22 research outputs found
Mo and W bis-MGD enzymes: nitrate reductases and formate dehydrogenases
J Biol Inorg Chem (2004) 9: 791–799
DOI 10.1007/s00775-004-0573-9Molybdenum and tungsten are second- and third-row transition elements, respectively, which are found in a mononuclear form in the active site of a diverse group of enzymes that generally catalyze oxygen atom transfer reactions. Mononuclear Mo-containing enzymes have been classified into three families: xanthine oxidase, DMSO reductase, and sulfite oxidase. The proteins of the DMSO reductase family present the widest diversity of properties among its members and our knowledge about this family was greatly broadened by the study of the enzymes nitrate reductase and formate dehydrogenase, obtained from different sources. We discuss in this review the information of the better characterized examples of these two types of Mo enzymes and W enzymes closely related to the members of the DMSO reductase family. We briefly summarize, also, the few cases reported so far for enzymes that can function either with Mo or W at their active site
Anéis de Ferrara: - 4 Anos Depois
Os anéis intraestromais, nomeadamente o anel de Ferrara, constitui uma importante opção terapêutica das doenças ectásicas da córnea, de origem não inflamatória como o Queratocone. Os autores analisaram os primeiros 30 casos operados no Serviço de Oftalmologia do CHLC relativamente à eficácia, estabilidade e segurança deste procedimento ao longo dos 4 anos. Verificaram estabilidade refractiva, diminuição queratométrica e do equivalente esférico e boa tolerância ao material implantado. Os autores concluem que esta opção terapêutica para o queratocone é segura, reversÃvel, com resultados estáveis que permitem adiar ou evitar a queratoplastia
Avaliação do Conhecimento sobre a sua Doença em Doentes com Glaucoma seguidos na Consulta de Especialidade de um Hospital Central
Objectivo: Avaliar e comparar com a população geral o nÃvel de conhecimento sobre
a doença e o seu tratamento em doentes com glaucoma.
Doentes e Métodos: Noventa doentes com glaucoma e 90 doentes sem glaucoma foram entrevistados no departamento de glaucoma e de consulta geral do Centro Hospitalar de Lisboa Central. Foi solicitado o preenchimento de um questionário validado sobre a doença e o seu tratamento. Foram registados dados demográficos.
Resultados: Dezoito porcento e 51% dos doentes,respectivamente, com glaucoma e controlo, desconheciam a doença. Em 6 das 22 perguntas, mais de 50% dos doentes responderam acertadamente. Em 16 perguntas o número de respostas correctas dos doentes foi inferior a 50%. Os doentes com glaucoma têm um nÃvel de conhecimentos superior (p=7,9x10-6) ao grupo controlo. O nÃvel de conhecimento é maior quanto maior a duração da doença (p=0,03) e o nÃvel de escolaridade (p=0,0065).
Comentários: Os doentes com glaucoma têm um nÃvel de conhecimentos sobre a sua doença superior ao grupo controlo, não obstante ambos os grupos terem um conhecimento insuficiente. Devem ser tomadas medidas de prevenção primária e secundária, com recurso a material educacional, com o objectivo de melhorar os conhecimentos dos doentes e consequentemente a compliance
crystallization and structure determination using soft X-rays
Superoxide reductase is a 14 kDa metalloprotein containing a catalytic nonhaem
iron centre [Fe(His)4Cys]. It is involved in defence mechanisms against
oxygen toxicity, scavenging superoxide radicals from the cell. The oxidized form
of Treponema pallidum superoxide reductase was crystallized in the presence of
polyethylene glycol and magnesium chloride. Two crystal forms were obtained
depending on the oxidizing agents used after purification: crystals grown in the
presence of K3Fe(CN)6 belonged to space group P21 (unit-cell parameters
a = 60.3, b = 59.9, c = 64.8 A ° , = 106.9 ) and diffracted beyond 1.60 A ° resolution,
while crystals grown in the presence of Na2IrCl6 belonged to space group C2
(a = 119.4, b = 60.1, c = 65.6 A ° , = 104.9 ) and diffracted beyond 1.55 A ° . A
highly redundant X-ray diffraction data set from the C2 crystal form collected
on a copper rotating-anode generator ( = 1.542 A ° ) clearly defined the positions
of the four Fe atoms present in the asymmetric unit by SAD methods. A MAD
experiment at the iron absorption edge confirmed the positions of the previously
determined iron sites and provided better phases for model building and
refinement. Molecular replacement using the P21 data set was successful using a
preliminary trace as a search model. A similar arrangement of the four protein
molecules could be observed
Crystal structure of the zinc-, cobalt-, and iron-containing adenylate kinase from Desulfovibrio gigas: a novel metal-containing adenylate kinase from Gram-negative bacteria
J Biol Inorg Chem (2011) 16:51–61
DOI 10.1007/s00775-010-0700-8Adenylate kinases (AK) from Gram-negative bacteria are generally devoid of metal ions in their LID domain. However, three metal ions, zinc, cobalt, and iron, have been found in AK from Gram-negative bacteria. Crystal structures of substrate-free AK from Desulfovibrio gigas with three different metal ions (Zn2+, Zn-AK; Co2+, Co-AK; and Fe2+, Fe-AK) bound in its LID domain have been determined by X-ray crystallography to resolutions 1.8, 2.0, and 3.0 Ã…, respectively. The zinc and iron forms of the enzyme were crystallized in space group I222, whereas the cobalt-form crystals were C2. The presence of the metals was confirmed by calculation of anomalous difference maps and by X-ray fluorescence scans. The work presented here is the first report of a structure of a metal-containing AK from a Gram-negative bacterium. The native enzyme was crystallized, and only zinc was detected in the LID domain. Co-AK and Fe-AK were obtained by overexpressing the protein in Escherichia coli. Zn-AK and Fe-AK crystallized as monomers in the asymmetric unit, whereas Co-AK crystallized as a dimer. Nevertheless, all three crystal structures are very similar to each other, with the same LID domain topology, the only change being the presence of the different metal atoms. In the absence of any substrate, the LID domain of all holoforms of AK was present in a fully open conformational state. Normal mode analysis was performed to predict fluctuations of the LID domain along the catalytic pathway
Heterodimeric nitrate reductase (NapAB) from Cupriavidus necator H16: purification, crystallization and preliminary X-ray analysis
Acta Cryst. (2007). F63, 516–519The periplasmic nitrate reductase from Cupriavidus necator (also known as Ralstonia eutropha) is a heterodimer that is able to reduce nitrate to nitrite. It comprises a 91 kDa catalytic subunit (NapA) and a 17 kDa subunit (NapB) that is involved in electron transfer. The larger subunit contains a molybdenum active site with a bis-molybdopterin guanine dinucleotide cofactor as well as one [4Fe–4S] cluster, while the small subunit is a di-haem c-type cytochrome. Crystals of the oxidized form of this enzyme were obtained using polyethylene
glycol 3350 as precipitant. A single crystal grown at the High Throughput Crystallization Laboratory of the EMBL in Grenoble diffracted to beyond 1.5 A ° at the ESRF (ID14-1), which is the highest resolution reported to date for a nitrate reductase. The unit-cell parameters are a = 142.2, b = 82.4, c = 96.8 A ° , ß = 100.7°, space group C2, and one heterodimer is present per asymmetric unit
Cross-Cultural Validation of the Portuguese from Portugal Version of the Test for Respiratory and Asthma Control in Kids (TRACK) Questionnaire
Introduction. The Test for Respiratory and Asthma Control in Kids (TRACK) is a tool to assess asthma control in preschool children. This study aims to validate the Portuguese from Portugal version of the TRACK questionnaire. Methods. A prospective cohort study was carried out to assess their psychometric characteristics. Caregivers of 141 children under age 5 with asthma symptoms were enrolled. Results. Internal reliability was close to 0.70 (Cronbach's α). The test-retest reliability was 0.87. TRACK scores were different between well, partially, and non-controlled asthma groups (p less than 0.001). Patients rated as having better control showed an increase in TRACK scores. Conclusions. The Portuguese version of the TRACK questionnaire is accurate and reliable for monitoring asthma control. Its use may help to overcome challenges with the management of this age group.info:eu-repo/semantics/publishedVersio
Asthma App Use and Interest Among Patients With Asthma: A Multicenter Study
info:eu-repo/semantics/publishedVersio