Sedimentation velocity of intrinsically disordered proteins: what information can we actually obtain?

Intrinsically disordered proteins are a challenge to characterise structurally because of their innate flexibility. Hydrodynamic methods such as sedimentation velocity analytical ultracentrifugation have been proposed as methods for their characterisation. By examining in detail this assumption we show that although velocity measurements do yield information on gross conformation, the information is restricted to only the weight averaged sedimentation and diffusion coefficients of the conformational ensemble.