Glass Transition and Dynamics in Lysozyme-Water Mixtures Over Wide Ranges of Composition

Panagopoulou, A; Kyritsis, A; Aravantinou, A-M; Nanopoulos, D; i Serra, RS; Gomez Ribelles, JL; Shinyashiki, N; Pissis, P

dc.contributor.author	Panagopoulou, A	en
dc.contributor.author	Kyritsis, A	en
dc.contributor.author	Aravantinou, A-M	en
dc.contributor.author	Nanopoulos, D	en
dc.contributor.author	i Serra, RS	en
dc.contributor.author	Gomez Ribelles, JL	en
dc.contributor.author	Shinyashiki, N	en
dc.contributor.author	Pissis, P	en
dc.date.accessioned	2014-03-01T01:35:46Z
dc.date.available	2014-03-01T01:35:46Z
dc.date.issued	2011	en
dc.identifier.issn	1557-1858	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21184
dc.subject	Dielectric relaxation	en
dc.subject	Glass transition	en
dc.subject	Hydrated proteins	en
dc.subject	Molecular mobility	en
dc.subject	Plasticization	en
dc.subject	Uncrystallized water	en
dc.subject.classification	Food Science & Technology	en
dc.subject.other	Broadband dielectric relaxation spectroscopy	en
dc.subject.other	Bulk ice	en
dc.subject.other	Critical water content	en
dc.subject.other	Cryoprotection	en
dc.subject.other	Dielectric measurements	en
dc.subject.other	Dielectric techniques	en
dc.subject.other	Equilibrium sorption isotherms	en
dc.subject.other	Glass transition temperature	en
dc.subject.other	Globular proteins	en
dc.subject.other	Hydrated proteins	en
dc.subject.other	Hydrated solids	en
dc.subject.other	Ice crystals	en
dc.subject.other	Local relaxation	en
dc.subject.other	Molecular mobility	en
dc.subject.other	Plasticization	en
dc.subject.other	Polar groups	en
dc.subject.other	Potential impacts	en
dc.subject.other	Protein dynamics	en
dc.subject.other	Protein molecules	en
dc.subject.other	Protein surface	en
dc.subject.other	Room temperature	en
dc.subject.other	Thermally stimulated depolarization currents	en
dc.subject.other	Uncrystallized water	en
dc.subject.other	Water mixture	en
dc.subject.other	Water molecule	en
dc.subject.other	Crystals	en
dc.subject.other	Dielectric relaxation	en
dc.subject.other	Differential scanning calorimetry	en
dc.subject.other	Enzymes	en
dc.subject.other	Glass	en
dc.subject.other	Glass transition	en
dc.subject.other	Hydration	en
dc.subject.other	Molecules	en
dc.subject.other	Sorption	en
dc.subject.other	Spectroscopy	en
dc.subject.other	Water content	en
dc.title	Glass Transition and Dynamics in Lysozyme-Water Mixtures Over Wide Ranges of Composition	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/s11483-010-9201-0	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s11483-010-9201-0	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	Differential scanning calorimetry (DSC) and two dielectric techniques, broadband dielectric relaxation spectroscopy and thermally stimulated depolarization currents (TSDC), were employed to study glass transition and water and protein dynamics in mixtures of water and a globular protein, lysozyme, in wide ranges of water content, both solutions, and hydrated solid samples. In addition, water equilibrium sorption isotherms (ESI) measurements were performed at room temperature. The main objective was to correlate results by different techniques to each other and to determine critical water contents for various processes. From ESI measurements the content of water directly bound to primary hydration sites was determined to 0.088 (grams of water per grams of dry protein), corresponding to 71 water molecules per protein molecule, and that where clustering becomes significant to about 0.25. Crystallization and melting events of water were first observed at water contents 0.270 and 0.218, respectively, and the amount of uncrystallized water was found to increase with increasing water content. Two populations of ice crystals were observed by DSC, primary and bulk ice crystals, which give rise to two separate relaxations in dielectric measurements. In addition, the relaxation of uncrystallized water was observed, superimposed on a local relaxation of polar groups on the protein surface. The glass transition temperature, determined by DSC and TSDC in rather good agreement to each other, was found to decrease significantly with increasing water content and to stabilize at about -90 °C for water contents higher than about 0.25. This is a novel result of this study with potential impact on cryoprotection and pharmaceutics. © 2011 Springer Science+Business Media, LLC.	en
heal.publisher	SPRINGER	en
heal.journalName	Food Biophysics	en
dc.identifier.doi	10.1007/s11483-010-9201-0	en
dc.identifier.isi	ISI:000292979900003	en
dc.identifier.volume	6	en
dc.identifier.issue	2	en
dc.identifier.spage	199	en
dc.identifier.epage	209	en