Suitability of double-stranded DNA as a molecular standard for the validation of analytical ultracentrifugation instruments

Methods for the Design and Analysis of Analytical Ultracentrifugation Experiments

“…Instead, further purification and fractionation of the sample may be desirable. For most systems, additional precision can be obtained by performing a global fit over multi-speed experiments and/or use of replicate samples in order to best identify the partial contributions of low-concentration contaminants or aggregates (Demeler & Gorbet, 2016;Ranasinghe et al, 2023). Whereas high-speed experiments emphasize the signal for sedimentation coefficients and composition, a low-speed experiment will allow all samples to diffuse long enough before pelleting to provide additional signal on the diffusion coefficient.…”

“…This will reduce the signal observed for the diffusion coefficient, which provides frictional information critical for shape and molecular weight calculations (Gorbet et al, 2018;Williams et al, 2018). To obtain the best signal for both sedimentation and diffusion coefficients, UltraScan offers global fitting of multi-speed experiments, which combine the strong diffusion signal from the slow experiment with the strong sedimentation and partial concentration signal from the high-speed experiment into a single solution (Ranasinghe et al, 2023). From such globally fitted data, molecular weight, partial specific volumes, or frictional properties can be obtained (Demeler et al, 2014).…”