Ionization and Structural Changes of the DMPG Vesicle along Its Anomalous Gel-Fluid Phase Transition: A Study with Different Lipid Concentrations

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dc.contributor.author Barroso, Rafael P.
dc.contributor.author Riske, Karin A. [UNIFESP]
dc.contributor.author Henriques, Vera B.
dc.contributor.author Teresa Lamy, M.
dc.date.accessioned 2016-01-24T14:05:28Z
dc.date.available 2016-01-24T14:05:28Z
dc.date.issued 2010-09-07
dc.identifier http://dx.doi.org/10.1021/la101784w
dc.identifier.citation Langmuir. Washington: Amer Chemical Soc, v. 26, n. 17, p. 13805-13814, 2010.
dc.identifier.issn 0743-7463
dc.identifier.uri http://repositorio.unifesp.br/handle/11600/32909
dc.description.abstract Dispersions of saturated anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG) have been extensively studied regarding their peculiar thermostructural behavior. At low ionic strength, the gel-fluid transition is spread along nearly 17 degrees C, displaying several thermal events in the calorimetric profile that is quite different from the single sharp peak around 23 degrees C found for higher ionic strength DMPG dispersions. To investigate the role of charge in the bilayer transition, we carefully examine the temperature dependence of the electrical conductivity of DMPG dispersions at different concentrations, correlating the data with the corresponding differential scanning calorimetry (DSC) traces. Electrical conductivity together with electrophoretic mobility measurements allowed the calculation of the dependence of the degree of ionization of DMPG vesicles on lipid concentration and temperature. It was shown that there is a decrease in vesicle charge as the lipid concentration increases, which is probably correlated with the increase in the concentration of bulk Na(+). Apart from the known increase in the electrical conductivity along the DMPG temperature transition region, a sharp rise was observed at the bilayer pretransition for all lipid concentrations studied, possibly indicating that the beginning of the chain melting process is associated with an increase in bilayer ionization. It is confirmed here that the gel-fluid transition of DMPG at low ionic strength is accompanied by a huge increase in the dispersion viscosity. However, it is shown that this measured macroviscosity is distinct from the local viscosity felt by either charged ions or DMPG charged aggregates in measurements of electrical conductivity or electrophoretic mobility, Data presented here give support to the idea that DMPG vesicles, at low ionic strength, get more ionized along the temperature transition region and could be perforated and/or deformed vesicle structures. en
dc.description.sponsorship USP
dc.description.sponsorship Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorship Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
dc.description.sponsorship Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.format.extent 13805-13814
dc.language.iso eng
dc.publisher Amer Chemical Soc
dc.relation.ispartof Langmuir
dc.rights Acesso restrito
dc.title Ionization and Structural Changes of the DMPG Vesicle along Its Anomalous Gel-Fluid Phase Transition: A Study with Different Lipid Concentrations en
dc.type Artigo
dc.contributor.institution Universidade de São Paulo (USP)
dc.contributor.institution Universidade Federal de São Paulo (UNIFESP)
dc.description.affiliation Univ São Paulo, Inst Fis, BR-01498 São Paulo, Brazil
dc.description.affiliation Universidade Federal de São Paulo, Dept Biofis, São Paulo, Brazil
dc.description.affiliationUnifesp Universidade Federal de São Paulo, Dept Biofis, São Paulo, Brazil
dc.identifier.doi 10.1021/la101784w
dc.description.source Web of Science
dc.identifier.wos WOS:000281354000016



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