Biology · Protein Folding

In classical Anfinsen's protein folding experiment, the enzymatically active ribonuclease is treated with β-mercaptoethanol and 8 M urea. Following this, several preparations were tested. Which one of the following steps will lead to the regaining of the full enzymatic activity of ribonuclease? A. Dialysis to remove both β-mercaptoethanol and 8 M urea, followed by the addition of trace amounts of β-mercaptoethanol to catalyze disulfide exchange. B. Dialysis to remove both β-mercaptoethanol and 8 M urea, followed by complete oxidation in 8 M urea. C. Dialysis to remove both β-mercaptoethanol and 8 M urea, followed by the addition of 8 M urea to the dialyzed sample. D. Dialysis to remove both β-mercaptoethanol and 8 M urea alone, without any further treatment.