RESUMEN
The development of peptide fusion inhibitors based on short synthetic peptides represents a promising option in the fight against HIV-1 infection, especially in individuals infected with multiresistant HIV-1 strains. GBV-C has the beneficial effect of retarding the progression of AIDS in people who are co-infected with both the GBV-C and HIV viruses. In previous works, the E1(22-39) GBV-C sequence (E1P8lin) was found to be capable of inhibiting the interaction of HIV-1 FP with bilayers and its cyclic analogue (E1P8cyc) showed a higher anti-HIV-1 activity. In the present work, in an attempt to gain a better understanding of the interaction of E1P8 peptides with HIV-1 FP, we analyzed direct interactions between peptides at the molecular level. Our results support that E1P8cyc might be more potent at blocking HIV-1 entry than E1P8lin as a consequence of the structure induced in the complex formed with HIV-1 FP, which is able to modify the conformation adopted by this functional domain of the HIV-1 gp41 protein in target cell membranes.
Asunto(s)
Fármacos Anti-VIH/farmacología , Virus GB-C/química , Inhibidores de Fusión de VIH/farmacología , VIH-1/efectos de los fármacos , VIH-1/metabolismo , Fragmentos de Péptidos/farmacología , Fármacos Anti-VIH/química , Relación Dosis-Respuesta a Droga , Inhibidores de Fusión de VIH/química , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Fragmentos de Péptidos/química , Relación Estructura-ActividadRESUMEN
With the aim of better understanding the fusion process mediated by the envelope proteins of the hepatitis G virus (HGV/GBV-C), we have investigated the interaction with model membranes of two overlapping peptides [(267-284) and (279-298)] belonging to the E2 structural protein. The peptides were compared for their ability to perturb lipid bilayers by means of different techniques such as differential scanning calorimetry and fluorescence spectroscopy. Furthermore, the conformational behaviour of the peptides in different membrane environments was studied by Fourier-transform infrared spectroscopy and circular dichroism. The results showed that only the E2(279-298) peptide sequence was able to bind with high affinity to negatively charged membranes, to permeabilize efficiently negative lipid bilayers, to induce haemolysis, and to promote inter-vesicle fusion. This fusogenic activity could be related to the induced peptide conformation upon interaction with the target membrane.
Asunto(s)
Virus GB-C/química , Membrana Dobles de Lípidos/química , Membranas Artificiales , Modelos Químicos , Proteínas del Envoltorio Viral/química , Dicroismo Circular/métodos , Estructura Secundaria de Proteína , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Proteínas del Envoltorio Viral/metabolismoRESUMEN
The present study was undertaken to examine the physicochemical properties of three overlapping peptides belonging to the E2 envelope protein of Hepatitis G virus (GBV-C/HGV) and its interaction with phospholipid biomembrane models using biophysical techniques. We describe our findings concerning the surface activity and the interaction of the peptides with monolayers and liposomes composed of the zwitterionic phospholipids dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine (DMPC) and a mixture of DMPC with the anionic phospholipid dimyristoylphosphatidylglycerol. The results inform about the effect of the chain length on their interaction with biomembrane models. The longest chain peptide interacts in a higher extent with all the phospholipid studied as a result of a combination of hydrophobic and electrostatic forces.
Asunto(s)
Virus GB-C/química , Membranas Artificiales , Modelos Químicos , Fragmentos de Péptidos/química , Fosfolípidos/química , Proteínas del Envoltorio Viral/química , Liposomas/química , Fragmentos de Péptidos/síntesis química , Propiedades de SuperficieRESUMEN
The physicochemical properties of three peptides belonging to the beta-interferon (beta-IFN) molecule, -beta-IFN(13-20), beta-IFN(40-47) and beta-IFN(109-116)-, which have been described to be antigenic epitopes of the neutralising antibodies responsible of the failure of the Multiple Sclerosis therapy, and their palmitoylated derivatives were analysed. Peptides were synthesised by solid-phase methodologies and characterized by amino acid analysis, analytical high-performance liquid chromatography and electrospray mass spectrometry. The activity of free and derivatized peptides was determined. In order to know how the synthesised peptides were able to interact with membrane models, studies of kinetics of penetration at constant area and compression isotherms were carried out. Moreover, differential scanning calorimetry (DSC) was used to investigate the thermotropic phase properties of binary mixtures of dipalmitoylphosphatidylcholine (DPPC) or dipalmitoylphosphatidylglicerol (DPPG) with the peptides.
Asunto(s)
1,2-Dipalmitoilfosfatidilcolina/metabolismo , Interferón beta/metabolismo , Membrana Dobles de Lípidos/química , Liposomas/química , Fragmentos de Péptidos/metabolismo , Fosfatidilgliceroles/metabolismo , 1,2-Dipalmitoilfosfatidilcolina/química , Rastreo Diferencial de Calorimetría , Cromatografía Líquida de Alta Presión , Interacciones Farmacológicas , Humanos , Interferón beta/química , Cinética , Membrana Dobles de Lípidos/metabolismo , Membranas , Modelos Químicos , Fragmentos de Péptidos/síntesis química , Fragmentos de Péptidos/química , Fosfatidilgliceroles/química , Estructura Terciaria de Proteína , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
The membrane-interacting properties of two potential epitopes of the GB virus C/Hepatitis G virus, located respectively at the regions (99-118) of the E2 structural protein and (440-460) of the NS3 non-structural protein were studied. Changes in the intrinsic fluorescence of Trp and Tyr residues after the addition of DPPC-LUV revealed that the peptide-membrane interaction was optimal above the gel-liquid crystalline transition temperature of the lipid. Differential scanning calorimetry studies showed that the E2 peptide incorporated into lipid bilayers perturbs the packing of lipids and affects their thermotropic properties. Moreover, the 20-mer structural peptide induced a slow leakage of vesicular contents at 55 degrees C.
RESUMEN
O objetivo do trabalho, é a determinaçäo de parâmetros definitórios do modelo de comportamento reológico da secreçäo mucóide das expectoraçöes, analisando as variaçöes produzidas em doentes tratadas ou näo como fármacos mucolíticos. Finalmente, é estudada a estabilidade da secreçäo mucóide frente a uma açäo de fricçäo repetitiva, definido o parâmetro de caracterizaçäo (coeficiente de perda logarítmica de viscosidade por ciclo), verificando, desta forma, sua estabilidade
Asunto(s)
Humanos , Esputo/análisis , Viscosidad , Expectorantes/farmacología , Esputo/efectos de los fármacosRESUMEN
O líquido pleural procedente de pacientes portadores de determinadas patologias apresenta uma concentraçäo elevada de hemácias, com valortes superiores a 5.000-6.000 hemácias/ml, valores mínimos necessários para obter uma coloraçäo sanguinolenta da soluçäo extraída. Esta causa obrigará posteriores realizaçöes, neste caso de tipo viscosimétrico, sobre amostras adicionadas de anticoagulante. Por causa disto, é necessário a análise cuidadosa das modificaçöes que o anticoagulante (heparina) exerce sobre os valores obtidos dos parâmetros definitórios do modelo de comportamento reológico do líquido pleural. Procedeu-se, pois, a caracterizaçäo reológica das amostras com elevada concentraçäo hemática, passando, a partir dos valores experimentais obtidos, a realizaçäo do teste estimativo de Darmois, comparativo de populaçöes de médias normais conhecidas
