC and photo-activated mono- and bi-functional psoralens. Cells of the haploid rnr4delta mutant also show a 3- to 4-fold higher sensitivity to the oxidative stress-inducing chemical stannous chloride than those of the isogenic WT. Both strains acquired increased resistance to SnCl2 with age of culture, i.e., 24-h cultures were more sensitive than cells grown for 2, 3, 4, and 5 days in liquid culture. However, the sensitivity factor of three to four (WT/mutant) did not change significantly. Cultures of the rnr4delta mutant in stationary phase of growth always showed higher frequency of budding cells (budding index around 0.5) than those of the corresponding WT (budding index <0.1), pointing to a delay of mitosis/cytokinesis.
Descritores: Compostos de Estanho/toxicidade
Genes Fúngicos/genética
Mutagênicos/toxicidade
Ribonucleotídeo Redutases/genética
Saccharomyces cerevisiae/enzimologia
-Sobrevivência Celular
Dimerização
Haploidia
Mutação
RNA Fúngico/biossíntese
Ribonucleotídeo Redutases/química
Saccharomycetales
Sensibilidade e Especificidade
Saccharomyces cerevisiae/citologia
Saccharomyces cerevisiae/genética
Fatores de Tempo
Responsável: BR26.1 - Biblioteca Central


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Texto completo SciELO Brasil
Costa, F. F
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Id: lil-550731
Autor: Souza, D. S; Spencer, D. M; Salles, T. S. I; Salomão, M. A; Payen, E; Beuzard, Y; Carvalho, H. F; Costa, F. F; Saad, S. T. Olalla.
Título: Death switch for gene therapy: application to erythropoietin transgene expression
Fonte: Braz. j. med. biol. res = Rev. bras. pesqui. méd. biol;43(7):634-644, July 2010. ilus, graf.
Idioma: en.
Resumo: The effectiveness of the caspase-9-based artificial "death switch" as a safety measure for gene therapy based on the erythropoietin (Epo) hormone was tested in vitro and in vivo using the chemical inducer of dimerization, AP20187. Plasmids encoding the dimeric murine Epo, the tetracycline-controlled transactivator and inducible caspase 9 (ptet-mEpoD, ptet-tTAk and pSH1/Sn-E-Fv'-Fvls-casp9-E, respectively) were used in this study. AP20187 induced apoptosis of iCasp9-modified C2C12 myoblasts. In vivo, two groups of male C57BI/6 mice, 8-12 weeks old, were injected intramuscularly with 5 µg/50 g ptet-mEpoD and 0.5 µg/50 g ptet-tTAk. There were 20 animals in group 1 and 36 animals in group 2. Animals from group 2 were also injected with the 6 µg/50 g iCasp9 plasmid. Seventy percent of the animals showed an increase in hematocrit of more than 65 percent for more than 15 weeks. AP20187 administration significantly reduced hematocrit and plasma Epo levels in 30 percent of the animals belonging to group 2. TUNEL-positive cells were detected in the muscle of at least 50 percent of the animals treated with AP20187. Doxycycline administration was efficient in controlling Epo secretion in both groups. We conclude that inducible caspase 9 did not interfere with gene transfer, gene expression or tetracycline control and may be used as a safety mechanism for gene therapy. However, more studies are necessary to improve the efficacy of this technique, for example, the use of lentivirus vector.
Descritores: Anemia/terapia
Caspase 9/genética
Dimerização
Eritropoetina
Expressão Gênica/genética
Terapia Genética/métodos
Tacrolimo/análogos & derivados
-Caspase 9/administração & dosagem
Eritropoetina
Vetores Genéticos/genética
Hematócrito
Injeções Intramusculares
Lentivirus/genética
MICE, INBRED CABDOMENABDOMINAL INJURIESBL
Plasmídeos/uso terapêutico
Tacrolimo/uso terapêutico
Limites: Animais
Masculino
Camundongos
Tipo de Publ: Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME


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Texto completo SciELO Brasil
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Id: lil-544615
Autor: Isea, Raúl; Ramírez, José Luis; Hoebeke, Johan.
Título: Assessing protein stability of the dimeric DNA-binding domain of E2 human papillomavirus 18 with molecular dynamics
Fonte: Mem. Inst. Oswaldo Cruz;105(2):123-126, Mar. 2010. ilus.
Idioma: en.
Resumo: The objective of this study is to understand the structural flexibility and curvature of the E2 protein of human papillomavirus type 18 using molecular dynamics (6 ns). E2 is required for viral DNA replication and its disruption could be an anti-viral strategy. E2 is a dimer, with each monomer folding into a stable open-faced â-sandwich. We calculated the mobility of the E2 dimer and found that it was asymmetric. These different mobilities of E2 monomers suggest that drugs or vaccines could be targeted to the interface between the two monomers.
Descritores: DNA Viral/genética
Proteínas de Ligação a DNA/genética
/genética
HUMAN PAPILLOMAVIRUS 1ABDOMINAL NEOPLASMS/genética
Proteínas Oncogênicas Virais/genética
-Dimerização
Replicação do DNA
DNA Viral/metabolismo
Proteínas de Ligação a DNA/metabolismo
/metabolismo
HUMAN PAPILLOMAVIRUS 1ABDOMINAL NEOPLASMS/metabolismo
Modelos Moleculares
Proteínas Oncogênicas Virais/metabolismo
Estabilidade Proteica
Replicação Viral
Responsável: BR1.1 - BIREME


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Texto completo SciELO Venezuela
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Id: lil-517093
Autor: Medina, Rafael; Moller, Carolina; Perdomo, Deisy; Bubis, José.
Título: Aproximaciones de bioquímica clásica al estudio de la relación entre la estructura y la función de la rodopsina Y / Approaches to the study of classical biochemistry of the relationship between structure and function of the rhodopsin
Fonte: Arch. venez. farmacol. ter;27(1):5-13, 2008. ilus.
Idioma: es.
Resumo: La proteína fotorreceptora rodopsina (R) fue extraída de los segmentos externos de los bastoncillos de retinas bovinas con el detergente n-dodecil β-D-maltósido (DM) y purificada a homogeneidad mediante cromatografía de afinidad. El entrecruzamiento químico de la R y de la rodopsina fotoactivada (R*) con los agentes bifuncionales sulfo-succinimidilo 4-(N-maleimidometilo) ciclohexano-1-carboxilato (sulfo-SMCC) o m-maleimidobenzoilo-N-hidroxisuccinimido ester, sugirieron la naturaleza oligomérica de la proteína fotorreceptora. La caracterización de los parámetros hidrodinámicos de la R y la R* en presencia de 0.1% DM, mediante cromatografía de exclusión molecular y sedimentación sobre gradientes de sacarosa, permitió estimar los tamaños de los complejos R:DM y R*: DM. Los resultados concuerdan con una estructura cuaternaria dimérica tanto para la R como para la R*. La R entrecruzada con sulfo-SMCC, en presencia de luz, fue estabilizada en un fotointermediario que absorbió a ~ 470 nm. Experimentos de proteólisis con termolísina sobre los dímeros nativos de R y sobre los monómeros de R generados por medio del uso de altas concentraciones de DM, complementados con estudios de modelaje basados en la estructura cristalina reportada de la proteína, sugirieron que el reactivo sulfo-SMCC generó un entrecruzamiento intramolecular entre la Cys140 y la Lys248 de la R, el cual posiblemente es el responsable de la incapacidad de la proteína de sufrir el cambio conformacional requerido para llegar a su estado fotoactivado.
Descritores: Dimerização
Hibridização Genética
Retina/química
Rodopsina/análise
Percepção Visual
-Reações Bioquímicas/métodos
Limites: Bovinos
Animais
Tipo de Publ: Estudos de Avaliação
Responsável: VE1.1 - Biblioteca Humberto Garcia Arocha



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