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This study was performed to examine whether capsaicin, the main pungent ingredient of red peppers, exerts protective effects against testicular injuries induced by transient scrotal hyperthermia. Capsaicin (0.33 mg kg-1 ) was administered subcutaneously to mice one hour before heat stress (HS) in a 43°C water bath for 20 min. After 7 days, mice exposed to HS showed low testicular weight, severe vacuolisation of seminiferous tubules followed by loss of spermatogenic cells, and appearance of multinucleated giant cells and remarkable TUNEL-positive apoptotic cells, as well as weak immunoreactivity of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in spermatogenic cells. Levels of lipid peroxidation and heat shock 70-kDa protein 1 (Hsp72) and BCL2-associated X protein (Bax) mRNA were greatly increased, but PHGPx, manganese superoxide dismutase (MnSOD), and B-cell lymphoma-extra large (Bcl-xL) mRNAs were significantly diminished in the testes by HS. However, capsaicin pre-treatment significantly suppressed the spermatogenic cell death, oxidative stress (levels of MDA, PHGPx immunoreactivity, and Hsp72, PHGPx, and MnSOD mRNA) and apoptosis (levels of TUNEL-positive cells, and Bcl-xL and Bax mRNA) in testes by HS. These suggest that capsaicin has a protective effect against spermatogenic cell death induced by scrotal hyperthermia through its antioxidative and anti-apoptotic activities.
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Apoptose/efeitos dos fármacos , Capsaicina/administração & dosagem , Temperatura Alta , Escroto/fisiologia , Espermatogênese/fisiologia , Animais , Antioxidantes , Glutationa Peroxidase/análise , Glutationa Peroxidase/genética , Proteínas de Choque Térmico HSP72/genética , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , RNA Mensageiro/análise , Espermatogênese/efeitos dos fármacos , Espermatozoides/citologia , Espermatozoides/enzimologia , Espermatozoides/fisiologia , Superóxido Dismutase/genética , Testículo/química , Testículo/citologia , Testículo/fisiologia , Proteína X Associada a bcl-2/genéticaAssuntos
COVID-19/complicações , Mortalidade Hospitalar , Procedimentos Cirúrgicos Operatórios/mortalidade , Adulto , Idoso , COVID-19/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2 , Estados Unidos/epidemiologiaRESUMO
Introduction: CTCF-related disorder (CRD) is a neurodevelopmental disorder (NDD) caused by monoallelic pathogenic variants in CTCF. The first CTCF variants in CRD cases were documented in 2013. To date, 76 CTCF variants have been further described in the literature. In recent years, due to the increased application of next-generation sequencing (NGS), growing numbers of CTCF variants are being identified, and multiple genotype-phenotype databases cataloging such variants are emerging. Methods: In this study, we aimed to expand the genotypic spectrum of CRD, by cataloging NDD phenotypes associated with reported CTCF variants. Here, we systematically reviewed all known CTCF variants reported in case studies and large-scale exome sequencing cohorts. We also conducted a meta-analysis using public variant data from genotype-phenotype databases to identify additional CTCF variants, which we then curated and annotated. Results: From this combined approach, we report an additional 86 CTCF variants associated with NDD phenotypes that have not yet been described in the literature. Furthermore, we describe and explain inconsistencies in the quality of reported variants, which impairs the reuse of data for research of NDDs and other pathologies. Discussion: From this integrated analysis, we provide a comprehensive and annotated catalog of all currently known CTCF mutations associated with NDD phenotypes, to aid diagnostic applications, as well as translational and basic research.
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OBJECTIVES: To construct three-dimensional (3D) horizontal reference planes based on visual pathway and to determine their stability and reliability by analyzing the structural patterns of normal and dysmorphology for 3D craniofacial analysis. SETTING AND SAMPLE POPULATION: Thirty-six subjects with maxillofacial dysmorphology and malocclusion, and eight normal controls. MATERIALS AND METHODS POPULATION: On the 3D computed tomographic images of the subjects, the visual pathway-based planes, including the orbital axis plane (OAP), visual axis plane (VAP), and the optical axis plane (OpAP), were constructed and evaluated. RESULTS: The OAP, but not the VAP and OpAP, showed the ideal relationship between the midsagittal and posterior maxillary plane, and properly described the different patterns of maxillofacial dysmorphology with craniofacial plane 1 of Delaire's analysis and the occlusal plane. CONCLUSIONS: The proposed visual pathway-related horizontal reference planes, and in particular the OAP, seem to correctly express the visual axis and the position of the head in natural head position and can be used as a horizontal reference plane for the 3D analysis of craniofacial dysmorphology and anthropology.
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Cefalometria/métodos , Anormalidades Craniofaciais/diagnóstico , Imageamento Tridimensional/métodos , Órbita/anatomia & histologia , Vias Visuais/anatomia & histologia , Vias Visuais/diagnóstico por imagem , Estudos de Casos e Controles , Cefalometria/normas , Face/anatomia & histologia , Cabeça , Humanos , Postura , Padrões de Referência , Reprodutibilidade dos Testes , Tomografia Computadorizada por Raios XRESUMO
Air pollution has significant health effects worldwide, and airborne particles play a significant role in these effects. Ultrafine particles (UFPs) have an aerodynamic diameter of 0.1 µm or less, can penetrate deep into the respiratory tree, and are more toxic due to their large specific surface area, which should adsorb organic compounds. The aim of this study is to show the toxicological effects of UFPs with high organic content at low dose on BEAS-2B cells through at air-liquid interface (ALI) exposure using a Vitrocell® technology and a miniCAST (Combustion Aerosol Standard) generator. In conjunction with this approach, chemical analysis of particles and gas phase was performed to evaluate the presence of polycyclic aromatic hydrocarbons (PAHs). Chemical analyses confirmed the presence of PAHs in UFPs. With this experimental setup, exposure of the BEAS-2B cells induced neither cytotoxicity nor mitochondrial dysfunction. However, an increase of oxidative stress was observed, as assessed through Nrf2, NQO1, HO-1, CuZnSOD, MnSOD, and Catalase gene expression, together with significant induction of genes related to xenobiotic metabolism CYP1A1 and CYP1B1. Negative regulation of inflammatory genes expression (IL-6 and IL-8) was present three hours after the exposition to the UFPs. Taken together, this experimental approach, using repeatable conditions, should help to clarify the mechanisms by which organic UFPs induce toxicological effects.
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Material Particulado/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/análise , Fuligem/toxicidade , Linhagem Celular , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP1B1/genética , Citocromo P-450 CYP1B1/metabolismo , Humanos , Interleucinas/genética , Interleucinas/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Material Particulado/química , Fuligem/químicaRESUMO
The application of Monte Carlo methods to simulate the agglomeration of suspended nanoparticles is currently limited to specific agglomeration regimes with reduced accuracy in terms of the particle's physical residence time. The definition of specific particles persistent distance, its corresponding time step and subsequent probabilities for particle displacements may improve the accuracy of this method. To solve these issues, a new persistent distance and its corresponding time step based on Langevin dynamics simulations are introduced. Additionally, a probability of particle displacements, not restricted to a specific agglomeration regime, is introduced. All the modifications are validated by comparison with Langevin dynamics simulations. Finally, the above mentioned modifications considerably improve the accuracy of Monte Carlo methods to predict the dynamics and agglomeration of suspended nanoparticles.
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During the agglomeration of nanoparticles and in particular, soot, a change in both the flow regime (from free molecular to near continuum) as well as the change of agglomeration regime (from ballistic to diffusive) is expected. However, these effects are rarely taken into account in numerical simulations of particle agglomeration and yet, they are suspected to have an important impact on the agglomeration kinetics, particle morphologies, and size distributions. This work intends to study these properties by using the Monte Carlo Aggregation Code (MCAC) presented in the preceding work (part 1), focusing on the physical impacts of varying the particle volume fraction and monomers size and polydispersity. The results show an important sensitivity of the kinetics of agglomeration, coagulation homogeneity, and agglomerate morphology to the size of monomers. First, for smaller monomer diameters, the agglomeration kinetic is enhanced and agglomerates are characterized by larger fractal dimensions. Second, for large monomer diameters, fractal dimensions down to 1.67 can be found being smaller than the classical 1.78 for Diffusion Limited Cluster Agglomeration (DLCA) mechanism. One important conclusion is that variation in time of both regimes has to be considered for a more accurate simulation of the agglomerate size distribution and morphology.
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Frequent exposure of children to general anesthesia is common practice in modern medicine. Although previously unrecognized, recent in vitro and in vivo animal studies suggest that exposure to clinically relevant general anesthetics at the peak of brain development could be detrimental to immature mammalian neurons, as demonstrated by massive and widespread apoptotic neurodegeneration. The survival of the developing neurons presumably depends on proper and timely formation of synapses, for which synaptic proteins (e.g., synaptophysin, synaptobrevin, amphiphysin, synaptosomal-associated protein 25 [SNAP-25], and Ca(2+)/calmodulin-dependent protein kinase II [CaM kinase II]) are crucially important. Overinhibition of developing neurons impairs synaptic protein function and activity-induced synaptic plasticity, which could in turn result in permanent neuronal loss. To examine the effects of general anesthesia, the pharmacological agents known to cause extensive neuronal inhibition, on synaptic proteins, and neuronal survival at the peak of synaptogenesis, we exposed 7-day-old rat pups to general anesthesia (midazolam, 9 mg/kg of body weight, subcutaneously, followed by 6 h of nitrous oxide 75 vol% and isoflurane 0.75 vol%). We found that this general anesthesia causes permanent neuronal deletion in the most vulnerable brain regions-the cerebral cortex and the thalamus-while transiently modulating protein levels of synaptophysin, synaptobrevin, amphiphysin, SNAP-25, and CaM kinase II.
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Anestésicos Inalatórios/efeitos adversos , Apoptose/efeitos dos fármacos , Encéfalo/citologia , Encéfalo/crescimento & desenvolvimento , Neurônios/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Proteínas do Tecido Nervoso/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores de TempoRESUMO
The mouse Surfeit locus, which contains a cluster of at least four genes (Surf-1 to Surf-4), is unusual in that adjacent genes are separated by no more than 73 base pairs (bp). The heterogeneous 5' ends of Surf-1 and Surf-2 are separated by only 15 to 73 bp, the 3' ends of Surf-1 and Surf-3 are only 70 bp apart, and the 3' ends of Surf-2 and Surf-4 overlap by 133 bp. This very tight clustering suggests a cis interaction between adjacent Surfeit genes. The Surf-3 gene (which could code for a basic polypeptide of 266 amino acids) is a highly expressed member of a pseudogene-containing multigene family. By use of an anti-peptide serum (against the C-terminal nine amino acids of the putative Surf-3 protein) for immunofluorescence and immunoblotting of mouse cell components and by in vitro translation of Surf-3 cDNA hybrid-selected mRNA, the Surf-3 gene product was identified as a 32-kilodalton ribosomal protein located in the 60S ribosomal subunit. From its subunit location, gel migration, and homology with a limited rat ribosomal peptide sequence, the Surf-3 gene was shown to encode the mouse L7a ribosomal protein. The Surf-3 gene is highly conserved through evolution and was detected by nucleic acid hybridization as existing in multiple copies (multigene families) in other mammals and as one or a few copies in birds, Xenopus, Drosophila, and Schizosaccharomyces pombe. The Surf-3 C-terminal anti-peptide serum detects a 32-kilodalton protein in other mammals, birds, and Xenopus but not in Drosophila and S. pombe. The possible effect of interaction of the Surf-3 ribosomal protein gene with adjacent genes in the Surfeit locus at the transcriptional or posttranscriptional level or both levels is discussed.
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Família Multigênica , Pseudogenes , Proteínas Ribossômicas/genética , Animais , Sequência de Bases , Embrião de Galinha , DNA Recombinante/análise , Imunofluorescência , Humanos , Immunoblotting , Camundongos , Ratos , Proteínas Ribossômicas/análise , SchizosaccharomycesRESUMO
Many studies have been conducted on the environmental impacts of combustion generated aerosols. Due to their complex composition and morphology, their chemical reactivity is not well understood and new developments of analysis methods are needed. We report the first demonstration of in-flight X-ray based characterizations of freshly emitted soot particles, which is of paramount importance for understanding the role of one of the main anthropogenic particulate contributors to global climate change. Soot particles, produced by a burner for several air-to-fuel ratios, were injected through an aerodynamic lens, focusing them to a region where they interacted with synchrotron radiation. X-ray photoelectron spectroscopy and carbon K-edge near-edge X-ray absorption spectroscopy were performed and compared to those obtained for supported samples. A good agreement is found between these samples, although slight oxidation is observed for supported samples. Our experiments demonstrate that NEXAFS characterization of supported samples provides relevant information on soot composition, with limited effects of contamination or ageing under ambient storage conditions. The highly surface sensitive XPS experiments of airborne soot indicate that the oxidation is different at the surface as compared to the bulk probed by NEXAFS. We also report changes in soot's work function obtained at different combustion conditions.
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INTRODUCTION: Pranlukast is a leukotriene receptor antagonist (LTRA) that is used as an additional controller of mild to moderate asthma. This study compared the efficacy and side effects of two bioequivalent preparations of pranlukast: original pranlukast (Onon(®); Ono Pharmaceutical, Japan) and a modified formulation of pranlukast (Prakanon(®); Yuhan Co, Korea) in patients with mild to moderate asthma. METHODS: Of the 34 subjects screened, 30 patients who were using standard medication to control asthma and scored less than 20 points on the Asthma Control Test(™) (ACT) were assigned randomly to one of the two groups in a prospective, open label, crossover study: group 1 received Prakanon(®) (150 mg/day) and group 2 received Onon(®) (450 mg/day) for 8 weeks each; after a 1-week rest period, the groups were switched to the alternative medication for further 8 weeks and monitored for 2 more weeks without study medication. Evaluation parameters included the ACT, quality of life questionnaire adult Korean asthmatics (QLQAKA), pulmonary function tests, peripheral blood tests, vital signs, and adverse events. RESULTS: Thirty patients were enrolled and 21 completed the trial: 10 in group 1 and 11 in group 2. The baseline data of the two groups did not differ. No statistical significant differences were observed in efficacy and lung function at each time and in changes from baseline value between the two kinds of pranlukast. The final asthma control rate was 81% with Prakanon(®) and 76% with Onon(®). There were no differences in vital signs and laboratory data at each time and in changes from baseline value between the two drugs. There were no differences in adverse events between the two drugs. The most common side effect was abdominal pain. Drug compliance was high, without differences between the two drugs. CONCLUSION: These findings suggest that Prakanon(®) which is an improved formulation of pranlukast at a lower dose than the original formulation, Onon(®), has a similar efficacy and side effect profile in the control of persistent asthma.
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The genomic structure and sequence of the human ribosomal protein L7a (rpL7a) and its transcriptional start sites have been determined. The gene contains eight exons and seven introns spread over 3179 bp. The human rpL7a gene is similar to other mammalian ribosomal protein genes in containing a short first exon, a short 5' untranslated leader and its transcriptional start sites at C residues embedded in a polypyrimidine tract. The 25 bp polypyrimidine tract containing the two human rpL7a start sites is the longest polypyrimide tract so far observed for a mammalian ribosomal protein gene.
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Cromossomos Humanos Par 9 , Família Multigênica/genética , Proteínas Ribossômicas/genética , Sequência de Bases , Éxons/genética , Expressão Gênica , Genoma , Humanos , Íntrons/genética , Dados de Sequência Molecular , Transcrição Gênica/genéticaRESUMO
The cho1/pss mutant of Saccharomyces cerevisiae, which is auxotrophic for choline or ethanolamine because of the deficiency in phosphatidylserine synthesis, grew in the presence of 0.05 mM phosphatidylcholine (PC) with octanoic acids (diC8PC) or decanoic acids (diC10PC), but not in the presence of PC with longer acyl residues. It did not grow in the presence of the soluble hydrolytic products of PC, phosphorylcholine or glycerophosphorylcholine, at comparable concentrations. Addition of 10 mM hemicholinium-3, a choline transport inhibitor, or disruption of the CTR gene, which encodes a choline transporter, inhibited the growth of the cho1/pss mutant in the presence of choline, but not in the presence of 0.1 mM diC8PC. Under diC8PC-supported growth conditions, octanoic acid was barely detectable in the cellular phospholipid fraction, but was recovered in the culture medium as the free acid, and the phosphatidylethanolamine (PE) content was low in comparison to the choline-supported conditions. These results suggest that PCs with short acyl residues were taken up by the cho1/pss mutant and remodeled as they were used, and that PCs with short acyl residues do not inhibit conversion of PE to PC. The current results provide a new direction in the analysis of intracellular phospholipid movement and metabolism in yeast.
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Fosfolipídeos/metabolismo , Saccharomyces cerevisiae/metabolismo , Caprilatos/metabolismo , Mutação , Fosfatidilcolinas/metabolismo , Fosfatidilserinas/biossíntese , Polissorbatos/farmacologia , Saccharomyces cerevisiae/crescimento & desenvolvimentoRESUMO
Thirty-nine previously untreated patients with stages III and IV ovarian carcinoma were treated with debulking surgery, followed by alternating combination chemotherapy with cisplatin, Adriamycin (Adria Laboratories, Columbus, Ohio), and cyclophosphamide (PAC); and hexamethylmelamine, cyclophosphamide, methotrexate, and 5-fluorouracil (HexaCAF). Of 19 patients with measureable disease at the onset of therapy, ten (53%) had at least a partial response to chemotherapy. Seven (18% of total) patients were found to be pathologically free of disease at secondlook surgery, but four patients relapsed 19 to 31 months after initiating therapy. The median progression-free survival period of all 39 patients entered into the study is 12 months, and the median crude survival is 21 months. The PAC/HexaCAF alternating combination chemotherapy regimen may be administered with moderate toxicity, but the treatment results are not superior to those reported for PAC or HexaCAF alone in advanced ovarian carcinoma.
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Adenocarcinoma/tratamento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Neoplasias Ovarianas/tratamento farmacológico , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Terapia Combinada , Feminino , Humanos , Pessoa de Meia-Idade , Neoplasias Ovarianas/patologia , Neoplasias Ovarianas/cirurgiaRESUMO
It was shown recently that exposure of the developing rat brain during the peak of synaptogenesis to commonly used general anesthetics can trigger widespread apoptotic neurodegeneration in many regions of the developing rat brain and persistent learning/memory deficits later on in life. To understand the mechanism by which general anesthetics induce apoptotic neuronal death we studied two common apoptotic pathways--the intrinsic and the extrinsic pathway--at different time points during synaptogenesis. We found that the intrinsic pathway is activated early on during anesthesia exposure (within two hours), as measured by the down-regulation of bcl-x(L), up-regulation of cytochrome c and the activation of caspase-9 in 7-day-old rats (the peak of synaptogenesis), but remains inactivated in 14-day-old rats (the end of synaptogenesis). The extrinsic pathway is activated later on (within six hours of anesthesia exposure), as measured by the up-regulation of Fas protein and the activation of caspase-8 in 7-day-old rats, but remains inactivated in 14-day-old rats. Anesthesia-induced apoptotic neurodegeneration is age dependent with vulnerability closely correlating with the timing of synaptogenesis, i.e. the developing brain is most sensitive at the peak of synaptogenesis (7 days old) and least sensitive at the end of synaptogenesis (14 days old).
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Anestesia , Apoptose/fisiologia , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Transdução de Sinais/fisiologia , Anestésicos Inalatórios/farmacologia , Animais , Apoptose/efeitos dos fármacos , Gasometria , Western Blotting , Caspases/metabolismo , Morte Celular/efeitos dos fármacos , Circulação Cerebrovascular/efeitos dos fármacos , Citocromos c/fisiologia , Ativação Enzimática/efeitos dos fármacos , Fluxometria por Laser-Doppler , Óxido Nitroso/farmacologia , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Proteína bcl-X/fisiologia , Receptor fas/biossínteseRESUMO
For industrial concerns, and more especially for nuclear applications, the characterization of soot is essential for predicting the behaviour of containment barriers in fire conditions. This study deals with the characterization (emission factor, composition, size, morphology, microstructure) of particles produced during thermal degradation of materials found in nuclear facilities (electrical cables, polymers, oil and solvents). Small-scale experiments have been conducted for oxygen concentrations [O2] ranging from 15% to 21% in order to imitate the oxygen depletion encountered during a confined fire. Particles denote distinct shapes, from aggregates composed of monomers with diameters ranging from 31.2 nm to 52.8 nm, to compact nanoparticles with diameters ranging from 15 nm to 400 nm, and their composition strongly depends on fuel type. Despite the organic to total carbon ratio (OC/TC), their properties are poorly influenced by the decrease in [O2]. Finally, two empirical correlations are proposed for predicting the OC/TC ratio and the monomer diameter, respectively, as a function of the fuel's carbon to hydrogen ratio and the emission factor.
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Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Incêndios , Centrais Nucleares , Material Particulado/análiseRESUMO
The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 µm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed.
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Unfolding and refolding kinetics of yeast phosphoglycerate kinase were studied by following the time-dependent changes of two signals: the ellipticity at 218 nm and 222 nm, and the fluorescence emission at 330 nm (following excitation at 295 nm). The protein is composed of two similar-sized structural domains. Each domain has been produced by recombinant DNA techniques. It has been previously demonstrated that the engineered isolated domains are able to fold into a quasinative structure (Minard, P., et al., 1989b, Protein Eng. 3, 55-60; Missiakas, D., Betton, J.M., Minard, P., & Yon, J.M., 1990, Biochemistry 29, 8683-8689). The behavior of the isolated domains was studied using the same two conformational probes as for the whole enzyme. We found that the refolding kinetics of each domain are multiphasic. In the whole protein, domain folding and pairing appeared to be simultaneous events. However, it was found that some refolding steps occurring during the refolding of the isolated C-domain are masked during the refolding of yeast phosphoglycerate kinase. The N-domain was also found to refold faster when it was isolated than when integrated.
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Fosfoglicerato Quinase/química , Fosfoglicerato Quinase/metabolismo , Dobramento de Proteína , Estrutura Secundária de Proteína , Saccharomyces cerevisiae/enzimologia , Guanidina , Guanidinas/farmacologia , Cinética , Modelos Moleculares , Fosfoglicerato Quinase/genética , Desnaturação Proteica , Engenharia de Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Fatores de TempoRESUMO
The two types of subunits alpha and beta constitutive of yeast phosphofructokinase have been separated by ion-exchange chromatography under denaturating conditions. Amino acid analysis and peptide mapping were performed on the isolated subunits. The frequence of most of the amino acids significantly differs between the two types of polypeptide chains. Moreover, tryptic peptide maps of alpha and beta subunits are clearly not superimposable. These chemical differences seem sufficient to account for the distinct catalytic and regulatory functions of beta and alpha subunits in the yeast phosphofructokinase reaction.
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Fosfofrutoquinase-1/isolamento & purificação , Saccharomyces cerevisiae/enzimologia , Aminoácidos/análise , Cromatografia em Camada Fina , Substâncias Macromoleculares , Peso Molecular , Fragmentos de Peptídeos/análise , Peptídeos/isolamento & purificação , TripsinaRESUMO
Phosphate ions were found to stabilize the native structure of phosphoglycerate kinase without modifying the folding pathway. The transition curves obtained from different signals: enzyme activity, ellipticity at 220 nm and fluorescence intensity at 336 nm (excitation at 292 nm) are shifted to smaller guanidine hydrochloride cm values in the absence of phosphate. The kinetic characteristics are qualitatively similar, unfolding rate constants being slightly smaller in the presence of phosphate. The mechanism by which the native structure of phosphoglycerate kinase is stabilized by phosphate probably occurs upon specific phosphate binding to the nucleotide beta- or gamma-phosphate binding site of nucleotides.