Objective: Heme oxygenase-1 (HO-1) has been well established as a cytoprotective molecule, and has been shown to exert cardioprotective effects in both hypertension and cardiac hypertrophy. However, the precise mechanism of the cardioprotective effect of HO-1 has yet to be fully elucidated. The natriuretic peptide system (NPS) is also a key player in cardiovascular homeostasis and tissue dynamics, and has also been shown to be cardioprotective in a variety of pathologic conditions. This study examined the effect of high dietary salt treatment in genetic models of HO-1, and assessed the expression of the NPS in the left ventricle (LV), in order to gain insight into the relationship between varying levels of HO-1 expression with the development of cardiac hypertrophy and the expression of the NPS. Methods: Age-matched 12-week old male HO-1 knockout (HO-1-/-) and HO-1 cardiomyocyte-specific transgenic overexpressing (HO-1Tg) mice were treated with either normal salt (NS; 0.8%) or high salt (HS; 8.0%) chow for 5 weeks. LV mRNA expression was determined using quantitative real-time RT-PCR. Results: HO-1-/- mice fed HS diet had significantly higher left ventricle-to-body weight ratio (LV/BW) compared to HO-1+/+ mice fed NS diet. HO-1-/- mice had significantly reduced expression of the NPS compared to controls, and these mice did not exhibit a salt-induced increase in ANP expression. HS treatment had no effect on LV/BW in HO-1Tg mice compared to controls. HO-1Tg mice had significantly higher ANP and BNP expression compared to controls. Conclusions: The presence of HO-1 is required for normal salt-induced changes in the local cardiac NPS. HO-1 ablation resulted in significantly lower mRNA expression of the NPS, whereas HO-1 overexpression resulted in higher mRNA expression of the NPS. These data indicate that the detrimental effect of reduced HO-1 expression and the cardioprotective effect of increased HO-1 expression may be due, in part, to altered expression of the NPS. / Thesis (Master, Anatomy & Cell Biology) -- Queen's University, 2009-10-20 09:15:20.541

In eukaryotic cells, energy is produced by the coordinated action of the mitochondrial respiratory chain (MRC) and the oxidative phosphorylation system (OXPHOS). Cytochrome c oxidase (COX) is the fourth enzyme of the MRC. COX catalytic activity is mediated by prosthetic groups located in subunits 1 (Cox1) and 2. More than twenty nuclear encoded factors are required for the assembly of the functional enzyme. Cox1 is the center of a regulatory mechanism in which its protein levels depend on the availability of its assembly partners. A key element in the regulatory pathway is the nuclear encoded factor Mss51, a protein essential for COX1 mRNA translation and Cox1 stability. In this thesis work, we show that Mss51 performs these two functions by dynamically interacting with several protein partners, including COX assembly chaperones and the Hsp70 general chaperone Ssc1. We have also characterized functional domains in Mss51. Specifically, we are reporting the presence of two conserved CPX (Val,Leu) heme-binding motifs, essential for in vivo Mss51 functions. Our data supports a system in which the efficiency of Mss51 as a translational activator is regulated by heme levels perhaps in a redox-sensitive manner. This study contributes to the current knowledge and understanding of the COX assembly process by disclosing new mechanisms involved in its intricate regulation.

Includes bibliography / 108 leaves, [24] leaves of plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1988

Bibliography : leaves 133-146. / 146, [41] leaves, [15] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1991

Bibliography : leaves 104-121. / 121, [57] leaves, [15] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1993?

Thesis (M.S.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Thesis advisor: Dr. William Durante. "December 2008" Includes bibliographical references.

This thesis is devoted to the evolution of the heme biosynthetic pathway in eukaryotic phototrophs with particular emphasis on algae possessing secondary and tertiary red and green derived plastids. Based on molecular biology and bioinformatics approaches it explores the diversity and similarities in heme biosynthesis among different algae. The core study of this thesis describes the heme biosynthesis in Bigelowiella natans and Guillardia theta, algae containing a remnant endosymbiont nucleus within their plastids, in dinoflagellates containing tertiary endosymbionts derived from diatoms called dinotoms, and in Lepidodinium chlorophorum, a dinoflagellate containing a secondary green plastid. The thesis further focusses on new insights in the heme biosynthetic pathway and general origin of the genes in chromerids the group of free-living algae closely related to apicomplexan parasites.

GUIMARÃES, Wellinson Gadêlha. FixL Híbrida da Bactéria Rhizobium etli: Estudos Conformacionais e de Estabilidade. 2016. 74 f. Dissertação (Mestrado em Química)-Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Weslayne Nunes de Sales (weslaynesales@ufc.br) on 2017-03-27T11:47:49Z No. of bitstreams: 1 2016_wgguimaraes.pdf: 2399264 bytes, checksum: 6b01ad2806daa748fbbbddeee1ed0c0d (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-03-27T22:56:19Z (GMT) No. of bitstreams: 1 2016_wgguimaraes.pdf: 2399264 bytes, checksum: 6b01ad2806daa748fbbbddeee1ed0c0d (MD5) / Made available in DSpace on 2017-03-27T22:56:19Z (GMT). No. of bitstreams: 1 2016_wgguimaraes.pdf: 2399264 bytes, checksum: 6b01ad2806daa748fbbbddeee1ed0c0d (MD5) Previous issue date: 2016 / Heme-based sensors are a class of hemeproteins that studies are relatively recent. Heme-based sensor are capable to reversibly bind to molecules such as O2, CO and NO ligands through iron atom, leading to conformational changes that govern adptative responses, make them actives or inactives to a response. FixL is a histidine kinase found in several bacteria Rhyzobium, being involved in microaerobic respiration and nitrogen metabolism processes. This protein has been extensively studied and is considered a model system to heme-based sensors that are histidine kinases. Its mechanisthic elucidation may help to understand many similar systems. In this work protein FixL from Rhyzobium etli, until now one only of genre that was studied, was produced and purified aiming to investigate conformational and stability aspects. Therefore, it was used Circular Dichroism (CD) to estimate the kind of secondary structure in FixL in a active state. It was revealed that it is majority organized on α-helices. After, it was investigated the possible conformational changes that FixL protein may have when its activity is changed due to be bounded to a signalizing ligand. Interesting results obtained suggest the potential use of CD technique and electronic spectroscopy to assess structural changes from an active state to inactive one that apparently occur by changing the tertiary structures. The results suggest that the heme interactions with nearby protein side chains are involved in loss of activity from FixL to bind O2 or CN-. Finally, stability studies by thermal and chemical denaturation showed that FixL is less stable than many other heme proteins, and that there are significant differences in stability between the active state and the inactive state, particularly with regard to chemical denaturation, although not had significant differences in the thermal stability. These differences in stability were explained in the light of a model in which the protein becomes more compact when it is enzymatically active by interaction inter / intra domains. / Heme proteínas sensoras (HPS) são uma classe de heme proteínas cujos estudos são relativamente recentes. As HPS são capazes de se ligar reversivelmente a moléculas como O2, CO e NO por meio do ferro do seu grupo heme, o que leva a alterações estruturais que governam as respostas adaptativas, tornando-as ativas ou inativas para uma resposta. A FixL é uma histidina quinase encontrada em várias bactérias do gênero Rhizobium, estando envolvida nos processos de respiração microaeróbica e no metabolismo do nitrogênio. Esta proteína tem sido bastante estudada, sendo considerada um sistema modelo para hemeproteínas sensoras que desempenham função histidina quinase, e cuja elucidação mecanística pode ajudar a entender diversos sistemas semelhantes. Neste trabalho foi produzida e purificada a proteína FixL da bactéria Rhyzobium etli, única do gênero estudada até agora, tendo como finalidade investigar aspectos conformacionais e de estabilidade. Desta forma, empregou-se espectroscopia de dicroísmo circular (CD) para estimar os tipos de estrutura secundária desta proteína em seu estado nativo, sendo revelado que sua estrutura se encontra majoritariamente na forma de α-hélices. Posteriormente, foram investigadas as possíveis alterações conformacionais que a proteína sofre por ocasião da mudança na sua atividade enzimática provocada por ligantes sinalizadores. Os interessantes resultados obtidos ilustram a potencialidade da técnica de CD e espectroscopia eletrônica em avaliar alterações estruturais de um estado ativo para inativo que ocorrem aparentemente através da mudança das estruturas terciárias. Os resultados sugerem que as interações do grupo heme com as cadeias protéicas laterais próximas estão envolvidas na perda de atividade da FixL ao se ligar ao O2 ou ao CN-. Por fim, os estudos de estabilidade por desnaturação térmica e química mostraram que a FixL é menos estável que diversas outras heme proteínas, e que existem diferenças significativas de estabilidade entre o estado ativo e o estado inativo, particularmente quanto à desnaturação química, apesar de não haverem diferenças significativas em relação à estabilidade térmica. Essas diferenças na estabilidade foram explicadas à luz de um modelo em que a proteína se torna mais compacta quanto está enzimaticamente ativa através de interações inter/intra domínios.

Made available in DSpace on 2016-05-19T13:20:08Z (GMT). No. of bitstreams: 2 cassia_shinotsuka_ipec_dout_2014.pdf: 2018653 bytes, checksum: 03fd6183adfbaa1b4e9703e2eba9f505 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2014 / Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil / Introdução: O acidente vascular encefálico hemorrágico e a hemorragia subaracnóide são doenças de elevada morbi-mortalidade. Os produtos da degradação da hemoglobina são implicados em diversos estudos experimentais como elementoschave na fisiopatologia da lesão secundária após a hemorragia intracraniana. Entretanto, há poucos dados em humanos que possam corroborar as observações experimentais. Objetivo: Avaliar o papel dos produtos da degradação da hemoglobina e dos mecanismos de proteção contra a hemoglobina e o heme na fisiopatologia do dano secundário à hemorragia intracraniana. Métodos: Estudo prospectivo realizado nas unidades neurointensivas de três hospitais. Foi coletado sangue e líquor (pela DVE) de pacientes internados com AVEh ou HSA e hemoventrículo durante os primeiros três dias após o ictus. Foram dosadas sequencialmente as concentrações de ferro, heme, hemopexina, haptoglobina, enolase e S100-\03B2 além de um painel de citocinas. O desfecho primário era mortalidade em 7 dias Resultados: Quinze pacientes foram incluídos, 10 com HSA e 5 com AVEh. Após a hemorragia intracraniana, ocorreu o desencadeamento da resposta inflamatória no sistema nervoso central (SNC), com níveis de IL-8 e GM-CSF no líquor cerca de 20x superiores ao do plasma. Foi observada a correlação entre a concentração de ferro e IP-10 no líquor (r=0,97; p=0,03) e heme e MIP-1b no líquor (r=0,76; p=0,01). Os níveis de hemopexina e haptoglobina foram consistentemente inferiores no líquor em relação ao plasma, ao longo dos três dias de estudo. Tanto o ferro e heme plasmáticos, quanto o grau de resposta inflamatória sistêmica e no SNC foram preditores de mortalidade nos primeiros 7 dias após o evento. Conclusão: Os resultados desse estudo mostram que tanto o ferro quanto o heme estão correlacionados ao desencadeamento da lesão secundária após a hemorragia intracraniana e estão associados ao pior prognóstico neste grupo de pacientes. Além disso, os mecanismos de proteção cerebral contra a hemoglobina e o heme são insuficientes. Mais estudos são necessários para elucidar o papel dos produtos da degradação da hemoglobina na fisiopatologia da hemorragia intracraniana em humanos / Introduction: Hemorrhagic stroke and subarachnoid hemorrhage are diseases with high morbidity and mortality. Hemoglobin degradation byproducts are being increasingly implicated in the pathophysiology of secondary brain injury after intracranial bleeding. However, there is not enough data in humans to support experimental evidence. Objective: To e valuate the role of hemoglobin degradat ion byproducts and protective mechanisms against hemoglobin and heme in the pathophysiology of secondary brain injury. Methods: Prospective study was done in three neurocritical care units. Blood and cerebrospinal fluid from EVD were collected from hemorrh agic stroke and su barachnoid hemorrhage patients throughout the first three days after the ictus. Sequentially measurement of iron, heme, haptoglobine, hemopexine, enolase, s100 - β and cytokines were performed. Primary outcome was 7 - day mortality. Results: Fifteen patients were included, 10 with subarachnoid hemorrhage and 5 with hemorrhagic stroke. After intracranial bleeding, local inflammatory response was elicited, with CSF IL - 8 and GM - CSF levels 20x higher than in plasma. There is a correlation between CSF iron and IP - 10 levels (r=0.97; p=0.03) and between CSF heme and MIP - 1b concentration (r=0.76; p=0.01). Throughout the first three days after the event, CSF hemopexine and haptog lobine concentrations we re consistently lower than in plasma. Both CSF iron and heme levels and systemic a nd local inflammatory response we re predictors of early mortality. Conclusion: The results of this study demonstrate that iron and heme are related to secondary brain injury after intracranial bleeding and are predictors of p oorer prognosis. Moreover, mechanisms of protection against hemoglobin and heme are lacking. More studies are needed to clarify the role of hemoglobin metabolism byproducts in the pathophysiology of intracranial bleeding in humans.

Orientador: Marcia M. C. Ferreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T03:09:25Z (GMT). No. of bitstreams: 1 Costa_MiriandaSilva_M.pdf: 2610467 bytes, checksum: f48f48cdaf34d2a003b2385139333a61 (MD5) Previous issue date: 2004 / Mestrado / Físico-Química / Mestre em Química