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Coupling of the hydration water dynamics and the internal dynamics of actin detected by quasielastic neutron scattering
Ist Teil von
Biochemical and biophysical research communications, 2013-02, Vol.431 (3), p.542-546
Ort / Verlag
United States: Elsevier Inc
Erscheinungsjahr
2013
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
► Quasielastic neutron scattering spectra of F-actin and G-actin were measured. ► Analysis of the samples in D2O and H2O provided the spectra of hydration water. ► The first layer hydration water around F-actin is less mobile than around G-actin. ► This difference in hydration water is in concert with the internal dynamics of actin. ► Water outside the first layer behaves bulk-like but influenced by the first layer.
In order to characterize dynamics of water molecules around F-actin and G-actin, quasielastic neutron scattering experiments were performed on powder samples of F-actin and G-actin, hydrated either with D2O or H2O, at hydration ratios of 0.4 and 1.0. By combined analysis of the quasielastic neutron scattering spectra, the parameter values characterizing the dynamics of the water molecules in the first hydration layer and those of the water molecules outside of the first layer were obtained. The translational diffusion coefficients (DT) of the hydration water in the first layer were found to be 1.2×10−5cm2/s and 1.7×10−5cm2/s for F-actin and G-actin, respectively, while that for bulk water was 2.8×10−5cm2/s. The residence times were 6.6ps and 5.0ps for F-actin and G-actin, respectively, while that for bulk water was 0.62 ps. These differences between F-actin and G-actin, indicating that the hydration water around G-actin is more mobile than that around F-actin, are in concert with the results of the internal dynamics of F-actin and G-actin, showing that G-actin fluctuates more rapidly than F-actin. This implies that the dynamics of the hydration water is coupled to the internal dynamics of the actin molecules. The DT values of the water molecules outside of the first hydration layer were found to be similar to that of bulk water though the residence times are strongly affected by the first hydration layer. This supports the recent observation on intracellular water that shows bulk-like behavior.