Dynamic light-scattering study on polymerization process of muscle actin

Junji Masai, Shin'ichi Ishiwata, Satoru Fujime

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    Globular actin (G-actin) polymerizes into a fibrous form (F-actin) under physiological salt conditions. The polymerization process of muscle actin was studied by a dynamic light-scattering method. The intensity correlation functions G2(τ) of scattered light from a G-actin solution containing 2 mM Tris-HC1 (pH 8.0) and 0.1 mM ATP were analyzed by a cumulant expansion method, and the translational diffusion coefficient was determined to be D = (8.07 ± 0.10) × 10-7 cm2/s at 20°C. This D value gave a diameter of 5.3 nm for spherical G-actin including a hydration layer. Polymerization of 1-3 mg/ml G-actin in a solution containing 10 mM Tris-HC1 (pH 8.0), 0.2 mM ATP and 60 mM KC1 was followed by successive measurements of G2(τ) for a data accumulation period of 60-300 s/run. The time evolution of G2(τ) was analyzed by a least-squares fitting to the field correlation function of a multiexponential form g1 (τ) = σiAi exp(- Γiτ) with Γ1 > Γ2 > Γ3 > ..., and the static scattering intensity I(t) = <I > as a function of time t after initiation of polymerization was decomposed as I(t =σiAi. At the early stage of polymerization, a two-exponential fit gave results indicating that component 1 came from G-actin and component 2 from F-actin growing linearly with t. At the middle stage of polymerization, a three-exponen tial fit gave the results that component 1 came from G-actin and possibly its small oligomers, component 2 from polymers with a number-average length Ln of about 900 nm which was independent of t, and component 3 from 'ghosts' in dynamic light scattering in a semidilute regime. Component 3 was concluded to arise from restricted motions of polymers with lengths much longer than Ln in cages formed by polymers giving component 2, and a fragmentation-elongation process of F-actin was suggested to start at the middle stage of polymerization, resulting in the size redistribution of F-actin.

    Original languageEnglish
    Pages (from-to)253-269
    Number of pages17
    JournalBiophysical Chemistry
    Volume25
    Issue number3
    DOIs
    Publication statusPublished - 1986 Dec 31

    Fingerprint

    Dynamic light scattering
    muscles
    Polymerization
    Muscle
    Actins
    light scattering
    polymerization
    Muscles
    adenosine triphosphate
    polymers
    Polymers
    ghosts
    Dynamic Light Scattering
    oligomers
    Adenosine Triphosphate
    elongation
    hydration
    fragmentation
    diffusion coefficient
    salts

    Keywords

    • Actin polymerization
    • Diffusion coefficient
    • Dynamic light scattering
    • Quasistationary process
    • Spontaneous fragmentation

    ASJC Scopus subject areas

    • Biochemistry
    • Biophysics
    • Physical and Theoretical Chemistry

    Cite this

    Dynamic light-scattering study on polymerization process of muscle actin. / Masai, Junji; Ishiwata, Shin'ichi; Fujime, Satoru.

    In: Biophysical Chemistry, Vol. 25, No. 3, 31.12.1986, p. 253-269.

    Research output: Contribution to journalArticle

    Masai, Junji ; Ishiwata, Shin'ichi ; Fujime, Satoru. / Dynamic light-scattering study on polymerization process of muscle actin. In: Biophysical Chemistry. 1986 ; Vol. 25, No. 3. pp. 253-269.
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    abstract = "Globular actin (G-actin) polymerizes into a fibrous form (F-actin) under physiological salt conditions. The polymerization process of muscle actin was studied by a dynamic light-scattering method. The intensity correlation functions G2(τ) of scattered light from a G-actin solution containing 2 mM Tris-HC1 (pH 8.0) and 0.1 mM ATP were analyzed by a cumulant expansion method, and the translational diffusion coefficient was determined to be D = (8.07 ± 0.10) × 10-7 cm2/s at 20°C. This D value gave a diameter of 5.3 nm for spherical G-actin including a hydration layer. Polymerization of 1-3 mg/ml G-actin in a solution containing 10 mM Tris-HC1 (pH 8.0), 0.2 mM ATP and 60 mM KC1 was followed by successive measurements of G2(τ) for a data accumulation period of 60-300 s/run. The time evolution of G2(τ) was analyzed by a least-squares fitting to the field correlation function of a multiexponential form g1 (τ) = σiAi exp(- Γiτ) with Γ1 > Γ2 > Γ3 > ..., and the static scattering intensity I(t) = <I > as a function of time t after initiation of polymerization was decomposed as I(t =σiAi. At the early stage of polymerization, a two-exponential fit gave results indicating that component 1 came from G-actin and component 2 from F-actin growing linearly with t. At the middle stage of polymerization, a three-exponen tial fit gave the results that component 1 came from G-actin and possibly its small oligomers, component 2 from polymers with a number-average length Ln of about 900 nm which was independent of t, and component 3 from 'ghosts' in dynamic light scattering in a semidilute regime. Component 3 was concluded to arise from restricted motions of polymers with lengths much longer than Ln in cages formed by polymers giving component 2, and a fragmentation-elongation process of F-actin was suggested to start at the middle stage of polymerization, resulting in the size redistribution of F-actin.",
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    AB - Globular actin (G-actin) polymerizes into a fibrous form (F-actin) under physiological salt conditions. The polymerization process of muscle actin was studied by a dynamic light-scattering method. The intensity correlation functions G2(τ) of scattered light from a G-actin solution containing 2 mM Tris-HC1 (pH 8.0) and 0.1 mM ATP were analyzed by a cumulant expansion method, and the translational diffusion coefficient was determined to be D = (8.07 ± 0.10) × 10-7 cm2/s at 20°C. This D value gave a diameter of 5.3 nm for spherical G-actin including a hydration layer. Polymerization of 1-3 mg/ml G-actin in a solution containing 10 mM Tris-HC1 (pH 8.0), 0.2 mM ATP and 60 mM KC1 was followed by successive measurements of G2(τ) for a data accumulation period of 60-300 s/run. The time evolution of G2(τ) was analyzed by a least-squares fitting to the field correlation function of a multiexponential form g1 (τ) = σiAi exp(- Γiτ) with Γ1 > Γ2 > Γ3 > ..., and the static scattering intensity I(t) = <I > as a function of time t after initiation of polymerization was decomposed as I(t =σiAi. At the early stage of polymerization, a two-exponential fit gave results indicating that component 1 came from G-actin and component 2 from F-actin growing linearly with t. At the middle stage of polymerization, a three-exponen tial fit gave the results that component 1 came from G-actin and possibly its small oligomers, component 2 from polymers with a number-average length Ln of about 900 nm which was independent of t, and component 3 from 'ghosts' in dynamic light scattering in a semidilute regime. Component 3 was concluded to arise from restricted motions of polymers with lengths much longer than Ln in cages formed by polymers giving component 2, and a fragmentation-elongation process of F-actin was suggested to start at the middle stage of polymerization, resulting in the size redistribution of F-actin.

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