Samples of scUROD at 0.25 and 0.08 mg/mL were placed in two chambers of the centrifuge cell of a Beckman XL-A and spun at 12,000 rpm at 20° C to equilibrium. All data were fit globally to a monomer, resulting in a predicted molecular mass of 85,972 Da, consistent with the expected mass of the scUROD of 85,497 Da. (A) Points represent 268 averaged data values from the 5 scans (A280). The solid line is the best globally fit model. (B) Residuals for the scan shown in panel A.