Dielectric and calorimetric studies of hydrated purple membrane
Artikel i vetenskaplig tidskrift, 2005

Purple membranes (PM) from halobacteria were hydrated to ∼0.4 and ∼0.2 g H 2 O/g of PM and studied by dielectric spectroscopy and differential scanning calorimetry between 120 and 300 K. The dielectric process, attributed to a local (β) relaxation of the confined supercooled water, shows an Arrhenius temperature behavior at low temperatures. In the case of the most hydrated PM a small deviation from the Arrhenius behavior occurs at 190-200 K together with a pronounced endothermic process and an increased activation energy. The observed crossover is accompanied by a reduction of the interlayer spacing due to the partial loss of the intermembrane water. All these effects at ∼200 K are consistent with a scenario where the local relaxation process merges with a nonobservable α-relaxation of the interlayer water, giving rise to a more liquid-like behavior of the interfacial water. For the less hydrated sample the effects are less pronounced and shift to a slightly higher temperature. © 2005 by the Biophysical Society.


Peter Berntsen

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Rikard Bergman

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Helen Jansson

Chalmers, Teknisk fysik, Kondenserade materiens fysik

M. Weik

Institut de Biologie Structurale Jean-Pierre Ebel

Jan Swenson

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Biophysical Journal

0006-3495 (ISSN) 1542-0086 (eISSN)

Vol. 89 5 3111-3128


Annan teknik



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