Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
1.
Lett Appl Microbiol ; 67(3): 292-298, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29924392

RESUMO

This work aimed to investigate the prevalence of Staphylococcus in wild birds seized in illegal trade and their antimicrobial resistance patterns. Cloacal samples were obtained from 109 wild birds apprehended in the street markets in Rio de Janeiro, Brazil. Staphylococcus spp. were phenotypically and genotypically identified, and resistance profile was evaluated according to Clinical and Laboratory Standards Institute guidelines and by polymerase chain reaction of mecA and blaZ genes. Staphylococcus was detected in 45·9% (50/109) of the cloacal swab samples, and 39 (78·0%) isolates were resistant to one or more of the nine antimicrobials tested and were also positive to mecA (12/39) or blaZ genes (14/39). High percentage of resistance was detected to ampicillin, oxacillin, cefoxitin, clindamycin and tetracycline, with the absence of resistance to vancomycin. Wild birds captured and submitted to captive stress conditions of illegal trade market of Brazil may have an important role as reservoirs of Staphylococcus spp. and its antimicrobial resistance mechanisms. The significance of this study is revealed by the zoonotic and pathogenic potential of staphylococci and that impact to public health and requires monitoring polices of wild birds health in tropical areas. SIGNIFICANCE AND IMPACT OF THE STUDY: The isolation of Staphylococcus species that are not commonly isolated from wild bird faeces, the relatively high proportion of strains showing degrees of resistance to ß-lactamics, lincosamides and tetracycline, and also the presence of mecA and blaZ genes that has been associated with multidrug phenotype reveal its public health relevance and zoonotic potential. Consequently, this represents an important route to transmission of this pathogen and its antimicrobial resistance mechanisms throughout national and international frontiers fostered by the illegal trade of wild animals and close contact with humans.


Assuntos
Animais Selvagens/microbiologia , Aves/microbiologia , Staphylococcus/isolamento & purificação , Animais , Antibacterianos/farmacologia , Brasil/epidemiologia , Cefoxitina/farmacologia , Farmacorresistência Bacteriana , Humanos , Testes de Sensibilidade Microbiana , Oxacilina/farmacologia , Saúde Pública/economia , Staphylococcus/classificação , Staphylococcus/efeitos dos fármacos , Staphylococcus/genética
2.
Lupus ; 26(3): 294-298, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27681518

RESUMO

Background Estrogens have a modulatory effect on several immune responses, many of which are correlated to autoimmune diseases. Estrogens act through binding to their receptors, and an overexpression of these receptors has been identified in patients with different autoimmune diseases. Here we analyzed the association of a putative functional genetic variant in the main estrogen receptor (ERα) gene ( ESR1), and the susceptibility to clinical findings and severity of SLE. Methods A total of 426 individuals (266 healthy controls and 160 SLE patients) were genotyped for the polymorphism rs2234693 in the ESR1 gene. Allele and genotype frequencies were calculated and analyzed between cases and controls using Unphased software. Results The SNP rs2234693 was not associated with SLE per se but the minor allele rs2234693-C was correlated with the presence of nephritis and discoid skin rash. On the other hand, the rs2234693-CC genotype was correlated with the absence of arthritis as well as anti-ANA and anti-RNP autoantibodies. The comprehensive clinical analysis of these patients revealed a more severe status of the disease, characterized by a younger age of onset and higher number of organs involved when compared to European populations. Conclusions Minor allele rs2234693-C was associated with renal and cutaneous involvement, as well as the absence of arthritis, anti-ANA and anti-RNP autoantibodies.


Assuntos
Receptor alfa de Estrogênio/genética , Lúpus Eritematoso Sistêmico/genética , Adulto , Alelos , Anticorpos Antinucleares/genética , Artrite/genética , Brasil , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença , Humanos , Lúpus Eritematoso Sistêmico/imunologia , Masculino , Polimorfismo de Nucleotídeo Único , Adulto Jovem
3.
Biochim Biophys Acta ; 1837(7): 1148-64, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24662917

RESUMO

DsrC is a small protein present in organisms that dissimilate sulfur compounds, working as a physiological partner of the DsrAB sulfite reductase. DsrC contains two redox active cysteines in a flexible carboxy-terminal arm that are involved in the process of sulfite reduction or sulfur(1) compound oxidation in sulfur-reducing(2) or sulfur-oxidizing(3) organisms, respectively. In both processes, a disulfide formed between the two cysteines is believed to serve as the substrate of several proteins present in these organisms that are related to heterodisulfide reductases of methanogens. Here, we review the information on DsrC and its possible physiological partners, and discuss the idea that this protein may serve as a redox hub linking oxidation of several substrates to dissimilative sulfur metabolism. In addition, we analyze the distribution of proteins of the DsrC superfamily, including TusE that only requires the last Cys of the C-terminus for its role in the biosynthesis of 2-thiouridine, and a new protein that we name RspA (for regulatory sulfur-related protein) that is possibly involved in the regulation of gene expression and does not need the conserved Cys for its function. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.


Assuntos
Proteínas Arqueais/metabolismo , Proteínas de Bactérias/metabolismo , Sulfito de Hidrogênio Redutase/metabolismo , Enxofre/metabolismo , Sequência de Aminoácidos , Proteínas Arqueais/química , Proteínas Arqueais/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sulfito de Hidrogênio Redutase/química , Sulfito de Hidrogênio Redutase/genética , Dados de Sequência Molecular
4.
Clin Exp Rheumatol ; 30(3): 351-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22510473

RESUMO

OBJECTIVES: To analyse demographic and clinical variables in patients with disease onset before and after 40, 45 and 50 years in a large series of Brazilian SpA patients. METHODS: A common protocol of investigation was prospectively applied to 1424 SpA patients in 29 centres distributed through the main geographical regions in Brazil. The mean age at disease onset was 28.56 ± 12.34 years, with 259 patients (18.2%) referring disease onset after 40 years, 151 (10.6%) after 45 years and 81 (5.8%) after 50 years. Clinical and demographic variables and disease indices (BASDAI, BASFI, BASRI, MASES, ASQoL) were investigated. Ankylosing spondylitis was the most frequent disease (66.3%), followed by psoriatic arthritis (18%), undifferentiated SpA (6.7%), reactive arthritis (5.5%), and enteropathic arthritis (3.5%). RESULTS: Comparing the groups according to age of disease onset, those patients with later onset presented statistical association with female gender, peripheral arthritis, dactylitis, nail involvement and psoriasis, as well as negative statistical association with inflammatory low back pain, alternating buttock pain, radiographic sacroiliitis, hip involvement, positive familial history, HLA-B27 and uveitis. BASDAI, BASFI and quality of life, as well as physicians and patient's global assessment, were similar in all the groups. Radiographic indices showed worse results in the younger age groups. CONCLUSIONS: There are two different clinical patterns in SpA defined by age at disease onset: one with predominance of axial symptoms in the group with disease onset ≤ 40 years and another favouring the peripheral manifestations in those with later disease onset.


Assuntos
Índice de Gravidade de Doença , Espondilartrite/epidemiologia , Espondilartrite/fisiopatologia , Espondilite Anquilosante/epidemiologia , Espondilite Anquilosante/fisiopatologia , Adolescente , Adulto , Distribuição por Idade , Idade de Início , Idoso , Brasil/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
5.
Environ Microbiol ; 14(1): 101-13, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21651686

RESUMO

Desulfatibacillum alkenivorans AK-01 serves as a model organism for anaerobic alkane biodegradation because of its distinctive biochemistry and metabolic versatility. The D. alkenivorans genome provides a blueprint for understanding the genetic systems involved in alkane metabolism including substrate activation, CoA ligation, carbon-skeleton rearrangement and decarboxylation. Genomic analysis suggested a route to regenerate the fumarate needed for alkane activation via methylmalonyl-CoA and predicted the capability for syntrophic alkane metabolism, which was experimentally verified. Pathways involved in the oxidation of alkanes, alcohols, organic acids and n-saturated fatty acids coupled to sulfate reduction and the ability to grow chemolithoautotrophically were predicted. A complement of genes for motility and oxygen detoxification suggests that D. alkenivorans may be physiologically adapted to a wide range of environmental conditions. The D. alkenivorans genome serves as a platform for further study of anaerobic, hydrocarbon-oxidizing microorganisms and their roles in bioremediation, energy recovery and global carbon cycling.


Assuntos
Alcanos/metabolismo , Deltaproteobacteria/genética , Genoma Bacteriano , Ácidos/metabolismo , Álcoois/metabolismo , Anaerobiose , Biodegradação Ambiental , Crescimento Quimioautotrófico , DNA Bacteriano/genética , Deltaproteobacteria/metabolismo , Metaboloma , Anotação de Sequência Molecular , Oxirredução , Sulfatos/metabolismo
6.
J Dairy Sci ; 94(7): 3305-10, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21700015

RESUMO

Staphylococcus aureus produces exoproteins that contribute to its ability to colonize the mammary gland such as hemolysins, coagulase, slime, and protein A. This study characterized phenotypically and genotypically these virulence factors in 50 Staph. aureus isolates. These isolates were obtained from milk samples from subclinical mastitis cases identified in 15 dairy cattle farms located in the state of Rio de Janeiro, Brazil. All of the confirmed Staph. aureus samples were PCR positive for the coa gene, which displayed 3 different size polymorphisms. The amplification of the spaA X region yielded a single amplicon for each isolate with the prevalent amplicon sized 315 bp. The Staph. aureus isolates were 24 and 16% positive for the hla and hlb genes, respectively, and 22 and 20% positive for the icaA and icaD genes, respectively. Amplification of the agr gene RNAIII was positive in 74% of the strains. Twenty-seven different profiles were identified among the samples, indicating a great diversity of Staph. aureus involved in the etiology of mastitis cases in the analyzed region. These findings are valuable to the comprehension of the distribution of the profiles of Staph. aureus strains isolated from subclinical mastitis cases in the state of Rio de Janeiro.


Assuntos
Mastite Bovina/microbiologia , Infecções Estafilocócicas/veterinária , Staphylococcus aureus/patogenicidade , Fatores de Virulência/genética , Animais , Brasil , Bovinos , Feminino , Leite/microbiologia , Polimorfismo Genético/genética , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética
7.
Arq. bras. med. vet. zootec ; 63(3): 744-748, June 2011. tab
Artigo em Português | LILACS | ID: lil-595594

RESUMO

Staphylococcus aureus is the major pathogen causing intramammary infections in dairy cattle worldwide. Among the factors that contribute to its spread and infectious potential is the ability to overcome the mechanisms of antimicrobials activity. The present work investigated the antimicrobial resistance pattern and sensibility to bacteriocins produced by strains of Lactobacillus spp of 30 isolates of S. aureus from mastitis. From this, 29 are beta-lactamase producers. Eight isolates (26.6 percent) showed resistance to at least four antibiotics being considered multiresistent. All of them were mecA-positive. Otherwise, all isolates tested showed sensibility to at least one of the four bacteriocin producer strains. Due to the significant depletion of the efficacy of antimicrobials, pathogen growth inhibition by bacteriocins seems an alternative of biological control in infectious processes.


Assuntos
Animais , Bacteriocinas/análise , Lactobacillus , Mastite Bovina/diagnóstico , Staphylococcus aureus
9.
Osteoporos Int ; 21(9): 1617-9, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19936866

RESUMO

Zoledronic acid is effective for osteoporosis at a single annual intravenous dose. It usually causes few adverse effects; the most common are related to acute phase reactions. We reported the case of a 64-year-old woman who presented flare-up of hand osteoarthritis after zoledronic acid infusions. Despite the fact that arthralgia is a common side effect of intravenous bisphosphonates, development of inflammatory signs in osteoarthritic joints is a rare event. We hypothesized that this side effect is caused by a release of cytokines secondary to activation of gamma-delta T lymphocytes.


Assuntos
Conservadores da Densidade Óssea/efeitos adversos , Difosfonatos/efeitos adversos , Articulação da Mão , Imidazóis/efeitos adversos , Osteoartrite/induzido quimicamente , Feminino , Humanos , Pessoa de Meia-Idade , Osteoporose Pós-Menopausa/tratamento farmacológico , Ácido Zoledrônico
10.
Arq. bras. med. vet. zootec ; 61(3): 577-584, jun. 2009. ilus, graf, tab
Artigo em Português | LILACS | ID: lil-519449

RESUMO

Avaliou-se o perfil de suscetibilidade bacteriana de diferentes sítios infecciosos frente aos antimicrobianos de eleição e determinaram-se o perfil de atividade in vitro e a concentração inibitória mínima (CIM) da azitromicina. Diferentes testes fenotípicos detectaram resistência à azitromicina em 45 por cento de Staphylococcus spp. e 65 por cento dos bastonetes Gram-negativo. A CIM50 para S. aureus foi 4,0μg/mL para S. intermedius 1,0μg/mL, Staphylococcus spp. coagulase-negativo >512μg/mL e bastonetes Gram-negativo 256μg/mL. Investigou-se, também, uma possível resistência cruzada entre oxacilina e azitromicina por meio da detecção do gene mecA em Staphylococcus spp. Foi possível detectar resistência à azitromicina em nove (15 por cento) isolados de Staphylococcus spp. mecA positivo.


Antimicrobials susceptibility pattern of bacterial isolated from different sites of infection, in vitro azithromycin activity pattern, and its minimum inhibitory concentration (MIC) values were evaluated. Different phenotypic tests detected azithromycin resistance in 45 percent of Staphylococcus spp. and 65 percent of resistant Gram-negative rods. MIC50 was 4.0μg/mL for Staphylococcus aureus, 1.0μg/mL for S. intermedius, >512.0μg/mL for coagulase negative Staphylococcus, and 256.0μg/mL for Gram-negative rods. In addition, it was investigated the possible cross-resistance between oxacillin and azithromycin, by detection of mecA gen in Staphylococcus spp. Nine (15 percent) mecA-positive Staphylococcus spp. were also phenotypically resistant to azithromycin.


Assuntos
Animais Domésticos , Antibacterianos , Azitromicina/efeitos adversos , Resistência a Medicamentos
11.
Ann Rheum Dis ; 68(7): 1086-93, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19033291

RESUMO

OBJECTIVES: To develop evidence-based recommendations for the use of methotrexate in daily clinical practice in rheumatic disorders. METHODS: 751 rheumatologists from 17 countries participated in the 3E (Evidence, Expertise, Exchange) Initiative of 2007-8 consisting of three separate rounds of discussions and Delphi votes. Ten clinical questions concerning the use of methotrexate in rheumatic disorders were formulated. A systematic literature search in Medline, Embase, Cochrane Library and 2005-7 American College of Rheumatology/European League Against Rheumatism meeting abstracts was conducted. Selected articles were systematically reviewed and the evidence was appraised according to the Oxford levels of evidence. Each country elaborated a set of national recommendations. Finally, multinational recommendations were formulated and agreement among the participants and the potential impact on their clinical practice was assessed. RESULTS: A total of 16 979 references was identified, of which 304 articles were included in the systematic reviews. Ten multinational key recommendations on the use of methotrexate were formulated. Nine recommendations were specific for rheumatoid arthritis (RA), including the work-up before initiating methotrexate, optimal dosage and route, use of folic acid, monitoring, management of hepatotoxicity, long-term safety, mono versus combination therapy and management in the perioperative period and before/during pregnancy. One recommendation concerned methotrexate as a steroid-sparing agent in other rheumatic diseases. CONCLUSIONS: Ten recommendations for the use of methotrexate in daily clinical practice focussed on RA were developed, which are evidence based and supported by a large panel of rheumatologists, enhancing their validity and practical use.


Assuntos
Antirreumáticos/administração & dosagem , Metotrexato/administração & dosagem , Doenças Reumáticas/tratamento farmacológico , Anormalidades Induzidas por Medicamentos/etiologia , Administração Oral , Antirreumáticos/efeitos adversos , Quimioterapia Combinada , Medicina Baseada em Evidências , Feminino , Ácido Fólico/administração & dosagem , Humanos , Assistência de Longa Duração , Masculino , Metotrexato/efeitos adversos , Cuidado Pré-Concepcional , Fatores de Risco
12.
Artigo em Inglês | MEDLINE | ID: mdl-16754983

RESUMO

The cytochrome c nitrite reductase (cNiR) isolated from Desulfovibrio vulgaris Hildenborough is a membrane-bound complex formed of NrfA and NrfH subunits. The catalytic subunit NrfA is a soluble pentahaem cytochrome c that forms a physiological dimer of about 120 kDa. The electron-donor subunit NrfH is a membrane-anchored tetrahaem cytochrome c of about 18 kDa molecular weight and belongs to the NapC/NirT family of quinol dehydrogenases, for which no structures are known. Crystals of the native cNiR membrane complex, solubilized with dodecylmaltoside detergent (DDM), were obtained using PEG 4K as precipitant. Anomalous diffraction data were measured at the Swiss Light Source to 2.3 A resolution. Crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 79.5, b = 256.7, c = 578.2 A. Molecular-replacement and MAD methods were combined to solve the structure. The data presented reveal that D. vulgaris cNiR contains one NrfH subunit per NrfA dimer.


Assuntos
Citocromos a1/química , Citocromos c1/química , Desulfovibrio vulgaris/enzimologia , Proteínas de Membrana/química , Nitrato Redutases/química , Membrana Celular/química , Cristalização/métodos , Subunidades Proteicas/química , Difração de Raios X
15.
Chembiochem ; 2(12): 895-905, 2001 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-11948878

RESUMO

A new tetraheme cytochrome c3 was isolated from the membranes of Desulfovibrio vulgaris Hildenborough (DvH). This cytochrome has a molecular mass of 13.4 kDa and a pI of 5.5 and contains four heme c groups with apparent reduction potentials of -170 mV, -235 mV, -260 mV and -325 mV at pH 7.6. The complete sequence of the new cytochrome, retrieved from the preliminary data of the DvH genome, shows that this cytochrome is homologous to the "acidic" cytochrome c3 from Desulfovibrio africanus (Da). A model for the structure of the DvH cytochrome was built based on the structure of the Da cytochrome. Both cytochromes share structural features that distinguish them from other cytochrome c3 proteins, such as a solvent-exposed heme 1 surrounded by an acidic surface area, and a heme 4 which lacks most of the surface lysine patch proposed to be the site of hydrogenase interaction in other cytochrome c3 proteins. Furthermore, in contrast to previously discovered cytochrome c3 proteins, the genes coding for these two cytochromes are adjacent to genes coding for two membrane-associated FeS proteins, which indicates that they may be part of membrane-bound oxidoreductase complexes. Altogether these observations suggest that the DvH and Da cytochromes are a new type of cytochrome c3 proteins (Type II: TpII-c3) with different redox partners and physiological function than the other cytochrome c3 proteins (Type I: TpI-c3). The DvH TpII-c3 is reduced at considerable rates by the two membrane-bound [NiFe] and [NiFeSe] hydrogenases, but catalytic amounts of TpI-c3 increase these rates two- and fourfold, respectively. With the periplasmic [Fe] hydrogenase TpII-c3 is reduced much slower than TpI-c3, and no catalytic effect of TpI-c3 is observed.


Assuntos
Grupo dos Citocromos c/química , Desulfovibrio vulgaris/química , Sequência de Aminoácidos , Cromatografia em Agarose , Cromatografia DEAE-Celulose , Cromatografia Líquida de Alta Pressão , Grupo dos Citocromos c/genética , Grupo dos Citocromos c/isolamento & purificação , Desulfovibrio vulgaris/genética , Ponto Isoelétrico , Modelos Moleculares , Dados de Sequência Molecular , Peso Molecular , Oxirredução , Conformação Proteica , Homologia de Sequência de Aminoácidos , Espectrofotometria Ultravioleta
16.
Biochim Biophys Acta ; 1481(1): 119-30, 2000 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-11004582

RESUMO

A cytochrome c nitrite reductase (NiR) was purified for the first time from a microorganism not capable of growing on nitrate, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough. It was isolated from the membranes as a large heterooligomeric complex of 760 kDa, containing two cytochrome c subunits of 56 and 18 kDa. This complex has nitrite and sulfite reductase activities of 685 micromol NH(4)(+)/min/mg and 1.0 micromol H(2)/min/mg. The enzyme was studied by UV-visible and electron paramagnetic resonance (EPR) spectroscopies. The overall redox behavior was determined through a visible redox titration. The data were analyzed with a set of four redox transitions, with an E(0)' of +160 mV (12% of total absorption), -5 mV (38% of total absorption), -110 mV (38% of total absorption) and -210 mV (12% of total absorption) at pH 7.6. The EPR spectra of oxidized and partially reduced NiR show a complex pattern, indicative of multiple heme-heme magnetic interactions. It was found that D. vulgaris Hildenborough is not capable of using nitrite as a terminal electron acceptor. These results indicate that in this organism the NiR is not involved in the dissimilative reduction of nitrite, as is the case with the other similar enzymes isolated so far. The possible role of this enzyme in the detoxification of nitrite and/or in the reduction of sulfite is discussed.


Assuntos
Grupo dos Citocromos c/química , Desulfovibrio vulgaris/enzimologia , Nitrito Redutases/química , Sequência de Aminoácidos , Ácido Ascórbico , Grupo dos Citocromos c/isolamento & purificação , Desulfovibrio vulgaris/crescimento & desenvolvimento , Espectroscopia de Ressonância de Spin Eletrônica , Eletroforese em Gel de Poliacrilamida , Dados de Sequência Molecular , Oxirredução , Cianeto de Sódio , Espectrofotometria
17.
J Clin Microbiol ; 38(2): 931-4, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10655421

RESUMO

Eight isolates of Desulfovibrio spp. have been obtained over 5 years from abdominal or brain abscesses or blood. Seven isolates were part of a mixed flora [corrected]. One strain was isolated in pure culture from the blood of a patient with peritonitis of appendicular origin. According to the 16S rRNA gene sequences, this strain was close to Desulfovibrio fairfieldensis. The present report describes the fourth isolate of this recently described species to be isolated in pure culture or as a predominant part of the flora and to be associated with infectious processes. Thus, D. fairfieldensis may possess a higher pathogenic potential than other Desulfovibrio species.


Assuntos
Bacteriemia/microbiologia , Desulfovibrio/classificação , Desulfovibrio/isolamento & purificação , Infecções por Bactérias Gram-Negativas/microbiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Pré-Escolar , DNA Bacteriano/genética , DNA Ribossômico/genética , Desulfovibrio/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Peritonite/microbiologia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
18.
Structure ; 7(2): 119-30, 1999 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-10368280

RESUMO

BACKGROUND: Haem-containing proteins are directly involved in electron transfer as well as in enzymatic functions. The nine-haem cytochrome c (9Hcc), previously described as having 12 haem groups, was isolated from cells of Desulfovibrio desulfuricans ATCC 27774, grown under both nitrate- and sulphate-respiring conditions. RESULTS: Models for the primary and three-dimensional structures of this cytochrome, containing 292 amino acid residues and nine haem groups, were derived using the multiple wavelength anomalous dispersion phasing method and refined using 1.8 A diffraction data to an R value of 17.0%. The nine haem groups are arranged into two tetrahaem clusters, with Fe-Fe distances and local protein fold similar to tetrahaem cytochromes c3, while the extra haem is located asymmetrically between the two clusters. CONCLUSIONS: This is the first known three-dimensional structure in which multiple copies of a tetrahaem cytochrome c3-like fold are present in the same polypeptide chain. Sequence homology was found between this cytochrome and the C-terminal region (residues 229-514) of the high molecular weight cytochrome c from Desulfovibrio vulgaris Hildenborough (DvH Hmc). A new haem arrangement in domains III and IV of DvH Hmc is proposed. Kinetic experiments showed that 9Hcc can be reduced by the [NiFe] hydrogenase from D. desulfuricans ATCC 27774, but that this reduction is faster in the presence of tetrahaem cytochrome c3. As Hmc has never been found in D. desulfuricans ATCC 27774, we propose that 9Hcc replaces it in this organism and is therefore probably involved in electron transfer across the membrane.


Assuntos
Grupo dos Citocromos c/química , Desulfovibrio/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Cristalografia por Raios X , Transporte de Elétrons , Heme/química , Hemeproteínas/química , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos
19.
Rev. Assoc. Med. Bras. (1992) ; 43(4): 311-3, out.-dez. 1997.
Artigo em Português | LILACS | ID: lil-208751

RESUMO

A síndrome vasculite urticariforme hipocomplementêmica é uma vasculite leucocitoclástica que se apresenta com lesöes urticariformes, associada a febre, artralgias, artrite e cólica abdominal. Outras manifestaçöes sistêmicas incluem a presença de glomerulonefrite, uveíte, episclerite, doença pulmonar obstrutiva e alteraçöes neurológicas. Alguns casos associados ao lúpus eritematoso sistêmico (LES) têm sido descritos, com o diagnóstico baseando-se na presença de critérios bem definidos de LES prévia ou concomitantemente ao aparecimento de vasculite urticariforme. A apresentaçäo de vasculite urticariforme precedendo o diagnóstico de LES é rara, o que motivou o relato destes dois casos. Enfatiza-se a positivaçäo do anticorpo anti-Ro/SS-A por ocasiäo do diagnóstico de LES, alertando para a necessidade de avaliaçäo periódica nos casos de vasculite urticariforme.


Assuntos
Adulto , Humanos , Feminino , Lúpus Eritematoso Sistêmico/complicações , Urticária/complicações , Vasculite Leucocitoclástica Cutânea/complicações , Lúpus Eritematoso Sistêmico/sangue , Síndrome , Urticária/sangue , Vasculite Leucocitoclástica Cutânea/sangue
20.
Eur J Biochem ; 248(2): 323-8, 1997 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-9346284

RESUMO

Two new multiheme cytochromes were isolated from the anaerobic sulfur reducing bacterium Desulfuromonas acetoxidans. They have monomeric molecular masses of 50 and 65 kDa and contain six and eight hemes, respectively. Visible and EPR spectroscopies, in the as-isolated (oxidised) cytochromes, show the presence of only low-spin hemes in the 50-kDa cytochrome, and of high-spin and low-spin hemes in the 65-kDa cytochrome. The EPR spectra of the native 65-kDa cytochrome indicate multiple heme-heme interactions, including integer-spin systems as judged by parallel-mode EPR. The 50-kDa cytochrome has a complex redox pattern, as shown by EPR redox titrations, and contains one heme with unusual characteristics. Both cytochromes cover an extremely wide range of reduction potentials, which go from +100 mV to -375 mV for the 50-kDa cytochrome, and +185 mV to -235 mV for the 65-kDa cytochrome. The two cytochromes were tested for hydroxylamine oxidoreductase activity and polysulfide reductase activity, but neither displayed any activity. In contrast, it was found for the first time that the previously characterised cytochrome c551.5, from the same bacterium is very active in the reduction of polysulfide, which suggests that it acts as a terminal reductase in D. acetoxidans.


Assuntos
Citocromos/química , Citocromos/metabolismo , Bactérias Redutoras de Enxofre/enzimologia , Sequência de Aminoácidos , Espectroscopia de Ressonância de Spin Eletrônica , Dados de Sequência Molecular , Oxirredução , Espectrofotometria
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...