Sedimentation equilibrium

Sedimentation equilibrium is an analytical ultracentrifugation method for measuring protein molecular masses in solution and for studying protein-protein interactions. Particular applications of this technique are:
 * establishing the native state of a protein as a monomer, dimer, trimer, etc.
 * measuring the equilibrium constant for association of proteins which reversibly self-associate to form oligomers.
 * measuring the stoichiometry of complexes between two or more different proteins (e.g. a soluble receptor and its ligand or an antigen-antibody pair), or between a protein and a non-protein ligand.
 * measuring the equilibrium constants for reversible protein-protein and protein-ligand interactions (approximate range 1 nanomolar to 1 millimolar).