RESUMEN
The association of wind turbine noise (WTN) with sleep and physical/mental health has not been fully investigated. To investigate the relationship of WTN with the prevalence of self-reported symptoms of sleep and health problems, a socioacoustic survey of 1079 adult residents was conducted throughout Japan (2010-2012): 747 in 34 areas surrounding wind turbine plants and 332 in 16 control areas. During face-to-face interviews, the respondents were not informed of the purpose of the survey. Questions on symptoms such as sleeplessness and physical/mental complaints were asked without specifying reasons. Insomnia was defined as having one or any combination of the following that occurs three or more times a week and bothers a respondent: Difficulty initiating sleep, difficulty maintaining sleep, premature morning awakening, and feeling of light overnight sleep. Poor health was defined as having high scores for health complaints, as determined using the Total Health Index, exceeding the criteria proposed by the authors of the index. The noise descriptor for WTN was LAeq,n outdoor, estimated from the results of actual measurement at some locations in each site. Multiple logistic analysis was applied to the LAeq,n and insomnia or poor health. The odds ratio (OR) of insomnia was significantly higher when the noise exposure level exceeded 40 dB, whereas the self-reported sensitivity to noise and visual annoyance with wind turbines were also independently associated with insomnia. OR of poor health was not significant for noise exposure, but significant for noise sensitivity and visual annoyance. The above two moderators appear to indicate the features of respondents who are sensitive to stimuli or changes in their homeostasis.
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Exposición a Riesgos Ambientales , Ruido , Centrales Eléctricas , Trastornos del Sueño-Vigilia , Viento , Adulto , Fuentes Generadoras de Energía , Exposición a Riesgos Ambientales/efectos adversos , Exposición a Riesgos Ambientales/análisis , Exposición a Riesgos Ambientales/prevención & control , Exposición a Riesgos Ambientales/estadística & datos numéricos , Femenino , Humanos , Japón/epidemiología , Masculino , Salud Mental/estadística & datos numéricos , Ruido/efectos adversos , Ruido/prevención & control , Prevalencia , Salud Pública/métodos , Vigilancia en Salud Pública , Autoinforme , Trastornos del Sueño-Vigilia/diagnóstico , Trastornos del Sueño-Vigilia/epidemiología , Trastornos del Sueño-Vigilia/etiologíaRESUMEN
Studies of the pressure-dissociation of several amyloid or amyloid-like fibrils have shown that the fibril state is considerably voluminous. Quantitative characterization of the protein fibrillation reaction with respect to volumetric parameters is necessary to elucidate mechanisms of amyloid fibrillation in molecular terms such as protein cavity and hydration. Here we discuss, firstly, basic equations in statics and kinetics of protein polymerization as employed to obtain thermodynamic, volumetric, and kinetic parameters. Equilibrium treatment of the reactions with the scheme such as one-step polymerization, linear-association polymerization, or nucleation-dependent polymerization, and kinetic treatment of seeded linear-polymerization or spontaneous nucleation-elongation polymerization are described. In particular we will detail kinetics of the dissociation of fibrils which have been produced under the linear-association mechanism and therefore the length-distribution of which conforms to a geometric sequence in the degree of polymerization with a common ratio r, which is less than, and usually very close to, unity. In this case, an observed macroscopic rate of dissociation is shown to be a product of the microscopic elementary dissociation rate constant and a factor (1-r), extremely reduced compared with the intrinsic elementary rate. Secondly, we discuss protein conformational states in fibrillogenesis with molecular and volumetric observations reported, such as the unfolded state responsible for the association with seeds and the extension of amyloid fibrils, the transition state in which protein cavity formation and dehydration occur to intermediate levels, and the fibril state in which they occur to final respective levels which, in some cases, depend on the maturity of the fibril.
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Amiloide/química , Presión Hidrostática , Proteínas/química , Cinética , PolimerizacionRESUMEN
A disulfide-deficient variant of hen lysozyme, 0SS, is known to form an amyloid protofibril spontaneously, and to dissociate into monomers at high hydrostatic pressure. We carried out native PAGE at various temperatures (20-35°C) and pressures (0.1-200 MPa), to characterize the dissociation equilibrium of disulfide-deficient variant of hen lysozyme amyloid protofibril. Based on the density profiles, the partial molar volume and thermal expansibility changes for dissociation, ΔvD and ΔeD , were obtained to be -74 cm(3) /mol at 25°C and -2.3 cm(3) mol(-1) K(-1) , respectively. The dissociation of amyloid fibril destroys the cross ß-structure, and such conformational destruction in native protein fold rarely accompanies negative thermal expansibility change. We discussed the negative thermal expansibility change in terms of hydration and structural packing of the amyloid protofibril.
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Amiloide/química , Amiloide/metabolismo , Muramidasa/química , Muramidasa/metabolismo , Animales , Pollos , Electroforesis en Gel de Poliacrilamida , Calor , Desplegamiento Proteico , TermodinámicaRESUMEN
The crucial step for the fatal neurodegenerative prion diseases involves the conversion of a normal cellular protein, PrP(C), into a fibrous pathogenic form, PrP(Sc), which has an unusual stability against heat and resistance against proteinase K digestion. A successful challenge to reverse the reaction from PrP(Sc) into PrP(C) is considered valuable, as it would give a key to dissolving the complex molecular events into thermodynamic and kinetic analyses and may also provide a means to prevent the formation of PrP(Sc) from PrP(C) eventually in vivo. Here we show that, by applying pressures at kbar range, the "proteinase K-resistant" fibrils (rHaPrP(res)) prepared from hamster prion protein (rHaPrP [23-231]) by seeding with brain homogenate of scrapie-infected hamster, becomes easily digestible. The result is consistent with the notion that rHaPrP(res) fibrils are dissociated into rHaPrP monomers under pressure and that the formation of PrP(Sc) from PrP(C) is thermodynamically controlled. Moreover, the efficient degradation of prion fibrils under pressure provides a novel means of eliminating infectious PrP(Sc) from various systems of pathogenic concern.
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Cricetinae , Proteínas PrPC/metabolismo , Proteínas PrPSc/metabolismo , Scrapie/patología , Animales , Encéfalo/metabolismo , Encéfalo/patología , Cricetinae/fisiología , Endopeptidasa K/metabolismo , Proteínas PrPC/análisis , Proteínas PrPSc/análisis , Presión , Conformación Proteica , Proteolisis , Scrapie/metabolismoRESUMEN
During oxidative folding, the formation of disulfide bonds has profound effects on guiding the protein folding pathway. Until now, comparatively little is known about the changes in the conformational dynamics in folding intermediates of proteins that contain only a subset of their native disulfide bonds. In this comprehensive study, we probe the conformational landscape of non-native states of lysozyme containing a single native disulfide bond utilizing nuclear magnetic resonance (NMR) spectroscopy, small-angle X-ray scattering (SAXS), circular dichroism (CD) data, and modeling approaches. The impact on conformational dynamics varies widely depending on the loop size of the single disulfide variants and deviates significantly from random coil predictions for both NMR and SAXS data. From these experiments, we conclude that the introduction of single disulfides spanning a large portion of the polypeptide chain shifts the structure and dynamics of hydrophobic core residues of the protein so that these regions exhibit levels of order comparable to the native state on the nanosecond time scale.
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Disulfuros/química , Pliegue de Proteína , Simulación de Dinámica Molecular , Muramidasa/química , Conformación ProteicaRESUMEN
Four species of 1SS-varinats of lysozyme were almost unstructured in water, judged from their near-UV CD and (1) H-(15) N-HSQC spectra. Some preferential structure might exist in such a disordered state, but the population of molecules in such a conformation must have been too small to be detected by spectroscopic methods. Indeed, our previous study showed that the addition of 30% glycerol induced the unstructured 2SS-variant of lysozyme to form a native-like structure. To extend this method to more disordered proteins, we attempted to detect some preferential structure latent in unstructured 1SS-variants by the glycerol-enhanced detection. Only in one molecular species of the four 1SS-variants, 1SS[6-127] containing a single disulfide bridge of Cys6-Cys127, a preferential structure was found in the presence of 50% glycerol. It was detected by near-UV CD measurements and the H/D exchange method combined with the NMR spectroscopy. The glycerol-induced structure in 1SS[6-127] was not localized only in the vicinity of Cys6-Cys127, and largely protected regions distributed themselves among A-, B-, and C-helices and Ile55 and Leu56. It was similar to the glycerol-induced structure in 2SS[6-127, 64-80] containing two disulfide bridges of Cys6-Cys127 and Cys64-Cys80, although the former was less rigid than the latter. The role of A-helix (residues 4-15) is proposed as an origin of excellent potential of Cys6-Cys127 for inducing a tertiary structure in the α-domain.
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Glicerol/química , Muramidasa/química , Dicroismo Circular , Espectroscopía de Resonancia Magnética , Conformación Proteica , Espectrofotometría UltravioletaRESUMEN
The dynamics of amyloid fibrils, including their formation and dissociation, could be of vital importance in life. We studied the kinetics of dissociation of the amyloid fibrils from wild-type hen lysozyme at 25°C in vitro as a function of pressure using Trp fluorescence as a probe. Upon 100-fold dilution of 8 mg ml(-1) fibril solution in 80 mM NaCl, pH 2.2, no immediate change occurred in Trp fluorescence, but at pressures of 50-450 MPa the fluorescence intensity decreased rapidly with time (k(obs) = 0.00193 min(-1) at 0.1 MPa, 0.0348 min(-1) at 400 MPa). This phenomenon is attributable to the pressure-accelerated dissociation of amyloid fibrils into monomeric hen lysozyme. From the pressure dependence of the rates, which reaches a plateau at ~450 MPa, we determined the activation volume ΔV(0) = -32.9 ± 1.7 ml mol(monomer)(-1) and the activation compressibility Δκ() = -0.0075 ± 0.0006 ml mol(monomer)(-1) bar(-1) for the dissociation reaction. The negative ΔV(0) and Δκ() values are consistent with the notion that the amyloid fibril from wild-type hen lysozyme is in a high-volume and high-compressibility state, and the transition state for dissociation is coupled with a partial hydration of the fibril.
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Amiloide/química , Modelos Químicos , Muramidasa/química , Animales , Sitios de Unión , Simulación por Computador , Activación Enzimática , Presión , Unión ProteicaRESUMEN
To elucidate the effects of specific disulfide bridges (Cys6-Cys127, Cys30-Cys115, Cys64-Cys80, and Cys76-Cys94) on the secondary structure of hen lysozyme, the vacuum-ultraviolet circular dichroism (VUVCD) spectra of 13 species of disulfide-deficient variants in which Cys residues were replaced with Ala or Ser residues were measured down to 170 nm at pH 2.9 and 25 degrees C using a synchrotron-radiation VUVCD spectrophotometer. Each variant exhibited a VUVCD spectrum characteristic of a considerable amount of residual secondary structures depending on the positions and numbers of deleted disulfide bridges. The contents of alpha-helices, beta-strands, turns, and unordered structures were estimated with the SELCON3 program using the VUVCD spectra and PDB data of 31 reference proteins. The numbers of alpha-helix and beta-strand segments were also estimated from the VUVCD data. In general, the secondary structures were more effectively stabilized through entropic forces as the number of disulfide bridges increased and as they were formed over larger distances in the primary structure. The structures of three-disulfide variants were similar to that of the wild type, but other variants exhibited diminished alpha-helices with a border between the ordered and disordered structures around the two-disulfide variants. The sequences of the secondary structures were predicted for all the variants by combining VUVCD data with a neural-network method. These results revealed the characteristic role of each disulfide bridge in the formation of secondary structures.
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Dicroismo Circular/métodos , Disulfuros/química , Muramidasa/química , Sincrotrones , Animales , Humanos , Estructura Secundaria de ProteínaRESUMEN
2SS[6-127,64-80] variant of lysozyme which has two disulfide bridges, Cys6-Cys127 and Cys64-Cys80, and lacks the other two disulfide bridges, Cys30-Cys115 and Cys76-Cys94, was quite unstructured in water, but a part of the polypeptide chain was gradually frozen into a native-like conformation with increasing glycerol concentration. It was monitored from the protection factors of amide hydrogens against H/D exchange. In solution containing various concentrations of glycerol, H/D exchange reactions were carried out at pH* 3.0 and 4 degrees C. Then, (1)H-(15)N-HSQC spectra of partially deuterated protein were measured in a quenching buffer for H/D exchange (95% DMSO/5% D(2)O mixture at pH* 5.5 adjusted with dichloroacetate). In a solution of 10% glycerol, the protection factors were nearly equal to 10 at most of residues. With increasing glycerol concentration, some selected regions were further protected, and their protection factors reached about a 1000 in 30% glycerol solution. The highly protected residues were included in A-, B-, and C-helices and beta3-strand, and especially centered on Ile 55 and Leu 56. In 2SS[6-127,64-80], long-range interactions were recovered due to the preferential hydration by glycerol in the hydrophobic box of the alpha-domain. Glycerol-induced recovering of the native-like structure is discussed from the viewpoint of molten globules growing with the protein folding. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 665-675, 2009.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.
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Muramidasa/química , Animales , Pollos , Óxido de Deuterio , Disulfuros/química , Variación Genética , Glicerol/farmacología , Técnicas In Vitro , Modelos Moleculares , Muramidasa/genética , Resonancia Magnética Nuclear Biomolecular , Conformación Proteica/efectos de los fármacos , Pliegue de Proteína/efectos de los fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/genéticaRESUMEN
We report here results of the first direct measurement of partial volume and compressibility changes of a protein as it forms an amyloid protofibril. We use a high precision density meter and an ultrasonic velocity meter on a solution of intrinsically denatured, disulfide-deficient variant of hen lysozyme, and follow the time-dependent changes in volume and compressibility, as the protein spontaneously forms a protofibril. We have found a large increase in partial specific volume with time from 0.684 to 0.724 mL x g-1 (Deltanu = 0.040 mL x g-1 corresponding to 570 mL x (mol monomer)-1) and in partial specific adiabatic compressibility coefficient from -7.48 x 10(-12) to +1.35 x 10(-12) cm2 x dyn-1 (Deltabetas = 8.83 x 10(-12) x cm2 x dyn-1) as the monomer transforms into a protofibril. The results demonstrate that the protofibril is a highly voluminous and compressible entity, disclosing a cavity-rich, fluctuating nature for the amyloid protofibril. The volume and compressibility changes occur in two phases, the faster one preceding the major development of the beta-structure in the protofibril as monitored by CD.
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Amiloide/química , Animales , Fenómenos Biomecánicos , Dicroismo Circular , Cinética , Muramidasa/química , Factores de Tiempo , UltrasonidoRESUMEN
We present here the first detailed kinetic analysis of the dissociation reaction of amyloid protofibrils by utilizing pressure as an accelerator of the reaction. The experiment is carried out on an excessively diluted typical protofibril solution formed from an intrinsically denatured disulfide-deficient variant of hen lysozyme with Trp fluorescence as the reporter in the pressure range 3-400 MPa. From the analysis of the time-dependent fluorescence decay and the length distribution of the protofibrils measured on atomic force microscopy, we conclude that the protofibril grows or decays by attachment or detachment of a monomer at one end of the protofibril with a monomer dissociation rate independent of the length of the fibril. Furthermore, we find that the dissociation reaction is strongly dependent on pressure, characterized with a negative activation volume DeltaV(odouble dagger) = -50.5 +/- 1.60 ml mol(-1) at 0.1 MPa and with a negative activation compressibility Deltakappa(double dagger) = -0.013 +/- 0.001 ml mol(-1) bar(-1) or -0.9 x 10(-6) ml g(-1) bar(-1). These results indicate that the protofibril is a highly compressible high-volume state, but that it becomes less compressible and less voluminous in the transition state, most probably due to partial hydration of the existing voids. The system eventually reaches the lowest-volume state with full hydration of the monomer in the dissociated state.
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Péptidos beta-Amiloides/química , Biofisica/métodos , Animales , Pollos , Disulfuros/química , Cinética , Microscopía de Fuerza Atómica , Microscopía Fluorescente , Muramidasa/química , Fragmentos de Péptidos , Presión , Desnaturalización Proteica , Termodinámica , Factores de TiempoRESUMEN
BACKGROUND: The aim of this phase II study was to evaluate the efficacy of combination chemotherapy consisting of docetaxel and carboplatin in patients with inoperable non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: For this multicenter phase II study, the eligibility criteria included histologically or cytologically proven inoperable NSCLC, measurable lesions, Eastern Cooperative Oncology Group performance status (PS) 0-2, adequate organ and bone marrow functions, and written informed consent. Patients received 60 mg/m2 of docetaxel and carboplatin (target AUC 5.5) on day 1 every 3 weeks until disease progression. The primary end-point of this study was response rate and the secondary end-points were toxicities, time to progression and overall survival. RESULTS: A total of 40 patients were enrolled and 39 patients were eligible. A complete response and partial response were observed in 1 and 13 patients, respectively. An objective response rate was 35.9% (95% confidential interval [CI] 20.8-51.0%). The median time to progression was 5.2 months and the median overall survival was 12.0 months. The 1- and 2-year survival rates were 53.8% and 25.1%, respectively. The major toxicities were leukocytopenia and neutropenia. Grade 3 or 4 thrombocytopenia was rare and non-hematological toxicities were generally mild. Grade 3 non-hematological toxicities were observed in 6 patients (2 with nausea and vomiting, 1 with diarrhea, 1 with elevated transaminase levels, 1 with allergic reaction and 1 with edema). No grade 4 non-hematological toxicities were observed. CONCLUSION: Docetaxel and carboplatin combination chemotherapy was well tolerated and active in Japanese patients with advanced or metastatic NSCLC.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carboplatino/uso terapéutico , Carcinoma de Células Pequeñas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Taxoides/uso terapéutico , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Carcinoma de Células Pequeñas/patología , Progresión de la Enfermedad , Docetaxel , Femenino , Humanos , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Metástasis de la NeoplasiaRESUMEN
We report here a case of acute hypersensitivity pneumonitis induced by an oil fan heater. A 57-year-old man was admitted to our hospital because of fever, nonproductive cough, and dyspnea. Paeccilomyces variotii and Paeccilomyces nivea were identified from an oil fan heater in his house. The result of an environmental challenge test was positive. Intradermal reaction and precipitin results to sugar antigen of those fungi were positive only in the patient. This is the first described case of acute hypersensitivity pneumonitis caused by an oil fan heater.
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Alveolitis Alérgica Extrínseca/etiología , Aceites , Alveolitis Alérgica Extrínseca/diagnóstico por imagen , Alveolitis Alérgica Extrínseca/fisiopatología , Líquido del Lavado Bronquioalveolar , Exposición a Riesgos Ambientales , Humanos , Masculino , Persona de Mediana Edad , Paecilomyces/aislamiento & purificación , Tomografía Computarizada por Rayos XRESUMEN
This report describes NMR-spectroscopic investigations of the conformational dynamics of disulfide bonds in hen-egg-white lysozyme substitution mutants. The following four systems have been investigated: 2SS(alpha), a lysozyme variant that contains C64A, C76A, C80A and C94A substitutions, was studied in water at pH 2 and 3.8 and in urea (8 M, pH 2); 2SS(beta) lysozyme, which has C6S, C30A, C115A and C127A substitutions, was studied in water (pH 2) and urea (8 M, pH 2). The NMR analysis of heteronuclear 15N-relaxation rates shows that the barrier to disulfide-bond isomerisation can vary substantially in different lysozyme mutants and depends on the residual structure present in these states. The investigations reveal cooperativity in the modulation of micro- to millisecond dynamics that is due to the presence of multiple disulfide bridges in lysozyme. Mutation of cysteines in one of the two structural domains substantially diminishes the barrier to rotational isomerisation in the other domain. However, the interactions between hydrophobic clusters within and across the domains remains intact.
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Disulfuros/metabolismo , Muramidasa/química , Muramidasa/metabolismo , Mutación/genética , Animales , Pollos , Disulfuros/química , Concentración de Iones de Hidrógeno , Internet , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Muramidasa/genética , Desnaturalización Proteica/efectos de los fármacos , Estructura Terciaria de Proteína , Triptófano/química , Triptófano/metabolismo , Urea/farmacología , AguaRESUMEN
The dissociation and reassociation processes of amyloid protofibrils initiated by pressure-jump have been monitored with real-time (1)H NMR spectroscopy using an intrinsically denatured disulfide-deficient variant of hen lysozyme. Upon pressure-jump up to 2 kbar, the matured protofibrils grown over several months become fully dissociated into monomers within a few days. Upon pressure-jump down to 30 bar, the dissociated monomers immediately start reassociating. The association and dissociation cycle can be repeated reproducibly by alternating pressure, establishing a notion that the protofibril formation is simply a slow kinetic process toward thermodynamic equilibrium. The outstanding simplicity and effectiveness of pressure in controlling the protofibril formation opens a new route for investigating mechanisms of amyloid fibril-forming reactions. The noted variation in the pressure-induced dissociation rate with the progress of the association reaction suggests multiple mechanisms for the elongation of the protofibril. The disulfide-deficient hen lysozyme offers a particularly simple model system for thermodynamic and kinetic studies of protofibril formation as well as for screening drugs for amyloidosis.
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Amiloide/fisiología , Muramidasa/fisiología , Amiloide/ultraestructura , Animales , Pollos , Microscopía de Fuerza Atómica , Muramidasa/ultraestructura , Resonancia Magnética Nuclear Biomolecular , Presión , Desnaturalización Proteica , TermodinámicaRESUMEN
Although angiotensin II (Ang II) causes bronchoconstriction and bronchial hyperresponsiveness to methacholine in mildly asthmatic patients, the responsible mechanisms for these reactions are unclear. The authors examined the effect of intravenous infusion of Ang II on airway constriction in guinea pigs. Furthermore, the effects of subthreshold concentrations of Ang II on bronchial responsiveness to methacholine were investigated. Airway opening pressure (Pao), an index of bronchoconstriction, increased dose dependently after intravenous infusion of 3 and 10 nmol/kg Ang II (72.2 and 236.5 increase above the baseline value, respectively). In another set of experiments, animals received a methacholine inhalation challenge under a constant intravenous infusion of a subthreshold dose of Ang II (2 nmol/kg/min). The Ang II infusion elicited bronchial hyperresponsiveness to methacholine. The provocative concentration of methacholine, which produced a 200% increase above the baseline Pao (PC200), decreased from 306.9 to 156.1 micrograms/mL upon Ang II infusion. Pretreatment with TCV-116, a type 1 Ang II (AT1) receptor antagonist, but not PD123319, a type 2 Ang II (AT2) receptor antagonist, dose dependently prevented both the Ang II-induced bronchoconstriction and bronchial hyperresponsiveness to methacholine. The authors conclude that Ang II caused bronchoconstriction and induced bronchial hyperresponsiveness to methacholine via the AT1 receptors and that this effect did not involve the release of other bronchoactive mediators.
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Angiotensina II/farmacología , Hiperreactividad Bronquial/fisiopatología , Broncoconstricción/efectos de los fármacos , Receptor de Angiotensina Tipo 1/fisiología , Tetrazoles , Vasoconstrictores/farmacología , Bloqueadores del Receptor Tipo 1 de Angiotensina II , Animales , Antiasmáticos/farmacología , Antihipertensivos/farmacología , Azepinas/farmacología , Bencimidazoles/farmacología , Compuestos de Bifenilo/farmacología , Compuestos Bicíclicos con Puentes/farmacología , Hiperreactividad Bronquial/inducido químicamente , Broncoconstricción/fisiología , Broncoconstrictores/farmacología , Capsaicina/farmacología , Cromonas/farmacología , Ácidos Grasos Monoinsaturados/farmacología , Cobayas , Imidazoles/farmacología , Masculino , Cloruro de Metacolina/farmacología , Inhibidores de Agregación Plaquetaria/farmacología , Piridinas/farmacología , Taquifilaxis , Triazoles/farmacologíaRESUMEN
Our earlier NMR study showed that a two-disulfide variant of hen lysozyme containing intra-alpha-domain disulfide bridges, C6-C127 and C30-C115, is partially folded, with the alpha domain tightly folded to the nativelike conformation and the beta domain flexible or unfolded. With a view that the formation of a third disulfide bridge is a key for the accomplishment of the overall chain fold, three-dimensional structures of three-disulfide variants of hen lysozyme lacking one disulfide bridge (C64A/C80A, C76A/C94A, and C30A/C115A) were studied in detail using NMR spectroscopy. Amide hydrogen exchange rates were measured to estimate the degree of conformational fluctuation in a residue-specific manner. The structure of C76A/C94A was found to be quite similar to that of the wild type, except for the peptide segment of residues 74-78. The structure of C64A/C80A was considerably disordered in the entire region of the loop (residues 62-79). Further, it was found that a network of hydrogen bonds within the beta sheet and the 3(10) helix in the beta domain were disrupted and fluctuating. In C30A/C115A, the D helix was unstructured and the interface of the B helix with the D helix was significantly perturbed. However, the structural disorder generated in the hydrophobic core of the alpha domain was prevented by the C helix from propagating toward the beta domain. A marginally stable state in folded proteins is discussed based on the structures remaining in each three-disulfide variant.
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Disulfuros/química , Muramidasa/química , Amidas/química , Hidrógeno/química , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Conformación Proteica , Pliegue de ProteínaRESUMEN
Although a diversity of proteins is known to form amyloid fibers, their common mechanisms are not clear. Here, we show that an intrinsically unfolded protein (U), represented by a disulfide-deficient variant of hen lysozyme with no tertiary structure, forms an amyloid-like fibril after prolonged incubation. Using variable pressure NMR along with sedimentation velocity, circular dichroism, and fluorescence measurements, we show that, before the fibril formation, the protein forms a pressure-dissociable, soluble assemblage (U'(n)) with a sedimentation coefficient of 17 S and a rich intermolecular beta-sheet structure. The reversible assemblage is characterized with a Gibbs energy for association of -23.3 +/- 0.8 kJ.mol(-1) and a volume increase of 52.7 +/- 11.3 ml.mol(-1) per monomer unit, and involves preferential interaction of hydrophobic residues in the initial association step. These results indicate that amyloid fibril formation can proceed from an intrinsically denatured protein and suggest a scheme N <==>U <==>U'(n)-->fibril as a common mechanism of fibril formation in amyloidogenic proteins, where two-way arrows represent reversible processes, one-way arrow represents an irreversible process, and N, U, and U'(n)represent, respectively, the native conformer, the unfolded monomeric conformer, and the soluble assemblage of unfolded conformers.
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Amiloide/biosíntesis , Muramidasa/biosíntesis , Animales , Pollos/fisiología , Dicroismo Circular , Interacciones Hidrofóbicas e Hidrofílicas , Presión , Desnaturalización Proteica/fisiología , TermodinámicaRESUMEN
AIMS: There is no evidence demonstrating the clinical usefulness of phosphodiesterase (PDE) inhibitors in the treatment of asthma, although PDE3 and 4 inhibitors have received much attention for the treatment of bronchial asthma. We compared the bronchodilator effects of intravenously administered olprinone, a selective PDE3 inhibitor, and aminophylline, a nonselective PDE inhibitor, both alone and concomitantly. METHODS: In 12 patients with mild stable asthma, we compared the acute bronchodilator effects of the following two drugs, alone and together using a double-blind crossover design: intravenous administration of olprinone, 30 micro g min-1; aminophylline, 2.25 mg min-1; and olprinone plus aminophylline over a total period of 150 min. RESULTS: Mean maximal increase (95% confidence interval) in the FEV1 was 7.8% (2.4, 13.2), 17.1% (10.0, 24.2), 16.6% (11.2, 22.0), and 1.0% (-1.1, 3.1) during infusion of aminophylline, olprinone, aminophylline and olprinone, and saline, respectively. The magnitude of bronchodilatation produced by olprinone was greater than that by aminophylline. The combination of aminophylline and olprinone did not produce any greater bronchodilatation than olprinone alone. Olprinone alone or in combination with aminophylline lowered diastolic blood pressure, and increased heart rate. CONCLUSIONS: These results suggest that the intravenous administration of PDE3 inhibitors exhibits a bronchodilatory effect. There are no additive or synergistic effects of administration of olprinone and aminophylline at the same time.