Figure 3.

Experimental implementation of toSE for BSA under the conditions of Fig. 1C. Absorbance scans at 280 nm were acquired at each step in the rotor-speed profile, gradually decaying from an initial 41,600 rpm to the target equilibrium speed of 15,000 rpm during the first 5 h (following Fig. 1C, inset). Scans are radially translated to compensate for differential rotor stretching. (A) Experimental scans (dots) and best fit (lines) using the color scheme in the sidebar to indicate passage of time. The c(s) model produced the sedimentation coefficient distribution shown in the inset (solid line) and led to residuals shown in the lower plot with an RMSD of 0.0055 optical density (OD). The dotted line in the inset reflects the c(s) distribution obtained when only data from the first 3 h were considered. (B) The approach to equilibrium is visualized by the average buoyant molar mass obtained for data in the accessible radial range at different time points (red). For comparison, the results from a conventional SE experiment under equivalent conditions with constant rotor speed are shown in blue. The results of a replicate experiment are shown as dotted lines. The inset shows the time course of the RMSD difference between individual scans and the last scan for the toSE experiment (red) and the conventional approach to SE at constant speed (blue). To see this figure in color, go online.