cosedimentation cosedimentation through density gradient Sedimentation through a density gradient measures the sedimentation rate of a mixture of proteins through either a glycerol or sucrose gradient. Two interacting proteins will sediment mostly as a complex at concentrations above the binding constant. By varying the concentration of one or both of the complex constituents and taking into account the dilution of the species during sedimentation, one can reasonably accurately estimate the binding constant. density sedimentation PSI-MI MI:0029