Insight into protein–protein interactions from analytical ultracentrifugation

Analytical ultracentrifugation is a free solution technique with no supplementary immobilization, columns or membranes required, and can be used to study self-association and hetero-interactions, stoichiometry, reversibility and interaction strength across a very large dynamic range (dissociation constants from 10⁻¹² M to 10⁻¹ M). In the present paper, we review some of the advances that have been made in the two different types of sedimentation experiment – sedimentation equilibrium and sedimentation velocity – for the analysis of protein–protein interactions and indicate how major complications such as thermodynamic and hydrodynamic non-ideality can be dealt with.