Glass transition and dynamics in BSA-water mixtures over wide ranges of composition studied by thermal and dielectric techniques

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dc.contributor.author Panagopoulou, A en
dc.contributor.author Kyritsis, A en
dc.contributor.author Sabater I Serra, R en
dc.contributor.author Gomez Ribelles, JL en
dc.contributor.author Shinyashiki, N en
dc.contributor.author Pissis, P en
dc.date.accessioned 2014-03-01T02:02:15Z
dc.date.available 2014-03-01T02:02:15Z
dc.date.issued 2011 en
dc.identifier.issn 15709639 en
dc.identifier.uri http://hdl.handle.net/123456789/29298
dc.subject Dielectric relaxation en
dc.subject Glass transition en
dc.subject Hydrated protein en
dc.subject Molecular mobility en
dc.subject Plasticization en
dc.subject Uncrystallized water en
dc.subject.other bovine serum albumin en
dc.subject.other water en
dc.subject.other article en
dc.subject.other crystallization en
dc.subject.other differential scanning calorimetry en
dc.subject.other electrochemical impedance spectroscopy en
dc.subject.other glass transition temperature en
dc.subject.other priority journal en
dc.subject.other thermally stimulated luminescence en
dc.subject.other water content en
dc.subject.other Bovinae en
dc.title Glass transition and dynamics in BSA-water mixtures over wide ranges of composition studied by thermal and dielectric techniques en
heal.type journalArticle en
heal.identifier.primary 10.1016/j.bbapap.2011.07.014 en
heal.identifier.secondary http://dx.doi.org/10.1016/j.bbapap.2011.07.014 en
heal.publicationDate 2011 en
heal.abstract Protein-water dynamics in mixtures of water and a globular protein, bovine serum albumin (BSA), was studied over wide ranges of composition, in the form of solutions or hydrated solid pellets, by differential scanning calorimetry (DSC), thermally stimulated depolarization current technique (TSDC) and dielectric relaxation spectroscopy (DRS). Additionally, water equilibrium sorption isotherm (ESI) measurements were performed at room temperature. The crystallization and melting events were studied by DSC and the amount of uncrystallized water was calculated by the enthalpy of melting during heating. The glass transition of the system was detected by DSC for water contents higher than the critical water content corresponding to the formation of the first sorption layer of water molecules directly bound to primary hydration sites, namely 0.073 (grams of water per grams of dry protein), estimated by ESI. A strong plasticization of the Tg was observed by DSC for hydration levels lower than those necessary for crystallization of water during cooling, i.e. lower than about 0.3 (grams of water per grams of hydrated protein) followed by a stabilization of Tg at about - 80 °C for higher water contents. The α relaxation associated with the glass transition was also observed in dielectric measurements. In TSDC a microphase separation could be detected resulting in double Tg for some hydration levels. A dielectric relaxation of small polar groups of the protein plasticized by water, overlapped by relaxations of uncrystallized water molecules, and a separate relaxation of water in the crystallized water phase (bulk ice crystals) were also recorded. © 2011 Elsevier B.V. All Rights Reserved. en
heal.journalName Biochimica et Biophysica Acta - Proteins and Proteomics en
dc.identifier.doi 10.1016/j.bbapap.2011.07.014 en
dc.identifier.volume 1814 en
dc.identifier.issue 12 en
dc.identifier.spage 1984 en
dc.identifier.epage 1996 en

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