| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1931269 | Biochemical and Biophysical Research Communications | 2011 | 6 Pages |
This paper reports that water molecules around F-actin, a polymerized form of actin, are more mobile than those around G-actin or in bulk water. A measurement using pulse-field gradient spin-echo 1H NMR showed that the self-diffusion coefficient of water in aqueous F-actin solution increased with actin concentration by ∼5%, whereas that in G-actin solution was close to that of pure water. This indicates that an F-actin/water interaction is responsible for the high self-diffusion of water. The local viscosity around actin was also investigated by fluorescence measurements of Cy3, a fluorescent dye, conjugated to Cys 374 of actin. The steady-state fluorescence anisotropy of Cy3 attached to F-actin was 0.270, which was lower than that for G-actin, 0.334. Taking into account the fluorescence lifetimes of the Cy3 bound to actin, their rotational correlation times were estimated to be 3.8 and 9.1 ns for F- and G-actin, respectively. This indicates that Cy3 bound to F-actin rotates more freely than that bound to G-actin, and therefore the local water viscosity is lower around F-actin than around G-actin.
Research highlights► Translationally hyper-mobile water has been detected around actin filaments. ► Translationally hyper-mobile water is formed upon polymerization of actin. ► Low water viscosity was found around F-actin using fluorescence anisotropy. ► Formation of hyper-mobile water may explain endothermic actin polymerization.
