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1.
Dis Esophagus ; 30(8): 1-6, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28575244

RESUMO

Gastric pull-up is a common procedure to reconstruct the continuity of the upper digestive tract after esophageal resection. However, this technique sometimes causes postoperative anastomotic leakage or stricture, resulting from insufficient blood flow at the distal end. To overcome this problem, additional microvascular venous anastomoses were performed. The purpose of this study was to compare the outcomes of post-surgical anastomotic leakage and stricture in patients with and without additional microvascular venous superdrainage after cervical esophageal and hypopharyngeal resection and gastric tube reconstruction. A total of 29 consecutive patients with esophageal or hypopharyngeal cancer who underwent total esophagectomy and hypopharyngectomy with gastric tube reconstruction in the National Organization Nagasaki Medical Center between April 2014 and May 2016 were analyzed in this study. Of these patients, 20 underwent additional venous anastomoses (superdrainage group), and 9 did not undergo additional procedures (standard group). We compared the frequency of post-surgical stricture and leakage in the two groups retrospectively. Three of nine patients (33.3%) developed postoperative leakage in the standard group, and 1 of 20 (5.0%) did so in the superdrainage group. Six of nine patients (66.7%) showed postoperative anastomotic stricture in the standard group, but none did so in the superdrainage group. Patients who did not undergo additional venous superdrainage were significantly more likely to develop postsurgical leakage (P < 0.05, Chi-square test) and anastomotic stricture (P < 0.001, Chi-square test). Our study revealed that only additional venous anastomoses could reduce the incidence of postoperative anastomotic leakage and stricture. This procedure is of merit to perform after total esophagectomy and hypopharyngectomy with gastric tube reconstruction.


Assuntos
Fístula Anastomótica/prevenção & controle , Drenagem/métodos , Estenose Esofágica/prevenção & controle , Esofagoplastia/métodos , Esôfago/cirurgia , Microvasos/cirurgia , Idoso , Idoso de 80 Anos ou mais , Anastomose Cirúrgica/métodos , Fístula Anastomótica/etiologia , Estenose Esofágica/etiologia , Esofagectomia/efeitos adversos , Esôfago/irrigação sanguínea , Feminino , Humanos , Hipofaringe/cirurgia , Masculino , Pessoa de Meia-Idade , Pescoço/cirurgia , Estudos Retrospectivos , Estômago/irrigação sanguínea , Estômago/cirurgia , Resultado do Tratamento
2.
Sci Technol Adv Mater ; 15(5): 055007, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27877719

RESUMO

The transport and magnetic properties of the tetragonal Fe[Formula: see text]S were investigated using magnetoresistivity and magnetization within [Formula: see text] K, [Formula: see text] 70 kOe and [Formula: see text] 3.0 GPa. In addition, room-temperature x-ray diffraction and photoelectron spectroscopy were also applied. In contrast to previously reported nonmetallic character, Fe[Formula: see text]S is intrinsically metallic but due to a presence of a weak localization such metallic character is not exhibited below room temperature. An applied pressure reduces strongly this additional resistive contribution and as such enhances the temperature range of the metallic character which, for ∼3 GPa, is evident down to 75 K. The absence of superconductivity as well as the mechanism behind the weak localization will be discussed.

3.
Pharmazie ; 68(5): 349-54, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23802432

RESUMO

AS1924269-00 is a promising orally applicable anticoagulant that inhibits FVIIa but has very low oral absorption. Therefore, in this study, we aimed to develop a prodrug of AS1924269-00, which possesses a carbamate-added amidine functional group, with high membrane permeability. We investigated the pharmacokinetics of the carbamate-type prodrug of AS1924269-00 in rats. The Caco-2 cell monolayer was used as an in vitro model and in parallel an artificial membrane permeability assay (PAMPA) was performed to examine the transport mechanisms of the prodrug. The bioavailability of the active form was determined to be only 0.3% in rats, but the oral absorption of the prodrug was markedly improved, and its bioavailability was 36%. Our in vivo result was consistent with the finding that compared to AS1924269-00, the prodrug showed favorable permeability in Caco-2 cells and PAMPA. We introduced carbamate into the amidine functional group of the FVIIa inhibitor, which possesses the amidine backbone, and converted it to a prodrug using carboxylic acid ethyl ester. This novel prodrug had favorable absorption and membrane permeability in vivo and in vitro. Thus, we suggest a clinical application of the carbamate-added amidine prodrug of the FVIIa inhibitor.


Assuntos
Amidinas/farmacocinética , Anticoagulantes/farmacocinética , Fator VIIa/antagonistas & inibidores , Fenoxiacetatos/farmacocinética , Amidinas/administração & dosagem , Animais , Anticoagulantes/administração & dosagem , Células CACO-2 , Cromatografia Líquida de Alta Pressão , Meia-Vida , Humanos , Indicadores e Reagentes , Masculino , Espectrometria de Massas , Membranas Artificiais , Permeabilidade , Fenoxiacetatos/administração & dosagem , Ratos , Ratos Sprague-Dawley
4.
Pharmazie ; 68(6): 406-13, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23875246

RESUMO

We recently developed a prodrug (AS1932804-00, CMP) of the novel FVIIa inhibitor AS1924269-00, which possesses a carbamate amidine backbone. In addition, we developed another type of prodrug (AS1927819-00, OXP) with an oxime amidine backbone. In this study, we investigated the efficiency of conversion of these novel FVIIa prodrugs to their active forms by evaluating the production of the active form in vitro by using microsomes, mitochondria, and cryopreserved hepatocytes, and compared it with the in vivo conversion mechanisms of the prodrugs (oxime amidine vs. carbamate amidine). We observed that OXP and CMP showed improved oral absorption, and the efficiency of conversion of CMP to the active form was higher than that of OXP. The in vivo rate of conversion of OXP to its active form was low in rats, and compared to liver microsomes and mitochondria, cryopreserved hepatocytes supplemented with serum and coenzymes were an appropriate metabolic test tool. On the other hand, the efficiency of conversion of CMP to its active from could be appropriately evaluated using small intestinal microsomes. The development of a prodrug can be optimized when information about the stability of carboxylic acid esters in the presence of serum esterases, membrane permeability of intermediate forms, and differential tissue specificity to metabolic activities for carbamate and oxime backbones of amidine can be obtained.


Assuntos
Anticoagulantes/farmacocinética , Fator VIIa/antagonistas & inibidores , Fenoxiacetatos/farmacocinética , Animais , Azetidinas/farmacocinética , Benzilaminas/farmacocinética , Biotransformação , Hepatócitos/metabolismo , Técnicas In Vitro , Mucosa Intestinal/metabolismo , Cinética , Microssomos Hepáticos/metabolismo , Mitocôndrias Hepáticas/metabolismo , NAD/metabolismo , NADP/metabolismo , Pró-Fármacos/metabolismo , Ratos
5.
Cell Death Differ ; 15(6): 1073-83, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18259196

RESUMO

Mitochondrial proteins such as cytochrome c, Smac/DIABLO and Omi/HtrA2 play important roles in the cell death pathways of mammalian cells. In Drosophila, the role of mitochondria in cell death is less clear. Here, we report the identification and characterization of the Drosophila ortholog of human Omi/HtrA2. We show that Drosophila Omi/HtrA2 is imported into the mitochondria where it undergoes proteolytic maturation to yield two isoforms, dOmi-L and dOmi-S. dOmi-L contains a canonical N-terminal IAP-binding motif (AVVS), whereas dOmi-S contains a distinct N-terminal motif (SKMT). DIAP1 was able to bind to both isoforms via its BIR1 and BIR2 domains. This resulted in cleavage of the linker region of DIAP1 between the BIR1 and BIR2 domains and further degradation of the BIR1 domain by the proteolytic activity of dOmi. The binding of DIAP1 to dOmi also resulted in DIAP1-mediated polyubiquitination of dOmi, suggesting that DIAP1 could target dOmi for proteasomal degradation. Consistent with this, expression of DIAP1 in Drosophila eye discs protected them from dOmi-induced eye ablation, indicating that DIAP1 plays an important role in protecting cells from the potentially lethal effects of dOmi. The ability of IAPs to bind to and ubiquitinate mitochondrial proteins such as dOmi may be a key conserved function to counterbalance the lethal effects of these proteins if accidentally released into the cytosol.


Assuntos
Apoptose , Proteínas de Drosophila/metabolismo , Drosophila/enzimologia , Proteínas Inibidoras de Apoptose/metabolismo , Proteínas Mitocondriais/metabolismo , Serina Endopeptidases/metabolismo , Motivos de Aminoácidos , Animais , Caspases/metabolismo , Citosol/enzimologia , Drosophila/citologia , Drosophila/crescimento & desenvolvimento , Proteínas de Drosophila/antagonistas & inibidores , Proteínas de Drosophila/química , Olho/citologia , Olho/enzimologia , Olho/crescimento & desenvolvimento , Serina Peptidase 2 de Requerimento de Alta Temperatura A , Proteínas Mitocondriais/análise , Proteínas Mitocondriais/antagonistas & inibidores , Proteínas Mitocondriais/química , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Serina Endopeptidases/química , Ubiquitinação
6.
J Orthop Surg (Hong Kong) ; 17(1): 36-41, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19398791

RESUMO

PURPOSE: To report mid-term results of total hip arthroplasty (THA) using the Opti-Fix Plus Hip System (Opti-Fix Hip), and to assess the correlations between peri-implant bone changes and the distal medullary occupancy rate. METHODS: 11 men (13 hips) and 53 women (58 hips) aged 24 to 87 (mean, 61) years underwent THA using the Opti-Fix Hip, with a modular stem and a distal sleeve, and were followed up for a mean of 6.5 (range, 4.8-9.6) years. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) hip score. Implant stability, bone changes around the implant, and the occupancy rate of the stem in the medullary space were examined radiologically. Bone changes around the implant were assessed based on the radiological evidence of a pedestal, osteolysis, stress shielding, and radiolucent lines. RESULTS: The mean JOA score increased significantly after surgery and was maintained at the latest follow-up. Around the acetabular and femoral components respectively, 38 and 58 hips had radiolucent lines, whereas one and 54 hips developed osteolysis. A pedestal appeared in 21 hips and grade-III or higher stress shielding in 30 hips. Two hips showed loosening of the acetabular components, but none in the femoral components. Osteolysis around the stem was frequently observed in hips with poor distal medullary occupancy. CONCLUSION: Clinical and radiological outcomes of the Opti-Fix Hip were favourable. The low incidence of osteolysis in the distal stem suggests that the proximal circumferential porous coating was effective. Minor osteolysis around the proximal stem was frequently observed, indicating early excessive wear of the polyethylene liner. Its high distal medullary occupancy rate could inhibit stem micromotion and aseptic loosening.


Assuntos
Artroplastia de Quadril/instrumentação , Necrose da Cabeça do Fêmur/cirurgia , Prótese de Quadril , Osteoartrite do Quadril/cirurgia , Osteólise/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Falha de Equipamento , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Osteólise/diagnóstico por imagem , Desenho de Prótese , Radiografia , Amplitude de Movimento Articular , Resultado do Tratamento , Adulto Jovem
7.
Acta Neurochir Suppl ; 103: 29-36, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18496942

RESUMO

BACKGROUND: The thalamic cavernous angioma (CA) represents a neurosurgical challenge because of the critical neurologic functions of the thalamus and its surrounding structures and of their deep location inside the brain. Although the natural history of the thalamic CA remains undefined, several studies suggest the poor outcome of those patients especially if the symptomatic thalamic CA is treated conservatively. We describe the advantage of the paraculminar supracerebellar approach to the lesions in the brainstem. OBJECTIVE: We studied the usefulness and the safety of the paraculminar supracerebellar infratentorial transtentorial approach for the patients with thalamic CA. METHODS: One hundred and ninety two consecutive patients with CA were treated at the Department of Neurosurgery in the Zurich University Hospital between 1993 and 2003. Among these patients, we analyzed six patients (four female, mean age 43) with thalamic CA who underwent surgical removal with the paraculminar supracerebellar transtentorial approach. We retrospectively reviewed their medical charts, the neuroradiological images, and the operative notes/video records. RESULTS: Four patients of the six presented with thalamic hemorrhage. CA existed in the left thalamus in four patients and in the right in two. Preoperative symptoms included sensorimotor disturbance (three cases), double vision (three cases), Parinaud syndrome (one case), and thalamic pain (one case). All patients had the thalamic CA completely removed without any postoperative deterioration. CONCLUSIONS: This study suggests that for the removal of thalamic cavernous angioma the paraculminar supracerebellar infratentorial transtentorial approach provides the spacious surgical field with reduced risks of damaging and sacrificing surrounding vascular and neuronal system. This approach could proffer one of the best and safest surgical routes for the radical removal of thalamic cavernous angioma.


Assuntos
Neoplasias Encefálicas/cirurgia , Hemangioma Cavernoso/cirurgia , Procedimentos Neurocirúrgicos/métodos , Tálamo/cirurgia , Adulto , Neoplasias Encefálicas/patologia , Seio Cavernoso/patologia , Seio Cavernoso/cirurgia , Feminino , Hemangioma Cavernoso/patologia , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Neuronavegação/métodos , Estudos Retrospectivos , Tálamo/patologia , Tomografia Computadorizada por Raios X/métodos , Resultado do Tratamento
8.
Curr Biol ; 9(21): 1267-70, 1999 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-10556094

RESUMO

During the development of the nervous system embryonic neurons are incorporated into neural networks that underlie behaviour. For example, during embryogenesis in Drosophila, motor neurons in every body segment are wired into the circuitry that drives the simple peristaltic locomotion of the larva. Very little is known about the way in which the necessary central synapses are formed in such a network or how their properties are controlled. One possibility is that presynaptic and postsynaptic elements form relatively independently of each other. Alternatively, there might be an interaction between presynaptic and postsynaptic neurons that allows for adjustment and plasticity in the embryonic network. Here we have addressed this issue by analysing the role of synaptic transmission in the formation of synaptic inputs onto identified motorneurons as the locomotor circuitry is assembled in the Drosophila embryo. We targeted the expression of tetanus toxin light chain (TeTxLC) to single identified neurons using the GAL4 system. TeTxLC prevents the evoked release of neurotransmitter by enzymatically cleaving the synaptic-vesicle-associated protein neuronal-Synaptobrevin (n-Syb) [1]. Unexpectedly, we found that the cells that expressed TeTxLC, which were themselves incapable of evoked release, showed a dramatic reduction in synaptic input. We detected this reduction both electrophysiologically and ultrastructurally.


Assuntos
Drosophila/fisiologia , Sinapses/fisiologia , Transmissão Sináptica/fisiologia , Toxina Tetânica/farmacologia , Animais , Rede Nervosa , Sinapses/ultraestrutura , Toxina Tetânica/genética
9.
Mol Cell Biol ; 18(5): 2804-14, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9566899

RESUMO

Active transcriptional repression has been characterized as a function of many regulatory factors. It facilitates combinatorial regulation of gene expression by allowing repressors to be dominant over activators under certain conditions. Here, we show that the Engrailed protein uses two distinct mechanisms to repress transcription. One activity is predominant under normal transient transfection assay conditions in cultured cells. A second activity is predominant in an in vivo active repression assay. The domain mediating the in vivo activity (eh1) is highly conserved throughout several classes of homeoproteins and interacts specifically with the Groucho corepressor. While eh1 shows only weak activity in transient transfections, much stronger activity is seen in culture when an integrated target gene is used. In this assay, the relative activities of different repression domains closely parallel those seen in vivo, with eh1 showing the predominant activity. Reducing the amounts of repressor and target gene in a transient transfection assay also increases the sensitivity of the assay to the Groucho interaction domain, albeit to a lesser extent. This suggests that it utilizes rate-limiting components that are relatively low in abundance. Since Groucho itself is abundant in these cells, the results suggest that a limiting component is recruited effectively by the repressor-corepressor complex only on integrated target genes.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Genes de Insetos , Proteínas de Homeodomínio/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição , Sequência de Aminoácidos , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Células Cultivadas , Sequência Conservada , Análise Mutacional de DNA , Proteínas de Ligação a DNA/genética , Drosophila/citologia , Proteínas de Homeodomínio/genética , Fragmentos de Peptídeos , Ligação Proteica , Proteínas Repressoras/genética , Deleção de Sequência , Transfecção
10.
Mol Cell Biol ; 19(7): 5189-202, 1999 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10373568

RESUMO

In Drosophila, two classes of genes, the trithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within the bxd/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX binding in vivo. TRX was localized to three closely situated sites within a 3-kb chromatin maintenance unit with a modular structure. Results of an in vivo analysis showed that these DNA fragments (each approximately 400 bp) contain both TRX- and Polycomb-group response elements (TREs and PREs) and that in the context of the endogenous Ultrabithorax gene, all of these elements are essential for proper maintenance of expression in embryos. Dissection of one of these maintenance modules showed that TRX- and Polycomb-group responsiveness is conferred by neighboring but separable DNA sequences, suggesting that independent protein complexes are formed at their respective response elements. Furthermore, we have found that the activity of this TRE requires a sequence (approximately 90 bp) which maps to within several tens of base pairs from the closest neighboring PRE and that the PRE activity in one of the elements may require a binding site for PHO, the protein product of the Polycomb-group gene pleiohomeotic. Our results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators.


Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila , Proteínas de Homeodomínio/genética , Proteínas de Insetos/metabolismo , Elementos de Resposta , Fatores de Transcrição , Transcrição Gênica , Animais , Sítios de Ligação , Mapeamento Cromossômico , Drosophila/embriologia , Drosophila/genética , Complexo Repressor Polycomb 1
11.
J Chromatogr A ; 1146(1): 61-6, 2007 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-17306277

RESUMO

A simple and sensitive method for the determination of abietic acid and dehydroabietic acid in food samples was developed using a fully automated method consisting of in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-mass spectrometry (LC/MS). These compounds were separated within 5min by HPLC using an ODS-3 column and 5mM ammonium formate/acetonitrile (10/90, v/v). Electrospray ionization conditions in the negative ion mode were optimized for MS detection of abietic acid and dehydroabietic acid. The optimum in-tube SPME conditions were 20draw/eject cycles of 40microL of sample using a Supel Q PLOT capillary column as an extraction device. The extracted compounds were easily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME LC/MS method, good linearity of the calibration curve (r>0.9998) was obtained in the concentration range from 0 to 50ng/mL, and the detection limits (S/N=3) of abietic acid and dehydroabietic acid were 2.9 and 2.1pg/mL, respectively. The in-tube SPME method showed above 75-fold greater sensitivity than the direct injection method (5microL injection). This method was applied successfully to analysis of food samples without interference peaks. The recoveries of abietic acid and dehydroabietic acid spiked into liquid samples were above 79%, and the relative standard deviations were below 6.6%. These compounds were detected at ng/mL or ng/g levels in various liquid or solid food samples contacted with paper.


Assuntos
Abietanos/análise , Cromatografia Líquida/métodos , Análise de Alimentos/métodos , Espectrometria de Massas/métodos , Fenantrenos/análise , Microextração em Fase Sólida/métodos , Bebidas/análise , Calibragem , Cromatografia Líquida/instrumentação , Análise de Alimentos/instrumentação , Espectrometria de Massas/instrumentação , Reprodutibilidade dos Testes , Microextração em Fase Sólida/instrumentação , Chá/química , Vinho/análise
12.
Clin Exp Rheumatol ; 24(5): 546-54, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17181924

RESUMO

OBJECTIVE: Methotrexate (MTX) is most widely used for the treatment of rheumatoid arthritis (RA). However, it has certain drawbacks with regard to individual differences in its therapeutic effects as well as the differences in the patients' response to MTX therapy. We investigated whether multi-drug resistance-1 (ABCB1) C3435T, reduced folate carrier-1 (RFC1) G80A, 5-aminoimidazole-4-carboxamide ribonucleotide transformylase (ATIC) C347G and a 6bp-deletion polymorphism in the 3'-untranslated region of the thymidylase synthase (TYMS) gene are predictive of MTX sensitivity and its adverse effects. METHODS: Patients whose last maintenance dosage of MTX was 6 mg/week or those in whom MTX therapy was changed due to poor response to MTX were regarded as non-responders. The data of 124 RA patients who had received MTX treatment were retrospectively analyzed for polymorphisms in the ABCB1, RFC1, ATIC and TYMS genes, MTX sensitivity and MTX toxicity. RESULTS: There were no significant differences in MTX sensitivity among the genotypes of RFC1, ATIC and TYMS genes. ABCB1 3435TT cases included statistically significantly more non-responders than 3435CC cases according to univariate analysis (crude odds ratio (OR) = 8.91, p = 0.001) and multivariate analysis (adjusted OR = 8.78, p = 0.038). There were no significant differences in MTX toxicity among the genotypes of all the genes. CONCLUSION: These results suggested that the genetic diagnosis of ABCB1 C3435T can be applied to determine MTX sensitivity for the treatment of RA patients. However, further pharmacokinetics studies are required in this regard.


Assuntos
Antirreumáticos/uso terapêutico , Artrite Reumatoide/tratamento farmacológico , Resistência a Múltiplos Medicamentos/genética , Metotrexato/uso terapêutico , Transportadores de Ânions Orgânicos/genética , Polimorfismo Genético , Subfamília B de Transportador de Cassetes de Ligação de ATP , Membro 1 da Subfamília B de Cassetes de Ligação de ATP , Antirreumáticos/efeitos adversos , Artrite Reumatoide/genética , Artrite Reumatoide/fisiopatologia , Feminino , Genótipo , Nível de Saúde , Humanos , Hidroximetil e Formil Transferases/genética , Articulações/fisiopatologia , Masculino , Proteínas de Membrana Transportadoras/genética , Metotrexato/efeitos adversos , Pessoa de Meia-Idade , Complexos Multienzimáticos/genética , Nucleotídeo Desaminases/genética , Estudos Retrospectivos , Índice de Gravidade de Doença , Timidilato Sintase/genética , Resultado do Tratamento
13.
Rev Sci Instrum ; 87(7): 076103, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27475610

RESUMO

A novel diamond anvil cell suitable for electrical transport measurements under high pressure has been developed. A boron-doped metallic diamond film was deposited as an electrode on a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The maximum pressure that can be achieved by this assembly is above 30 GPa. We report electrical transport measurements of Pb up to 8 GPa. The boron-doped metallic diamond electrodes showed no signs of degradation after repeated compression.

14.
Biochim Biophys Acta ; 570(1): 210-2, 1979 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-226150

RESUMO

The stereospecificity of hydrogen transfer in the synthesis of saccharopine from alpha-ketoglutarate and L-lysine catalyzed by saccharopine dehydrogenase (N5-(1,3-dicarboxypropyl)-L-lysine: NAD oxidoreductase (L-lysine-forming), EC 1.5.1.7) was examined by using [4A-3H]- and [4B-3H]NADH. The enzyme showed the A-stereospecificity. The NMR analysis of the saccharopine prepared with [4"A-2H]NADH revealed that the label was incorporated into the C-2 of the glutaryl moiety.


Assuntos
Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Sacaropina Desidrogenases/metabolismo , Hidrogênio/metabolismo , Espectroscopia de Ressonância Magnética , NAD/metabolismo , Estereoisomerismo
15.
Biochim Biophys Acta ; 785(3): 177-80, 1984 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-6608376

RESUMO

The spectral changes observed on interaction of S-adenosylhomocysteinase with adenine and cordycepin are approximated by the addition of dimethylsulfoxide to the aqueous solutions of these compounds, but not by protonation of the compounds. Although adenosine when bound to the enzyme undergoes partial reactions, it gives a spectral change similar to those obtained with adenine and cordycepin, except for the occurrence of a peak at 327 nm due to the reduction of the enzyme-bound NAD. From these results, it is suggested that S-adenosylhomocysteinase binds the nucleoside substrates mainly through hydrophobic interactions.


Assuntos
Adenina/metabolismo , Adenosina/metabolismo , Desoxiadenosinas/metabolismo , Hidrolases/metabolismo , Adenosil-Homocisteinase , Animais , Ligação Competitiva , Dimetil Sulfóxido/farmacologia , Fígado/enzimologia , NAD/metabolismo , Ligação Proteica , Ratos , Espectrofotometria , Espectrofotometria Ultravioleta
16.
Biochim Biophys Acta ; 996(1-2): 139-41, 1989 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-2660911

RESUMO

The blocked amino-terminal residue of rat liver serine dehydratase was shown to be acetylalanine by analysis of an isolated amino-terminal peptide after digestion with acylamino acid-releasing enzyme. Digestion of the borohydride-reduced, carboxymethylated enzyme with lysyl endopeptidase yielded a single epsilon-N-pyridoxyllysine-containing peptide, whose sequence is Met-Asp-Ser-Ser-Gln-Pro-Ser-Gly-Ser-Phe-Lys(Pxy)-Ile-Arg-Gly- His-Leu-Cys(Cm)-Lys. This peptide comprises residues 30-49 of the cDNA-deduced amino acid sequence. The sequence of seven amino acids around the bound pyridoxal phosphate is highly conserved in serine dehydratase from rat liver, and threonine dehydratases from yeast and Escherichia coli.


Assuntos
L-Serina Desidratase/análise , Fosfato de Piridoxal , Treonina Desidratase/análise , Sequência de Aminoácidos , Animais , Sítios de Ligação , Cromatografia Líquida de Alta Pressão , Escherichia coli/enzimologia , Fígado/enzimologia , Dados de Sequência Molecular , Fragmentos de Peptídeos/análise , Ratos , Saccharomyces cerevisiae/enzimologia
17.
Biochim Biophys Acta ; 623(1): 225-8, 1980 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-6769500

RESUMO

The yeast saccharopine dehydrogenase (L-lysine-forming) contains an essential cysteine residue at the active site which can be carboxymethylated selectively by iodoacetate (Ogawa, H., Okamoto, M. and Fujioka, M. (1979) J. Biol. Chem. 254, 7030--7035). An undecapeptide containing this residue was isolated from the chymotryptic digest of the carboxymethylated enzyme by gel filtration chromatography and preparative paper electrophoresis. The amino acid sequence of the peptide was determined as Gly-Arg-Cys*-Gly-Ser-Gly-Ala-Leu-Ile-Asp-Leu, by the sequential Edman degradation and digestion with carboxypeptidases.


Assuntos
Cisteína/análise , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Saccharomyces cerevisiae/enzimologia , Sacaropina Desidrogenases/metabolismo , Sequência de Aminoácidos , Lisina/metabolismo , Fragmentos de Peptídeos/isolamento & purificação
18.
Biochim Biophys Acta ; 994(2): 172-9, 1989 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-2910349

RESUMO

Rat liver S-adenosylhomocysteinase, a homotetramer, was resolved by treatment with acid ammonium sulfate into apoenzyme and NAD. The apoenzyme thus prepared retained a tetrameric structure but differed in the mobility on nondenaturing polyacrylamide gel electrophoresis. The inactive apoenzyme was reactivated upon incubation with NAD. The restoration of activity paralleled with the tight binding of NAD to apoenzyme, and full activity was obtained when 4 mol of NAD were bound per mol of apoenzyme. The kinetics of reconstitution were apparently biphasic and suggest the existence of two conformers in a slow equilibrium, one of which binds the coenzyme rapidly while the other does so very slowly, if at all. In addition to NAD, apoadenosylhomocysteinase tightly bound nicotinamide hypoxanthine dinucleotide, 3-acetylpyridine adenine dinucleotide and nicotinic acid-adenine dinucleotide. NADP was not bound. Catalytic activity was found only with the enzyme reconstituted with NAD or nicotinamide hypoxanthine dinucleotide. The spectral change observed on interaction of apoadenosylhomocysteinase with NAD was similar to those seen with adenine nucleotides, and was largely approximated by the addition of dioxane to aqueous solutions of adenine nucleotides. By comparison of the difference spectra, it is suggested that the adenine portion of the coenzyme is bound in the hydrophobic pocket of the protein, and that the binding is accompanied by perturbation of tryptophan residue of the protein.


Assuntos
Hidrolases/metabolismo , Fígado/enzimologia , NAD/metabolismo , Adenosil-Homocisteinase , Animais , Apoproteínas/metabolismo , Dicroísmo Circular , Hidrolases/isolamento & purificação , Cinética , NAD/análogos & derivados , Ratos , Espectrofotometria Ultravioleta , Relação Estrutura-Atividade
19.
J Mol Biol ; 298(1): 149-62, 2000 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-10756111

RESUMO

Glycine N-methyltransferase (S-adenosyl-l-methionine: glycine methyltransferase, EC 2.1.1.20; GNMT) catalyzes the AdoMet-dependent methylation of glycine to form sarcosine (N-methylglycine). Unlike most methyltransferases, GNMT is a tetrameric protein showing a positive cooperativity in AdoMet binding and weak inhibition by S-adenosylhomocysteine (AdoHcy). The first crystal structure of GNMT complexed with AdoMet showed a unique "closed" molecular basket structure, in which the N-terminal section penetrates and corks the entrance of the adjacent subunit. Thus, the apparent entrance or exit of the active site is not recognizable in the subunit structure, suggesting that the enzyme must possess a second, enzymatically active, "open" structural conformation. A new crystalline form of the R175K enzyme has been grown in the presence of an excess of AdoHcy, and its crystal structure has been determined at 3.0 A resolution. In this structure, the N-terminal domain (40 amino acid residues) of each subunit has moved out of the active site of the adjacent subunit, and the entrances of the active sites are now opened widely. An AdoHcy molecule has entered the site occupied in the "closed" structure by Glu15 and Gly16 of the N-terminal domain of the adjacent subunit. An AdoHcy binds to the consensus AdoMet binding site observed in the other methyltransferase. This AdoHcy binding site supports the glycine binding site (Arg175) deduced from a chemical modification study and site-directed mutagenesis (R175K). The crystal structures of WT and R175K enzymes were also determined at 2.5 A resolution. These enzyme structures have a closed molecular basket structure and are isomorphous to the previously determined AdoMet-GNMT structure. By comparing the open structure to the closed structure, mechanisms for auto-inhibition and for the forced release of the product AdoHcy have been revealed in the GNMT structure. The N-terminal section of the adjacent subunit occupies the AdoMet binding site and thus inhibits the methyltransfer reaction, whereas the same N-terminal section forces the departure of the potentially potent inhibitor AdoHcy from the active site and thus facilitates the methyltransfer reaction. Consequently GNMT is less active at a low level of AdoMet concentration, and is only weakly inhibited by AdoHcy. These properties of GNMT are particularly suited for regulation of the cellular AdoMet/AdoHcy ratio.


Assuntos
Metiltransferases/antagonistas & inibidores , Metiltransferases/química , Mutação/genética , S-Adenosil-Homocisteína/metabolismo , Regulação Alostérica , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Sítios de Ligação , Catálise , Sequência Consenso , Cristalografia por Raios X , Glicina/metabolismo , Glicina N-Metiltransferase , Cinética , Metilação , Metiltransferases/genética , Metiltransferases/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , S-Adenosil-Homocisteína/química , S-Adenosilmetionina/metabolismo , Relação Estrutura-Atividade
20.
Mech Dev ; 73(2): 169-82, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9622621

RESUMO

In this study we investigate the gene regulatory functions of Drosophila Fish-hook (Fish), a high mobility group (HMG) Sox protein that is essential for embryonic segmentation. We show that the Fish HMG domain binds to the vertebrate Sox protein consensus DNA binding sites, AACAAT and AACAAAG, and that this binding induces an 85 degrees DNA bend. In addition, we use a heterologous yeast system to show that the NH2-terminal portion of Fish protein can function as a transcriptional activator. Fish directly regulates the expression of the pair rule gene, even-skipped (eve), by binding to multiple sites located in downstream regulatory regions that direct formation of eve stripes 1, 4, 5, and 6. Fish may function along with the Drosophila POU domain proteins Pdm-1 and Pdm-2 to regulate eve transcription, as genetic interactions were detected between fish and pdm mutants. Finally, we determined that Fish protein is expressed in a dynamic pattern throughout embryogenesis, and is present in nuclear and cytoplasmic compartments.


Assuntos
Proteínas de Ligação a DNA/fisiologia , Proteínas de Drosophila , Drosophila/genética , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Proteínas de Grupo de Alta Mobilidade/fisiologia , Fatores de Transcrição/fisiologia , Animais , Sequência de Bases , Primers do DNA , Drosophila/embriologia , Fatores de Transcrição SOX , Ativação Transcricional/fisiologia
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