Hyper-mobility of water around actin filaments revealed using pulse-field gradient spin-echo 1H NMR and fluorescence spectroscopy

Tetsuichi Wazawa, Takashi Sagawa, Tsubasa Ogawa, Nobuyuki Morimoto, Takao Kodama, Makoto Suzuki

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

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 9.1ns 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.

Original languageEnglish
Pages (from-to)985-990
Number of pages6
JournalBiochemical and biophysical research communications
Volume404
Issue number4
DOIs
Publication statusPublished - 2011 Jan 28

Keywords

  • Actin polymerization
  • Endothermic process
  • Fluorescence anisotropy
  • Hyper-mobile water
  • Local viscosity
  • Rotational correlation time
  • Self-diffusion
  • Structure-breaker

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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