  Interactions between actin, an anionic polyelectrolyte, and lysozyme, a
cationic globular protein, have been examined using a combination of
synchrotron small-angle x-ray scattering and molecular dynamics simulations.
Lysozyme initially bridges pairs of actin filaments, which relax into
hexagonally-coordinated columnar complexes comprised of actin held together by
incommensurate one-dimensional close-packed arrays of lysozyme macroions. These
complexes are found to be stable even in the presence of significant
concentrations of monovalent salt, which is quantitatively explained from a
redistribution of salt between the condensed and the aqueous phases.
