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1.
Physiol Res ; 71(5): 657-666, 2022 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-36047729

RESUMO

Stem cells have emerged as promising therapeutic options for several human diseases, including pulmonary fibrosis (PF). In this study, we investigated the therapeutic effects of adipose tissue-derived mesenchymal stem cells (ADMSCs) in the bleomycin-induced PF model rats and the underlying mechanisms. The PF model rats were generated by intratracheal injections of 5 mg/kg bleomycin sulfate. The ADMSC group rats were generated by injecting 2×10(6) ADMSCs via the tail vein at 0, 12, and 24 h after bleomycin injection. The control, PF, and ADMSC group rats were sacrificed on day 21 after bleomycin injections and the changes in lung histology and the levels of pro-inflammatory cytokines, collagen I, and caveolin-1 (Cav-1), and the activity of the NF-kappaB signaling pathway in the lung tissues was assessed by hematoxylin-eosin staining, ELISA, and western blotting assays. The lung tissues of the PF model rats showed significant infiltration of neutrophils, tissue destruction, and collagen deposition, but these effects were abrogated by the ADMSCs. The levels of pro-inflammatory cytokines such as IL-6, IL-1beta, and TGF-beta1 were elevated in the lung tissues and the bronchoalveolar lavage fluid (BALF) of the bleomycin-induced PF model rats, but these effects were reversed by the ADMSCs. The lung tissues of the PF model rats showed significant downregulation of Cav-1 and significantly higher activation of the pro-inflammatory NF-kappaB pathway. However, administration of the ADMSCs restored the expression levels of Cav-1 and suppressed the NF-kappaB signaling pathway in the lungs of the bleomycin-induced PF model rats. In conclusion, this study demonstrated that the ADMSCs protected against bleomycin-induced PF in the rat model by modulating the Cav-1/NF-kappaB axis.


Assuntos
Células-Tronco Mesenquimais , Pneumonia , Fibrose Pulmonar , Animais , Ratos , Bleomicina/toxicidade , Caveolina 1/metabolismo , Caveolina 1/farmacologia , Caveolina 1/uso terapêutico , Colágeno/metabolismo , Citocinas/metabolismo , Pulmão , Células-Tronco Mesenquimais/metabolismo , NF-kappa B/metabolismo , Pneumonia/metabolismo , Fibrose Pulmonar/induzido quimicamente , Fibrose Pulmonar/terapia , Fibrose Pulmonar/metabolismo , Ratos Sprague-Dawley , Transdução de Sinais
2.
Artigo em Chinês | MEDLINE | ID: mdl-34666446

RESUMO

Objective: To analyze the clinical manifestations of a patient with branchiootic syndrome(BOS) and her families and to carry out genetic testing in order to specify the biological pathogenesis. Methods: Clinical data of the patient and her families were collected. Genomic DNA in the peripheral blood of the proband and her family members was extracted. All exons of 406 deafness-related susceptible genes as well as their flanking regions were sequenced by high-throughput sequencing, and the mutation sites of the proband and her parents were validated by Sanger sequencing. Results: There were nine members in three generations, of whom four presented with hearing loss, preauricular fistula and branchial fistula which met the diagnostic criteria of BOS. Proband and her mother presented with auricle malformation and inner ear malformation. And no one had abnormalities in the kidneys of all the patients. Pedigree analysis revealed that the mode of inheritance in the family was consistent with the autosomal dominant pattern. Mutational analysis showed that all the affected patients detected a heterozygous frameshift variation c.1255delT in the EYA1 gene, which had not been reported. Genotype and phenotype were co-isolated in this family. Such a frameshift variation produced a premature termination codon, thereby causing premature termination of translation (p.C419VFS*12). ACMG identified that the mutation was pathogenic. This mutation was novel and not detected in controls. A heterozygous missense variation mutation c.403G>A(p.G135S) in EYA1 gene was also detected in three members of this family. ACMG identified that the mutation clinical significance was uncertain. However, two of whom were normal, which seemed the disease was not caused by this mutation in this family. Conclusions: A novel frameshift mutation in EYA1(c.1255delT) is the main molecular etiology of BOS in the Chinese family. This study expands the mutational spectrum of EYA1 gene. The clinical manifestations are heterogeneous among patients in this family. The diagnosis of BOS should combine gene tests with clinical phenotypes analysis.


Assuntos
Síndrome Brânquio-Otorrenal , Síndrome Brânquio-Otorrenal/genética , Análise Mutacional de DNA , Feminino , Testes Genéticos , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Mutação , Proteínas Nucleares , Linhagem , Proteínas Tirosina Fosfatases/genética
3.
Artigo em Chinês | MEDLINE | ID: mdl-33472302

RESUMO

Objective: To screen and analyze the mutations of MITF gene in two children of type Ⅱ Waardenburg syndrome (WS2) from different families in Yunnan,China,and to explore the possible molecular pathogenesis. Methods: With informed consent, medical history collection, physical examinations, audiological evaluation, and high resolution computer tomography (HRCT) scan of temporal bone were performed on the two WS2 probands and their family members. Genomic DNA was extracted from peripheral blood of all individuals. The coding regions including all exons, part of introns and promoters of MITF, PAX3, SOX10, SNAI2, END3, ENDRB, and KITLG genes were sequenced by high-throughput sequencing. According to the results of high-throughput sequencing, pathogenic mutations detected in the probands and their parents were verified by Sanger sequencing. Results: The proband 1 carried c.641_643delGAA mutation in the 7th exon of MITF gene, which was a frame-shift mutation resulting in an amino acid change of p.214delR. It was a de novo mutation as the parents of proband 1 showed no variation on this site. The proband 2 carried heterozygous loss of the large fragment ranging from exon 1 to exon 9 of MITF gene, which defected the function of MITF protein. Conclusion: Genetic examinations provide important evidence for diagnosis of Waardenburg syndrome. Heterozygous mutation c.641_643delGAA and heterozygous loss of the large fragment ranging from exon 1 to exon 9 of MITF gene might be the molecular pathogenesis of the two WS2 probands in this study.


Assuntos
Síndrome de Waardenburg , Povo Asiático/genética , Criança , China , Humanos , Mutação , Linhagem , Fatores de Transcrição SOXE/genética , Síndrome de Waardenburg/genética
5.
Artigo em Chinês | MEDLINE | ID: mdl-29798205

RESUMO

Objective:To investigate the surgical treatment of cholesteatoma of the middle ear. Method:A retrospective analysis of patients from June 2013 to July 2016 diagnosed as cholesteatoma. 137 ears were divided into A group (retaining part of the external auditory canal posterior wall with epitympanoplasty in soft wall reconstruction for 75 ears) and B group (canal wall down mastoidotympanoplasty for 62 ears). the extent and damage of cholesteatoma were observed, comparing the time of dry ear and epithelial postoperative, the incidence of complications such as dizziness and hearing changes. Result:compared with B group, the postoperative dry ear time, epithelial time and hearing improvement in the A group were obviously improved, and the incidence of vertigo after operation was decreased, and the anatomical and physiological functions of the external auditory canal were protected. Conclusiont:The technique of retaining part of the external auditory canal posterior wall with epitympanoplasty in soft wall reconstruction is conductive to the removal of lesions and normal anatomical and physiological protection to external auditory canal, can prevent the forming of the abstraction pocket effectively and the recurrence of cholesteatoma, has clinical and practical value.


Assuntos
Colesteatoma da Orelha Média/cirurgia , Timpanoplastia , Meato Acústico Externo , Orelha Média , Seguimentos , Humanos , Estudos Retrospectivos , Resultado do Tratamento
6.
Artigo em Chinês | MEDLINE | ID: mdl-29771067

RESUMO

Objective:To discuss the minimally invasive surgical techniques and the effect of cochlear implantation with round window pathways in young children(≤3 years).Method:One hundred and sixty patients with bilateral profound sensorineural hearin loss received MED-EL cochlear implantation,including 144 cases of normal middle and inner ear,4 cases of Mondini deformity,12 cases of large vestibular aqueduct syndrome.Result:Of 160 patients underwent CIs,148 patients were performed with round window pathways,the rate was 92.5%. Iit's difficult to exposure round window in 12 patients,performing from promontory.All electrodes of 158 cases with unilateral CI and 2 cases with bilateral CI were implanted successfully,in which the CI went normally and electrode array were protected well.All implant devices had worked normally and all patients had performed well during an average follow-up period of 8 month-3 years.Post-operatively complications of cerebrospinal fluid leakage,facial nerve injury haven't been found.Conclusion:Cochlear implantation could be performed in patients wit with round window pathways,and it is a safe and effective way in young children.


Assuntos
Implante Coclear/métodos , Implantes Cocleares , Janela da Cóclea/cirurgia , Criança , Pré-Escolar , Orelha Interna/cirurgia , Feminino , Perda Auditiva Neurossensorial/cirurgia , Humanos , Lactente , Masculino , Procedimentos Cirúrgicos Minimamente Invasivos , Complicações Pós-Operatórias , Síndrome , Aqueduto Vestibular
7.
Braz. j. med. biol. res ; 48(12): 1145-1150, Dec. 2015. tab, graf
Artigo em Inglês | LILACS | ID: lil-762921

RESUMO

This study investigated the value of computed tomography (CT) in the diagnosis and treatment of hepatic veno-occlusive disease (HVOD) caused by Sedum aizoon (SA). The clinical manifestations, treatment results, imaging findings, and histological findings of the liver were analyzed in 39 patients with HVOD caused by SA. Hepatomegaly, liver dysfunction, abdominal effusion, and geographic density changes on liver CT scans were found in all 39 patients. The pathological findings of histological liver examination included swelling and point-like necrosis of liver cells, significant expansion and congestion of the sinuses, endothelial swelling, and wall thickening with incomplete lumen occlusion of small liver vessels. CT geographic density changes were confirmed by histological examination of the liver in 18 patients. Sixteen patients with small amounts of ascites that started within 4 weeks of treatment recovered completely or significantly improved after symptomatic and supportive treatment. However, only 43.75% of the patients with larger amounts of ascites improved following symptomatic and supportive treatment. In conclusion, liver CT examination is a valuable, safe, and noninvasive tool for the diagnosis of HVOD caused by SA. In selected cases, liver CT examination may replace liver biopsy and histological analysis.


Assuntos
Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medicamentos de Ervas Chinesas/intoxicação , Hepatopatia Veno-Oclusiva , Circulação Hepática/efeitos dos fármacos , Sedum/intoxicação , Ascite/etiologia , Biópsia , China , Hepatopatia Veno-Oclusiva/etiologia , Hepatopatia Veno-Oclusiva/patologia , Necrose , Estudos Retrospectivos , Sedum/classificação , Tomografia Computadorizada por Raios X
8.
Braz J Med Biol Res ; 48(12): 1145-50, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26517336

RESUMO

This study investigated the value of computed tomography (CT) in the diagnosis and treatment of hepatic veno-occlusive disease (HVOD) caused by Sedum aizoon (SA). The clinical manifestations, treatment results, imaging findings, and histological findings of the liver were analyzed in 39 patients with HVOD caused by SA. Hepatomegaly, liver dysfunction, abdominal effusion, and geographic density changes on liver CT scans were found in all 39 patients. The pathological findings of histological liver examination included swelling and point-like necrosis of liver cells, significant expansion and congestion of the sinuses, endothelial swelling, and wall thickening with incomplete lumen occlusion of small liver vessels. CT geographic density changes were confirmed by histological examination of the liver in 18 patients. Sixteen patients with small amounts of ascites that started within 4 weeks of treatment recovered completely or significantly improved after symptomatic and supportive treatment. However, only 43.75% of the patients with larger amounts of ascites improved following symptomatic and supportive treatment. In conclusion, liver CT examination is a valuable, safe, and noninvasive tool for the diagnosis of HVOD caused by SA. In selected cases, liver CT examination may replace liver biopsy and histological analysis.


Assuntos
Medicamentos de Ervas Chinesas/intoxicação , Hepatopatia Veno-Oclusiva/diagnóstico por imagem , Circulação Hepática/efeitos dos fármacos , Sedum/intoxicação , Adulto , Idoso , Ascite/etiologia , Biópsia , China , Feminino , Hepatopatia Veno-Oclusiva/etiologia , Hepatopatia Veno-Oclusiva/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Necrose , Estudos Retrospectivos , Sedum/classificação , Tomografia Computadorizada por Raios X
9.
Curr Med Chem ; 19(16): 2652-64, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22506770

RESUMO

The bryostatins, powerful protein kinase C (PKC) agonists, are a family of complex macrolactone natural products. They are originally isolated from the marine bryozoan Bugula neritina. So far tweenty bryostatins have been obtained naturally and exhibit a remarkable range of biological activities, including antineoplastic activity, synergistic chemotheoreputic activity, cognition and memory enhancement, etc. Of the 20 known members, the most extensively studied is bryostatin 1. The effects of bryostatin 1 are mainly linked to its ability of selectively modulating the function of various individual protein kinase C (PKC) isozymes. Moreover, bryostatin 1, or in combination with other agents, has been proposed for phase I and phase II clinical trials. The bryostatins have excellent biological properties, but are scarce in nature. Therefore, it has attracted considerable interests in structural modification over the past two decades. In this review, we will attempt to summarize the main developments that have occurred in the structure-activity relationship and biology of bryostatins over the period 1982-2011.


Assuntos
Briostatinas/farmacologia , Proteína Quinase C/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Briostatinas/química , Humanos , Proteína Quinase C/química , Inibidores de Proteínas Quinases/química
10.
Mini Rev Med Chem ; 11(9): 771-821, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21651464

RESUMO

Dihydropyrazole, a small bioactive molecule, is a prominent structural motif found in numerous pharmaceutically active compounds. The chiral dihydropyrazole structure has been demonstrated to bear important biological activities such as anticancer, antimicrobial, antimalarial, antinociceptive, antiviral, antitubercular, antiinflammatory, anticonvulsant and steroidal, and can also act as MAO inhibitors, CB1 receptor antagonists and nitric oxide synthase inhibitors. The review describes the latest advances in the synthesis of dihydropyrazole derivatives incorporating physiologically active substances. It is the first attempt at a general and systematic account of the extensive literature data on this subject.


Assuntos
Desenho de Fármacos , Pirazóis/química , Analgésicos/síntese química , Analgésicos/química , Analgésicos/farmacologia , Anti-Infecciosos/síntese química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Anti-Inflamatórios/síntese química , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Anticonvulsivantes/síntese química , Anticonvulsivantes/química , Anticonvulsivantes/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Monoaminoxidase/química , Monoaminoxidase/metabolismo , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Pirazóis/síntese química , Pirazóis/farmacologia , Receptor CB1 de Canabinoide/antagonistas & inibidores , Receptor CB1 de Canabinoide/metabolismo , Relação Estrutura-Atividade
11.
Cell Mol Life Sci ; 61(19-20): 2437-45, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15526152

RESUMO

Aminoacyl-tRNA (transfer RNA) synthetases are essential components of the cellular translation machinery as they provide the ribosome with aminoacyl-tRNAs. Aminoacyl-tRNA synthesis is generally well understood. However, the mechanism of Cys-tRNACys formation in three methanogenic archaea ( Methanocaldococcus jannaschii, Methanothermobacter thermautotrophicus and Methanopyrus kandleri) is still unknown, since no recognizable gene for a canonical cysteinyl-tRNA synthetase could be identified in the genome sequences of these organisms. Here we review the different routes recently proposed for Cys-tRNACys formation and discuss its possible link with cysteine biosynthesis in these methanogenic archaea.


Assuntos
Archaea/metabolismo , Cisteína/biossíntese , Genes Arqueais , Aminoacil-RNA de Transferência/química , Sítios de Ligação , Cisteína/química , Metano/química , Modelos Biológicos , Modelos Moleculares , Filogenia , Biossíntese de Proteínas , Conformação Proteica , RNA/química
12.
Acta Biochim Pol ; 48(2): 313-21, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11732603

RESUMO

Translation is the process by which ribosomes direct protein synthesis using the genetic information contained in messenger RNA (mRNA). Transfer RNAs (tRNAs) are charged with an amino acid and brought to the ribosome, where they are paired with the corresponding trinucleotide codon in mRNA. The amino acid is attached to the nascent polypeptide and the ribosome moves on to the next codon. Thus, the sequential pairing of codons in mRNA with tRNA anticodons determines the order of amino acids in a protein. It is therefore imperative for accurate translation that tRNAs are only coupled to amino acids corresponding to the RNA anticodon. This is mostly, but not exclusively, achieved by the direct attachment of the appropriate amino acid to the 3'-end of the corresponding tRNA by the aminoacyl-tRNA synthetases. To ensure the accurate translation of genetic information, the aminoacyl-tRNA synthetases must display an extremely high level of substrate specificity. Despite this highly conserved function, recent studies arising from the analysis of whole genomes have shown a significant degree of evolutionary diversity in aminoacyl-tRNA synthesis. For example, non-canonical routes have been identified for the synthesis of Asn-tRNA, Cys-tRNA, Gln-tRNA and Lys-tRNA. Characterization of non-canonical aminoacyl-tRNA synthesis has revealed an unexpected level of evolutionary divergence and has also provided new insights into the possible precursors of contemporary aminoacyl-tRNA synthetases.


Assuntos
Evolução Molecular , Genômica , Aminoacil-RNA de Transferência/biossíntese , Aminoacil-RNA de Transferência/genética , Aminoacil-tRNA Sintetases/genética , Aminoacil-tRNA Sintetases/metabolismo , Filogenia , Biossíntese de Proteínas , RNA Mensageiro/genética
13.
FASEB J ; 15(3): 775-84, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11259396

RESUMO

The resumption of meiosis is regulated by meiosis-preventing and meiosis-activating substances in testes and ovaries. Certain C29 precursors of cholesterol are present at elevated levels in gonadal tissue, but the mechanism by which these meiosis-activating sterols (MAS) accumulate has remained an unresolved question. Here we report that progestins alter cholesterol synthesis in HepG2 cells and rat testes to increase levels of major MAS (FF-MAS and T-MAS). These C29 sterols accumulated as a result of inhibition of Delta24-reduction and 4alpha-demethylation. Progesterone, pregnenolone, and 17alpha-OH-pregnenolone were potent inhibitors of Delta24-reduction in an in vitro cell assay and led to the accumulation of desmosterol, a Delta5,24 sterol precursor of cholesterol. A markedly different effect was observed for 17alpha-OH-progesterone, which caused the accumulation of sterols associated with inhibition of 4alpha-demethylation. The flux of 13C-acetate into lathosterol and cholesterol was decreased by progestins as measured by isotopomer spectral analysis, whereas newly synthesized MAS accumulated. The combined evidence that MAS concentrations can be regulated by physiological levels of progestins and their specific combination provides a plausible explanation for the elevated concentration of MAS in gonads and suggests a new role for progestins in fertility.


Assuntos
Colestadienóis/farmacologia , Colesterol/biossíntese , Progestinas/farmacologia , Esteróis/biossíntese , Testículo/efeitos dos fármacos , Animais , Peso Corporal , Colestadienóis/metabolismo , Colesterol/metabolismo , Antagonistas de Estrogênios/farmacologia , Humanos , Hidroxiprogesteronas/metabolismo , Hidroxiprogesteronas/farmacologia , Masculino , Meiose/fisiologia , Miconazol/farmacologia , Mifepristona/farmacologia , Progestinas/metabolismo , Ratos , Análise Espectral , Tamoxifeno/farmacologia , Testículo/citologia , Testículo/metabolismo , Células Tumorais Cultivadas
14.
Biol Reprod ; 64(1): 80-9, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11133661

RESUMO

This study was carried out to examine the effects of the meiosis-activating C(29) sterol, 4,4-dimethyl-5 alpha-cholesta-8,14, 24-trien-3 beta-ol (FF-MAS), on mouse oocyte maturation in vitro. Cumulus cell-enclosed oocytes (CEO) and denuded oocytes (DO) from hormonally primed, immature mice were cultured 17-18 h in minimum essential medium (MEM) containing 4 mM hypoxanthine plus increasing concentrations of FF-MAS. The sterol induced maturation in DO with an optimal concentration of 3 microg/ml but was without effect in CEO, even at concentrations as high as 10 microg/ml. Some stimulation of maturation in hypoxanthine-arrested CEO was observed when MEM was replaced by MEMalpha. Interestingly, the sterol suppressed the maturation of hypoxanthine-arrested CEO in MEM upon removal of glucose from the medium. FF-MAS also failed to induce maturation in DO when meiotic arrest was maintained with dibutyryl cAMP (dbcAMP). The rate of maturation in FF-MAS-stimulated, hypoxanthine-arrested DO was slow, as more than 6 h of culture elapsed before significant meiotic induction was observed, and this response required the continued presence of the sterol. Although the oocyte took up radiolabeled lanosterol, such accumulation was restricted by the presence of cumulus cells. In addition, lanosterol failed to augment FSH-induced maturation and was even inhibitory at a high concentration. Moreover, the downstream metabolite, cholesterol, augmented the inhibitory action of dbcAMP on maturation in both CEO and DO. Two inhibitors of 14 alpha-demethylase, ketoconazole, and 14 alpha-ethyl-5 alpha-cholest-7-ene-3 beta, 15 alpha-diol that can suppress FF-MAS production from lanosterol failed to block consistently FSH-induced maturation. These results confirm the stimulatory action of FF-MAS on hypoxanthine-arrested DO but do not support a universal meiosis-inducing function for this sterol.


Assuntos
Colestenos/farmacologia , Oócitos/citologia , Animais , Bucladesina/farmacologia , Células Cultivadas , Colestenos/administração & dosagem , Colesterol/farmacologia , Meios de Cultura , Inibidores Enzimáticos/farmacologia , Feminino , Hormônio Foliculoestimulante/farmacologia , Hipoxantina/farmacologia , Cetoconazol/farmacologia , Lanosterol/metabolismo , Meiose/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Folículo Ovariano/citologia
15.
J Lipid Res ; 38(8): 1685-701, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9300791

RESUMO

Gas chromatography-mass spectrometry (GC-MS) and GC are commonly used methods for the identification and quantitation of sterols from samples of biological origin. To investigate the utility and limitations of these methods, we have determined gas chromatographic mobilities and mass spectral properties of 5alpha-cholestan-3beta-ol and 26 unsaturated C27 sterols as their acetate and trimethylsilyl (TMS) ether derivatives by GC and GC-MS. The GC retention data showed that numerous sterols were essentially coeluted on capillary GC columns coated with either 5% phenyl-95% methyl polysiloxane or polyethylene glycol, although the peaks were more widely dispersed on the latter column. Mass spectra of many groups of sterol isomers were also quite similar. Sterol mixtures of any complexity are likely to contain coeluting components, and attempts to establish structures based on mass spectra that may represent a mixture of sterol isomers could easily lead to errors. Our results demonstrate that GC and GC-MS alone cannot generally be used for rigorous structure determinations of individual components in mixtures of unsaturated sterols. However, all but a few of the 26 sterols could be distinguished by their combined chromatographic mobilities on the two GC columns coupled with critical examination of their mass spectra. GC-MS analysis of appropriate sterol subclasses or preferably individual sterol components obtained by prior purification by other methods may provide valuable supporting evidence for the identification of sterol structures. Reliability of identification is dependent upon careful attention to GC and MS conditions, calibration of GC and MS data with authentic sterol standards, and consideration of possible decomposition under GC conditions and of the effect of overloading on GC retention times.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Esteróis/análise , Acetatos , Cromatografia Gasosa/métodos , Cromatografia Gasosa/normas , Cromatografia Gasosa/tendências , Estudos de Avaliação como Assunto , Cromatografia Gasosa-Espectrometria de Massas/normas , Cromatografia Gasosa-Espectrometria de Massas/tendências , Estrutura Molecular , Padrões de Referência , Estereoisomerismo , Esteróis/química , Esteróis/normas , Compostos de Trimetilsilil
16.
J Biol Chem ; 272(15): 10072-9, 1997 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-9092551

RESUMO

We have expressed the RecD subunit of the RecBCD enzyme from Escherichia coli as a fusion protein with a 31-amino acid NH2-terminal extension including 6 consecutive histidine residues (HisRecD). The overexpressed fusion protein can be purified in urea-denatured form by metal chelate affinity chromatography. The mixture of renatured HisRecD protein and the RecB and RecC proteins has a high level of ATP-dependent nuclease activity with either single- or double-stranded DNA, enhanced DNA unwinding activity, enhanced ATP hydrolysis activity in the presence of a small DNA oligomer cosubstrate, and chi-cutting activity. These are all characteristics of the RecBCD holoenzyme. The HisRecD protein by itself hydrolyzes ATP in the presence of high concentrations of single-stranded DNA (polydeoxythymidine). The activity is unstable at 37 degrees C, but is measurable at room temperature (about 23 degrees C). The HisRecD has very little ATPase activity in the presence of a much shorter single-stranded DNA (oligodeoxy(thymidine)12). HisRecD hydrolyzes ATP more efficiently than GTP and UTP, and has very little activity with CTP. We also purified a fusion protein containing a Lys to Gln mutation in the putative ATP-binding site of RecD. This mutant protein has no ATPase activity, indicating that the observed ATP hydrolysis activity is intrinsic to the RecD protein itself.


Assuntos
Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , DNA Helicases/química , Endodesoxirribonucleases/química , Proteínas de Escherichia coli , Exodesoxirribonucleases/química , Histidina , Cromatografia de Afinidade , DNA de Cadeia Simples/metabolismo , Eletroforese em Gel de Poliacrilamida , Exodesoxirribonuclease V , Hidrólise , Conformação Proteica
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