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Liquid-like water confined in stacks of biological membranes at 200 k and its relation to protein dynamics
- Source :
- Biophysical journal. 89(5)
- Publication Year :
- 2005
-
Abstract
- Confined water is of considerable current interest owing to its biophysical importance and relevance to cryopreservation. It can be studied in its amorphous or supercooled state in the “no-man’s land”, i.e., in the temperature range between 150 and 235K, in which bulk water is always crystalline. Amorphous deuterium oxide (D2O) was obtained in the intermembrane spaces of a stack of purple membranes from Halobacterium salinarum by flash cooling to 77K. Neutron diffraction showed that upon heating to 200K the intermembrane water space decreased sharply with an associated strengthening of ice diffraction, indicating that water beyond the first membrane hydration layer flowed out of the intermembrane space to form crystalline ice. It was concluded that the confined water undergoes a glass transition at or below 200K to adopt an ultraviscous liquid state from which it crystallizes to form ice as soon as it finds itself in an unconfined, bulk-water environment. Our results provide model-free evidence for translational diffusion of confined water in the no-man’s land. Potential effects of the confined-water glass transition on nanosecond membrane dynamics were investigated by incoherent elastic neutron scattering experiments. These revealed no differences between flash-cooled and slow-cooled samples (in the latter, the intermembrane space at temperatures
- Subjects :
- Halobacterium salinarum
Neutrons
Phase transition
Time Factors
Chemistry
Neutron diffraction
Analytical chemistry
Biophysics
Temperature
Proteins
Water
Neutron scattering
Phase Transition
Amorphous solid
Solvation shell
Deuterium
Purple Membrane
Chemical physics
Scattering, Radiation
Glass
Other
Deuterium Oxide
Glass transition
Supercooling
Subjects
Details
- ISSN :
- 00063495
- Volume :
- 89
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- Biophysical journal
- Accession number :
- edsair.doi.dedup.....164b321410b3c04fd04d95a8c983e961