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Probe diffusion in cross‐linked actin gels
Author(s) -
Newman Jay,
Schick Kenneth L.,
Zaner Ken S.
Publication year - 1989
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360281113
Subject(s) - chemistry , dispersity , diffusion , analytical chemistry (journal) , dynamic light scattering , polymerization , scattering , size exclusion chromatography , degree of polymerization , polystyrene , chromatography , polymer , polymer chemistry , thermodynamics , optics , materials science , nanotechnology , organic chemistry , physics , nanoparticle , enzyme
The diffusion of monodisperse polystyrene latex spheres (PLS) in column‐purified 0.65 mg/mL actin solutions, polymerized with 100 m M KCl in the absence and presence of a cross‐linker, actin binding protein (ABP), has been studied using dynamic light scattering. Measurements over a wide range of scattering angles from 90° to 8°, corresponding to inverse scattering vector probing distances of about 40–400 nm, respectively, give a measure of both the fraction of PLS mobile over the probing distance (from the normalized time autocorrelation function amplitude) and the average diffusion coefficient of the mobile PLS. Both 100‐ and 500‐nm diameter PLS are fully mobile in polymerized actin solutions over distances of less than 100 nm, as reported previously (Newman, J., Schick, K. S. & Gukelberger, G. Biophys. J. 53 , 573a, and Newman, J., Mroczka, N. & Schick, K. L. Biopolymers , 28 , 655–666). At increasing probing distances, or when ABP is added at molar ratios of 1 : 750 or 1 : 150, greater fractions of the PLS are immobilized, up to almost 99% at the conditions of a 400‐nm probing distance with 500‐nm probes and at a ratio of 1 : 150 added ABP to actin. The degree of immobilization correlates well with the amount of added ABP, the size of the PLS, and the probing distance. At increasing probe distances, as the degree of immobilization increases, the remaining mobile fraction of PLS has an increasing average diffusion coefficient. These results suggest a range of pore size in the actin gels with a mean size of a few hundred nanometers.