The polymerization of actin: Study by small angle neutron scattering

Robert Ivkov, Jeffrey G. Forbes, Sandra C. Greer

Research output: Contribution to journalArticle

Abstract

We report measurements of small angle neutron scattering from solutions of rabbit muscle G-actin at 3.00 mg/mL in D2O buffer solution, with [Ca2+]=0.52 mM and with [KCl]=15, 8.9, and 5.4 mM. We observe the onset of the polymerization of G-actin to F-actin as the temperature is increased. The polymerization takes place on a time scale of 30-45 min for each temperature jump of 2°C-3°C. As the temperature is increased further, the average size of the polymers increases, and the characteristic length scale (or correlation length), ξ, of the F-actin in the dilute solution grows: ξ is about 10 Å below Tp, and about 70 Å a few degrees above Tp. The transition is sharper for lower concentrations of KCl. For the sample with [KCl]=8.9 mM, we observe a peak in ξ at about 2°C above Tp, which indicates a crossover into the semidilute regime. The transition is essentially reversible, but shows evidence of incomplete depolymerization on cycling. We are unable to apply the available theoretical model for reversible polymerization to rabbit muscle actin because of a lack of information on the enthalpy and entropy of polymerization. However, our observations for rabbit muscle actin are quite analogous to observations on the equilibrium polymerization of α-methylstyrene [A. P. Andrews, K. P. Andrews, S. C. Greer, F. Boué, and P. Pfeuty, Macromolecules 27, 3902 (1994)].

Original languageEnglish (US)
Pages (from-to)5599-5607
Number of pages9
JournalThe Journal of Chemical Physics
Volume108
Issue number13
StatePublished - Apr 1 1998
Externally publishedYes

Fingerprint

Neutron scattering
Actins
neutron scattering
polymerization
Polymerization
rabbits
muscles
Muscle
depolymerization
Depolymerization
macromolecules
temperature
low concentrations
Macromolecules
crossovers
Temperature
buffers
enthalpy
Enthalpy
entropy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

The polymerization of actin : Study by small angle neutron scattering. / Ivkov, Robert; Forbes, Jeffrey G.; Greer, Sandra C.

In: The Journal of Chemical Physics, Vol. 108, No. 13, 01.04.1998, p. 5599-5607.

Research output: Contribution to journalArticle

Ivkov, Robert ; Forbes, Jeffrey G. ; Greer, Sandra C. / The polymerization of actin : Study by small angle neutron scattering. In: The Journal of Chemical Physics. 1998 ; Vol. 108, No. 13. pp. 5599-5607.
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