Fig. 2.

Sedimentation velocity profiles (g(s*) vs. s* curves) of commercially supplied holoHoSF from Calbiochem (black —), MP Biomedicals (green – –), Sigma-Aldrich (red ˙ ˙ ˙ ) compared to laboratory prepared holo-HoSF purified from frozen horse spleen as described in Materials and Methods (blue - ˙ - ). Sample conditions: 1.0 mg/mL ferritin in 0.1M MOPS, 0.15 M NaCl, pH 7.5. s* is defined as $s*(t_i,r_j)=\frac{1}{{\omega }^2{t}_i}\text{ln}(r_j/r_m)$ and is the transform of the radial axis of the centrifuge tube to the sedimentation coefficient axis where ω is the angular velocity, r_j is the radius in the solution and r_m is the radius of the meniscus and t_i is time. g(s*) is the concentration distribution function and is the concentration gradient on the s* axis, i.e. g(s*) = (∂c / ∂s*)_t. A detailed explanation of these quantities and their calculation can be found in reference [90].