Temperature- and hydration-dependent internal dynamics of stripped human erythrocyte vesicles studied by incoherent neutron scattering.
BACKGROUND
We focus on temperature- and hydration-dependence of internal molecular motions in stripped human red blood cell (RBC) vesicles, widely used as a model system for more complex biomembranes.


METHODS
We singled out picosecond local motions of the non-exchangeable hydrogen atoms of RBC vesicles by performing elastic and quasielastic incoherent neutron scattering measurements in dry and heavy water (D₂O)-hydrated RBC powders.


RESULTS
In dry stripped RBCs, hydrogen motions remained harmonic all along the measured temperature range (100-310K) and mean-square displacements (MSDs) exhibited no temperature transition up to 310K. In contrast, MSDs of hydrated stripped RBCs (h ≈ 0.38g D₂O/g dry powder) exhibited a pronounced transition near 260K, with the sharp rise of anharmonic diffusive motions of hydrogen atoms. This transition at ~260K was correlated with both the onset of nonvibrational (harmonic and nonharmonic) motions and the melting of crystallized hydration water.


CONCLUSIONS
In conclusion, we have shown that MSDs in human RBC vesicles are temperature-and hydration-dependent. These results provide insight into biomembrane internal dynamics at picosecond timescale and nanometer length scale. Such motions have been shown to act as the "lubricant" of larger conformational changes on a slower, millisecond timescale that are necessary for important biological processes.
Laboratoire Léon-Brillouin, UMR 12 CEA/CNRS, Gif-sur-Yvette Cedex, France. spohie.combet@cea.fr
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S
Combet
J-M
JM
Zanotti
M-C
MC
Bellissent-Funel
D000465:Algorithms; D051398:Aquaporin 1 / Q000378:metabolism; D015153:Blotting, Western; D017666:Deuterium Oxide / Q000378:metabolism / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005612:Freeze Drying; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008854:Microscopy, Electron; D009502:Neutrons; D012542:Scattering, Radiation; D013696:Temperature; D014867:Water / Q000378:metabolism* / Q000494:pharmacology
C496020:AQP1 protein, human; D014867:Water; D051398:Aquaporin 1; D017666:Deuterium Oxide