RESUMEN
OBJECTIVE: To investigate the oil body protein and function in seeds of mature seagrass, Thalassia hemprichii. RESULTS: Seeds of mature seagrass T. hemprichii when stained with a fluorescent probe BODIPY showed the presence of oil bodies in intracellular cells. Triacylglycerol was the major lipid class in the seeds. Protein extracted from seagrass seeds was subjected to immunological cross-recognition with land plant seed oil body proteins, such as oleosin and caleosin, resulting in no cross-reactivity. An oleosin-like gene was found in seagrass seeds. Next generation sequencing and sequence alignment indicated that the deduced seagrass seed oleosin-like protein has a central hydrophobic domain responsible for their anchoring onto the surface of oil bodies. Phylogenetic analysis showed that the oleosin-like protein was evolutionarily closer to pollen oleosin than to seed oleosins. CONCLUSION: Oil body protein found in seagrass seeds represent a distinct class of land seed oil body proteins.
Asunto(s)
Hydrocharitaceae/embriología , Gotas Lipídicas/metabolismo , Proteínas de Plantas/genética , Semillas/genética , Clonación Molecular , Secuenciación de Nucleótidos de Alto Rendimiento , Hydrocharitaceae/genética , Hydrocharitaceae/metabolismo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Dominios Proteicos , Semillas/metabolismo , Alineación de Secuencia , Análisis de Secuencia de ADN , Triglicéridos/metabolismoRESUMEN
Strong hard (ε>100 keV) x rays being observed from impulse atmospheric discharges with maximal voltages from U=0.5 to 0.9 MV just before the breakdown were completely stopped with the use of femtosecond-laser-filament plasma. Runaway electrons generating such x rays and being estimated to achieve their maximal energy, ε~U, near the positive electrode disappear if a laser filament plasma is ignited perpendicularly to the runaway near the positive electrode. A preheating mechanism for formation of the electron runaway in air is proposed.
RESUMEN
Wegener's granulomatosis (WG) is characterized by systemic granulomatous necrotizing vasculitis, primarily affecting the respiratory tract and kidneys. We describe a rare case in a 28-year-old woman with WG, presenting with a massive lateral pleural effusion, accompanied by an aseptic bronchopleural fistula formed during immunosuppressive treatment. Although any organ can be involved in WG, only left pleuritis and a purpuric lesion on the neck were detected in this case. The pleural effusion and bronchopleural fistula resolved following immunosuppressive treatment for six months. Thus, WG should be considered in the differential diagnosis of a massive pleural effusion, and fistula formation is a possible complication of treatment. Moreover, immunosuppressive treatment was sufficient to resolve the massive pleural effusion and fistula formation without infection (120 words).
Asunto(s)
Fístula Bronquial/etiología , Granulomatosis con Poliangitis/diagnóstico , Enfermedades Pleurales/etiología , Derrame Pleural/etiología , Fístula del Sistema Respiratorio/etiología , Adulto , Biopsia , Fístula Bronquial/diagnóstico , Fístula Bronquial/tratamiento farmacológico , Femenino , Granulomatosis con Poliangitis/complicaciones , Granulomatosis con Poliangitis/tratamiento farmacológico , Humanos , Inmunosupresores/administración & dosificación , Inmunosupresores/efectos adversos , Enfermedades Pleurales/diagnóstico , Enfermedades Pleurales/tratamiento farmacológico , Derrame Pleural/diagnóstico , Derrame Pleural/tratamiento farmacológico , Tomografía de Emisión de Positrones , Fístula del Sistema Respiratorio/diagnóstico , Fístula del Sistema Respiratorio/tratamiento farmacológico , Piel/patología , Tomografía Computarizada por Rayos X , Resultado del TratamientoRESUMEN
Femtosecond laser pulses were used to make plasma filaments near an isolated positively or negatively highly biased electrode. The electrode was well positioned to sustain a high voltage up to U(max)=+/-400 kV to avoid the induced breakdown or a glow discharge; the shape of the electrode was chosen to reduce the corona effects at the maximal voltage. The filament's UV emission is shown to be very sensitive to the voltage applied: it increases nonlinearly with the electrode potential. Along with nanosecond filament-induced flashes at both polarities, long, about a half microsecond, corona flashes were observed at the negative polarity.
RESUMEN
OBJECTIVE: Severe congenital neutropenia (SCN), also known as Kostmann syndrome (SCN3, OMIM 610738), includes a variety of haematological disorders caused by different genetic abnormalities. Mutations in ELA2 are most often the cause in autosomal dominant or sporadic forms. Recently, mutations in HAX1 have been identified as the cause of some autosomal recessive forms of SCN, including those present in the original pedigree first reported by Kostmann. We sought to determine the relationship between HAX1 gene mutations and the clinical characteristics of Japanese cases of SCN. METHODS: The genes implicated in SCN (ELA2, HAX1, Gfi-1, WAS, and P14) were analysed in 18 Japanese patients with SCN. The clinical features of these patients were obtained from medical records. Immunoblotting of HAX1 was performed on cell extracts from peripheral blood leucocytes from patients and/or their parents. RESULTS: We found five patients with HAX1 deficiency and 11 patients with mutations in the ELA2 gene. In HAX1 deficiency, a homozygous single base pair substitution (256C>T), which causes the nonsense change R86X, was identified in three affected individuals. Two sibling patients showed a compound heterozygous mutation consisting of a single base pair substitution (256C>T) and a 59 bp deletion at nucleotides 376-434. There was no detectable phenotype in any heterozygous carrier. All patients with HAX1 deficiency had experienced developmental delay. Three patients carrying R86X also suffered from epileptic seizures. In contrast, no SCN patient with heterozygous mutations in the ELA2 gene suffered from any neurodevelopmental abnormality. CONCLUSIONS: These findings suggest that the R86X mutation in the HAX1 gene is an abnormality in Japanese SCN patients with HAX1 deficiency and may lead to neurodevelopmental abnormalities and severe myelopoietic defects.
Asunto(s)
Discapacidades del Desarrollo/genética , Mutación , Neutropenia/congénito , Neutropenia/genética , Proteínas/genética , Proteínas Adaptadoras Transductoras de Señales , Secuencia de Bases , Femenino , Homocigoto , Humanos , Lactante , Masculino , Datos de Secuencia Molecular , LinajeRESUMEN
We sequenced the major histocompatibility complex (MHC) class II DQA1 gene in 352 Japanese cattle (95 Japanese Black, 91 Holstein, 102 Japanese Shorthorn and 64 Jersey cattle) using a new sequence-based typing method. In total, 19 bovine MHC (BoLA)-DQA1 alleles, of which two were novel alleles, were detected. The Holstein, Jersey, Japanese Shorthorn and Japanese Black breeds had 13, 12, 10 and 15 alleles, respectively. The dendrogram that was constructed by the neighbor-joining method on the basis of the DQA1 gene allele frequencies of the four Japanese cattle breeds showed that the Holstein and Japanese Black breeds were closest to each other, with Jersey being farther from these two breeds than Japanese Shorthorn. In addition, Wu-Kabat analysis showed that the DQA1 alleles of the Holstein and Japanese Black were the most and least polymorphic, respectively. Phylogenetic analyses indicated that the DQA1 gene of Bovidae such as cattle, sheep, bison and goat were more similar to pig SLA-DQA genes than to human HLA-DQA1 and dog DLA-DQA genes. The cattle, goat, bison, sheep, human and pig DQA1 molecules had similar rates of amino acid sequence polymorphism, but the distribution of their polymorphic residues differed from that in the dog DQA1 protein. However, the Bovidae DQA1 molecule had more polymorphic residues than the human, pig and dog DQA molecules at two regions, namely positions 52-53 and 65-66. This indicates that the Bovidae DQA1 locus is more polymorphic than the DQA loci of other species.
Asunto(s)
Genes MHC Clase II , Antígenos de Histocompatibilidad Clase II/genética , Alelos , Animales , Secuencia de Bases , Cruzamiento , Bovinos , Perros , Variación Genética , Humanos , Japón , Datos de Secuencia Molecular , Filogenia , Polimorfismo Genético , Especificidad de la EspecieRESUMEN
OBJECTIVE: To develop a population pharmacokinetic model for biapenem in paediatric patients and to use the parameter estimates to assess pharmacodynamic exposure of common bacterial populations. METHODS: Biapenem plasma concentrations (n = 125) from 25 paediatric patients were analysed using nonmem. The parameter estimates were used in a Monte Carlo simulation to predict the exposure time during which the drug concentration remains above the minimum inhibitory concentration. RESULTS: A two-compartment model fitted the data, and creatinine clearance (CL(cr)) and total body weight (TBW) were the most significant covariates. The final model was CL (L/h) = 0.0458 x CL(cr), V(c) (L) = 0.162 x TBW, Q (L/h) = 2.05, V(p) (L) = 1.73, where CL is the clearance, V(c) is the volume of distribution of the central compartment, Q is the intercompartmental clearance and V(p) is the volume of distribution of the peripheral compartment. Biapenem regimens of 5 mg/kg q8h and 10 mg/kg q8h provided sufficient pharmacodynamic exposures to Pseudomonas aeruginosa and Streptococcus pneumoniae in most typical patient populations. CONCLUSION: These results better define the pharmacokinetics of biapenem and help in the choice of the appropriate dosage regimens for paediatric.
Asunto(s)
Antibacterianos/farmacocinética , Modelos Biológicos , Tienamicinas/farmacocinética , Adolescente , Antibacterianos/sangre , Antibacterianos/farmacología , Infecciones Bacterianas/sangre , Infecciones Bacterianas/tratamiento farmacológico , Peso Corporal , Niño , Preescolar , Creatinina/sangre , Femenino , Humanos , Lactante , Masculino , Pruebas de Sensibilidad Microbiana , Método de Montecarlo , Pseudomonas aeruginosa/efectos de los fármacos , Streptococcus pneumoniae/efectos de los fármacos , Tienamicinas/sangre , Tienamicinas/farmacologíaRESUMEN
Attentional mechanisms are important for selecting relevant information and filtering out irrelevant information from cluttered visual scenes. Selective attention has previously been shown to affect neural activity in both extrastriate and striate visual cortex. Here, evidence from functional brain imaging shows that attentional response modulation is not confined to cortical processing, but can occur as early as the thalamic level. We found that attention modulated neural activity in the human lateral geniculate nucleus (LGN) in several ways: it enhanced neural responses to attended stimuli, attenuated responses to ignored stimuli and increased baseline activity in the absence of visual stimulation. The LGN, traditionally viewed as the gateway to visual cortex, may also serve as a 'gatekeeper' in controlling attentional response gain.
Asunto(s)
Atención/fisiología , Cuerpos Geniculados/fisiología , Percepción Espacial/fisiología , Adulto , Movimientos Oculares/fisiología , Femenino , Fijación Ocular/fisiología , Humanos , Masculino , Estimulación Luminosa , Corteza Visual/fisiologíaRESUMEN
Local production of immunosuppressive cytokines will be one of the most suitable therapeutic strategies against organ-specific autoimmune diabetes. To establish such a new therapy, we constructed recombinant adenoviral vectors with inserted mIL-12p40 (Ad.IL-12p40) and mIL-10 (Ad.IL-10). Sufficient amounts of IL-12p40 and IL-10 were secreted by relevant adenovirus-transfected nonobese diabetic (NOD) islets. Shortly after transfection, 400 NOD islets transfected with Ad.IL-12p40 or Ad.IL-10 were transplanted under the renal capsule of a newly diabetic NOD mouse. NOD mice with IL-12p40-producing islet grafts kept normoglycemia in all of 14 grafted mice for over 4 wk after transplantation. In contrast, NOD mice with IL-10-producing islet grafts became diabetic in all of six grafted mice within 2 wk af-ter transplantation. Reverse transcription-PCR analysis revealed that local production of IL-12p40 led to the decrease of interferon-gamma and the augmentation of transforming growth factor-beta at the graft site. These results suggest that IL-12 plays an important role in the destruction of islet cells at the inflamed site of autoimmunity. Such a local blockade of IL-12 would be a useful gene therapy for human autoimmune diabetes.
Asunto(s)
Supervivencia de Injerto , Interleucina-12/metabolismo , Trasplante de Islotes Pancreáticos , Adenoviridae , Animales , Diabetes Mellitus Tipo 1/prevención & control , Femenino , Citometría de Flujo , Vectores Genéticos , Supervivencia de Injerto/inmunología , Insulina/metabolismo , Interleucina-10/metabolismo , Interleucina-12/genética , Islotes Pancreáticos/metabolismo , Trasplante de Islotes Pancreáticos/inmunología , Riñón/cirugía , Leucocitos Mononucleares/citología , Masculino , Ratones , Ratones Endogámicos NODRESUMEN
HAX1 deficiency has recently been identified as a cause of severe congenital neutropenia (SCN), but little is known about the phenotype. We described an SCN patient with a homozygous 256C-to-T transition causing an R86X mutation in the HAX1 gene. Notably, the patient has been complicated by epilepsy and severe delay of motor, cognitive, and intellectual development; each developmental quotient was 21-26 at 7 years old. Growth failure and dental development delay were also noted. Neurodevelopmental delay in this patient expands the clinical phenotype of HAX1 deficiency and suggests an important role of HAX1 on neural development as well as myelopoiesis.
Asunto(s)
Discapacidades del Desarrollo/genética , Epilepsia/congénito , Mielopoyesis/genética , Neutropenia/congénito , Mutación Puntual , Proteínas/genética , Proteínas Adaptadoras Transductoras de Señales , Pueblo Asiatico , Niño , Humanos , Japón , Masculino , FenotipoRESUMEN
BACKGROUND: The incidence and mortality from gastric cancer is high in Japanese but extremely low in Thailand. It is different among Asian countries. The aim of this study is to investigate the difference of peptic ulcer disease, glandular atrophy, intestinal metaplasia and topography of chronic active gastritis between the Nepalese and Japanese population. MATERIALS AND METHODS: Nepalese patients were paired with Japanese patients by age, gender and endoscopic diagnosis in order to compare the prevalence of H. pylori infection (N=309) and the difference of H. pylori related peptic ulcer disease (N=48). Glandular atrophy and intestinal metaplasia scores were also compared between the Nepalese and Japanese population in H. pylori positive cases (N=152) and negative cases (N=145) using paired cases by age, gender and endoscopic diagnosis. Paired H. pylori-positive Nepalese and Japanese population were also used to compare the ratio of corpus gastritis to antrum gastritis (C/A ratio) (N=152). RESULTS: Among peptic ulcer diseases, gastric ulcer was frequent in Japanese and duodenal ulcer was frequent in Nepalese. The prevalence of H. pylori infection in the Nepalese and Japanese population were similar. Glandular atrophy and intestinal metaplasia scores in the H. pylori positive Japanese were significantly higher than those of Nepalese in all positions according to triple site biopsy. Furthermore, there were significant differences in glandular atrophy and intestinal metaplasia scores between in the H. pylori-negative Nepalese and Japanese population except intestinal metaplasia score in the greater curvature of the upper corpus. Japanese C/A ratio was significantly higher than that of Nepalese. Corpus predominant gastritis (C/A ratio>1.00) was characteristic in the elderly Japanese. Nepalese was antrum predominant (C/A ratio<1.00) in every age group. CONCLUSIONS: Gastric ulcer was a common disease in Japanese, in contrast duodenal ulcer was common in Nepalese. H. pylori infected Japanese patients showed severe atrophic and metaplastic gastritis in comparison with Nepalese. These results may be associated with the high incidence of gastric cancer in Japanese. Corpus predominant gastritis was found in the elderly Japanese and antrum predominant gastritis was found in every age Nepalese.
Asunto(s)
Gastritis/epidemiología , Infecciones por Helicobacter/epidemiología , Helicobacter pylori , Úlcera Péptica/epidemiología , Adulto , Anciano , Atrofia , Femenino , Mucosa Gástrica/patología , Gastritis/microbiología , Gastritis/patología , Gastroscopía , Infecciones por Helicobacter/patología , Humanos , Japón/epidemiología , Masculino , Metaplasia/microbiología , Metaplasia/patología , Persona de Mediana Edad , Nepal/epidemiología , Úlcera Péptica/microbiología , Úlcera Péptica/patología , Prevalencia , Estadísticas no ParamétricasRESUMEN
BACKGROUND: The absorption and bioavailability of proton pump inhibitors is influenced by food intake. Proton pump inhibitors bind to the parietal cell active proton pump, which is maximally stimulated after dinner: usually the largest meal of the day. However, it has not been fully clarified whether the efficacy of proton pump inhibitors differs between post-breakfast and pre-dinner dosing. AIM: To perform a pH-monitoring study to clarify this issue for two low-dose proton pump inhibitors. SUBJECTS AND METHODS: The subjects were 20 healthy male volunteers (seven Helicobacter pylori-positive and 13 H. pylori-negative), who were divided into two groups of 10 and administered 15 mg lansoprazole or 10 mg rabeprazole, respectively. All subjects underwent ambulatory intragastric 24-h pH- monitoring under three conditions allocated randomly: (i) without medication, (ii) seventh day of post-breakfast administration and (iii) eighth day of pre-dinner administration of each drug. RESULTS: There was no significant difference in the percentage time during which pH > or =4.0 in the 24-h period between post-breakfast and pre-dinner administration of both drugs (56.6% vs. 55.8%; P = 0.557), although intragastric acidity during administration of both drugs was significantly lower than that without medication. CONCLUSIONS: The timing of drug administration does not significantly influence the efficacy of low-dose proton pump inhibitors.
Asunto(s)
2-Piridinilmetilsulfinilbencimidazoles/administración & dosificación , Jugo Gástrico/metabolismo , Inhibidores de la Bomba de Protones , Adulto , Antiulcerosos/administración & dosificación , Estudios Cruzados , Esquema de Medicación , Determinación de la Acidez Gástrica , Infecciones por Helicobacter/metabolismo , Helicobacter pylori , Humanos , Concentración de Iones de Hidrógeno/efectos de los fármacos , Lansoprazol , Masculino , Persona de Mediana Edad , Bombas de Protones/administración & dosificación , Rabeprazol , Factores de TiempoRESUMEN
SETTING: The polymerase chain reaction (PCR) is a highly sensitive method for the detection of Mycobacterium tuberculosis and is available in most countries, though to a lesser extent in rural areas. OBJECTIVE: To amplify M. tuberculosis DNA sequences of sputum spotted on FTA cards and compare them with the results of microscopic examination among culture-positive samples. DESIGN: A total of 102 sputum specimens of TB patients in treatment were spotted on FTA cards and stored at room temperature until DNA analysis. We assessed the IS6110 region of M. tuberculosis. The efficacy of the PCR assay for the direct detection of M. tuberculosis was evaluated and compared with the results of cultures (Middlebrook 7H9 broth) and smears of fresh sputum specimens. RESULTS: We were able to detect 10 fg/microl of mycobacterial DNA even after 6 months in storage. The PCR sensitivity and specificity using the FTA card system were 82% and 96%, while microscopic examination showed 41% and 95%, respectively. CONCLUSION: The FTA card system for the storage of bacterial DNA from sputum samples should be considered for the molecular diagnosis of tuberculosis. Samples can easily be obtained from geographically isolated populations and shipped by mail for accurate molecular diagnosis.
Asunto(s)
Mycobacterium tuberculosis/aislamiento & purificación , Manejo de Especímenes , Esputo/microbiología , Tuberculosis/diagnóstico , Técnicas Bacteriológicas/normas , ADN Bacteriano/aislamiento & purificación , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/genética , Reacción en Cadena de la Polimerasa , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Manejo de Especímenes/normas , Tuberculosis/microbiologíaRESUMEN
Sesame (Sesamum indicum L.) seed has been recognized as a nutritional protein source owing to its richness in methionine. Storage proteins have been implicated in allergenic responses to sesame consumption. Two abundant storage proteins, 11S globulin and 2S albumin, constitute 60-70 and 15-25% of total sesame proteins, respectively. Two gene families separately encoding four 11S globulin and three 2S albumin isoforms were identified in a database search of 3328 expressed sequence tag (EST) sequences from maturing sesame seeds. Full-length cDNA sequences derived from these two gene families were completed by PCR using a maturing sesame cDNA library as the template. The amino acid compositions of these deduced storage proteins revealed that the richness in methionine is attributed mainly to two 2S albumin isoforms and partly to one 11S globulin isoform. The presence of four 11S globulin and three 2S albumin isoforms resolved in SDS-PAGE was confirmed by MALDI-MS analyses. The abundance of these isoforms was in accord with the occurrence frequency of their EST sequences in the database. A comprehensive understanding of these storage proteins at the molecular level may also facilitate the identification of allergens in crude sesame products that have caused severe allergic reactions increasingly reported in the past decade.
Asunto(s)
Proteínas de Plantas/genética , Isoformas de Proteínas/genética , Semillas/química , Sesamum/química , Sesamum/genética , Albúminas/química , Albúminas/genética , Albúminas/aislamiento & purificación , Secuencia de Aminoácidos , ADN Complementario/química , ADN de Plantas/química , Biblioteca de Genes , Datos de Secuencia Molecular , Proteínas de Plantas/química , Reacción en Cadena de la Polimerasa , Isoformas de Proteínas/química , Alineación de SecuenciaRESUMEN
The interaction of troponin and F-actin was studied by the methods of fluorescence energy transfer. We used epsilon-ADP bound to F-actin as a fluorescence donor and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole bound to troponin-C in troponin as a fluorescence acceptor. The efficiency of the fluorescence energy transfer of this system was larger in the absence of calcium ion than in the presence of calcium ion. This shows that the interaction of troponin with F-actin changes in response to the concentration of calcium ion.
Asunto(s)
Actinas/metabolismo , Adenosina Difosfato/análogos & derivados , Proteínas Musculares/metabolismo , Troponina/metabolismo , 4-Cloro-7-nitrobenzofurazano , Adenosina Difosfato/metabolismo , Calcio/metabolismo , Transferencia de Energía , Conformación Proteica , Espectrometría de FluorescenciaRESUMEN
Fluorescence energy transfers were studied in order to investigate the spatial relationships between the nucleotide-binding site, the metal-binding site and the Cys-373 residue in the G-actin molecule. When 1-N6-ethenoadenosine-5'-triphosphate (epsilon-ATP) in the nucleotide-binding site and Co2+ or Ni2+ in the metal-binding site were used as fluorescence donor and acceptor, respectively, the fluorescence intensity of epsilon-ATP was perfectly quenched by Ni2+ or Co2+. This indicated that the nucleotide-binding site is very close to the metal-binding site; the distance should be less than 10 A. When N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine (IAEDANS) bound to Cys-373 residue and Co2+ in the metal-binding site were used as a fluorescence donor and an acceptor, respectively, the transfer efficiency was equal to 5 +/- 1%. The corresponding distance was calculated to be 23-32 A, assuming a random orientation factor K2 = 2/3.
Asunto(s)
Actinas/metabolismo , Adenosina Trifosfato/análogos & derivados , Cobalto/metabolismo , Cisteína , Etenoadenosina Trifosfato/metabolismo , Níquel/metabolismo , Animales , Sitios de Unión , Calcio/metabolismo , Cationes Bivalentes , Fenómenos Químicos , Química Física , Transferencia de Energía , Colorantes Fluorescentes , Naftalenosulfonatos/metabolismo , Conejos , Espectrometría de FluorescenciaRESUMEN
The method of fluorescence energy transfer is used to measure the distance from the nucleotide binding site to Cys-373 of G-actin. The fluorescent ATP analogue 1-N6-ethenoadenosine 5'-triphosphate was used as donor and N-(4-dimethylamino-3,5-dinitrophenyl)-maleimide was used as acceptor. From the measurements of the efficiency of fluorescence energy transfer by both static and time resolved fluorometries, the distance between nucleotide binding site and Cys-373 residue of G-actin was calculated to be about 30 A.
Asunto(s)
Actinas , Cisteína , Secuencia de Aminoácidos , Sitios de Unión , Transferencia de Energía , Etenoadenosina Trifosfato , Maleimidas , Conformación Proteica , Espectrometría de FluorescenciaRESUMEN
Intramonomer fluorescence energy transfer between the donor epsilon-ATP bound to the nucleotide-binding site and the acceptor 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole bound to Cys-373 in G-actin was measured by steady-state fluorimetry. Assuming for the orientation factor its dynamic limit K2 = 2/3, the donor and acceptor distance in a G-actin molecule was calculated to be about 3 nm. The intermonomer energy transfer in F-actin occurring between the donor bound to an actin monomer and the acceptor bound to the nearest-neighbour actin monomer was also measured and the distance was calculated to be about 4 nm. The kinetics of the actin polymerization process was studied by following the decrease in fluorescence intensity upon addition of salts to G-actin solution. The initial velocity of the fluorescence intensity change was proportional to the square of the initial G-actin concentration. The temperature dependence of the velocity was proportional to the square of the initial G-actin concentration. The temperature dependence of the velocity was proportional to exp(-10/RT). These results indicated that the initial fluorescence intensity change corresponds to monomer-dimer transformation and its activation enthalpy was 10 kcal/mol.
Asunto(s)
Actinas/metabolismo , 4-Cloro-7-nitrobenzofurazano , Adenosina Trifosfato/metabolismo , Animales , Sitios de Unión , Cisteína , Transferencia de Energía , Cinética , Polímeros , Conejos , Espectrometría de FluorescenciaRESUMEN
Fluorescence energy transfer was measured by time-resolved and steady-state fluorimetry in order to investigate the spatial relationships between the nucleotide binding site of actin, the Cys-373 residue of actin, and the SH1 of myosin subfragment-1 in the rigor complex of acto-subfragment-1. N-Iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine (IAEDANS) bound to the Cys-373 of actin or the fluorescent ADP analogue 1-N6-ethenoadenosine-5'-diphosphate (epsilon-ADP) bound to F-actin was used as a donor and 4-(N-(iodoacetoxy)ethyl-N-methyl)amino-7-nitrobenz-2-oxa-1,3-diazo le (IANBD) or 5-iodoacetamidofluorescein (IAF) bound to SH1 of myosin subfragment-1 was used as an acceptor. Assuming the random orientation factor, K2, to be 2/3, the distance between Cys-373 residue of actin and SH1 of myosin subfragment-1 was calculated to be about 50 A, in agreement with the values previously reported, 60 A (Takashi, R. (1969) Biochemistry 18, 5164-69) and 50 A (Trayer, H.R. and Trayer, I.P. (1983) Eur. J. Biochem. 135, 47-59). The distance between the nucleotide binding site of actin and SH1 of myosin subfragment-1 was calculated to be about 70 A or greater.
Asunto(s)
Actinas , Actomiosina , Contracción Muscular , Miosinas , Fragmentos de Péptidos , Adenosina Difosfato , Animales , Cisteína , Transferencia de Energía , Sustancias Macromoleculares , Subfragmentos de Miosina , Conformación Proteica , Conejos , Espectrometría de FluorescenciaRESUMEN
Intramonomer fluorescence resonance energy transfer between the donor epsilon-ATP bound to the nucleotide site and the acceptor N-(4-dimethylamino-3,5-dinitrophenyl)maleimide (DDPM) or 4-dimethylaminophenyl-azophenyl-4'-maleimide bound to Cys-10 in G-actin was measured. The donor-acceptor distance was calculated to be about 40 A. The intermonomer energy transfer in F-actin occurring between epsilon-ADP and DABMI was also measured. The radial coordinate of Cys-10 was calculated to be 25 A based on the helical symmetry of F-actin and the recently calculated radial coordinate of the nucleotide binding site in F-actin i.e. 25 A (Miki, M., Hambly, B. and dos Remedios, C.G. (1986) Biochim. Biophys. Acta 871, 137-141). (The assumption has been made in calculating these distances that the energy donor and acceptor rotate rapidly relative to the fluorescence lifetime.) Corresponding distances separating the donor nucleotide in one monomer from acceptors on Cys-10 in the first and second nearest neighbours in F-actin are 39-40 A and 41-43 A.