Molecular weights from approach-to-sedimentation equilibrium data using nonlinear regression analysis

Data obtained from early times during the transient period of sedimentation equilibrium experiments are analyzed using an approximate solution to the Lamm equation to estimate s/D. The Cr versus r data obtained at several times during approach-to-equilibrium are analyzed using a nonlinear least squares algorithm and Fujita's approximate solution. This procedure was tested using D-Ser13-somatostatin, ribonuclease, and ovalbumin. The results obtained demonstrate that for monodisperse samples s/D may be rapidly and reliably estimated using this method.