Question

In the classic experiment of Christian Anfinsen, ribonuclease was unfolded in the presence of beta-mercaptoethanol and urea. When immediately assayed for retention of catalytic activity, it was virtually inactive. However, it was then refolded with substantial restoration of catalytic activity. A. If the removal of urea was carried out slowly, it should not matter if it was removed before or after beta-mercaptoethanol in order to recover most of the activity. B. If the beta-mercaptoethanol had been removed before the urea, only a fraction of the random disulfide pairs that are likely to form would have resulted in the restoration of catalytic activity. C. Because ribonuclease has disulfide bridges, it is essential to allow the bridges to reform before the urea is removed, or else no activity will be recovered. D. A critical feature of this experiment is that lysozyme has internal disulfide bridges that permit the recovery of activity after unfolding and refolding. However, recovery of activity would be much less likely to occur in a protein that has no internal disulfide bridges.

          In the classic experiment of Christian Anfinsen, ribonuclease was unfolded in the presence of beta-mercaptoethanol and urea. When immediately assayed for retention of catalytic activity, it was virtually inactive. However, it was then refolded with substantial restoration of catalytic activity.

A. If the removal of urea was carried out slowly, it should not matter if it was removed before or after beta-mercaptoethanol in order to recover most of the activity.

B. If the beta-mercaptoethanol had been removed before the urea, only a fraction of the random disulfide pairs that are likely to form would have resulted in the restoration of catalytic activity.

C. Because ribonuclease has disulfide bridges, it is essential to allow the bridges to reform before the urea is removed, or else no activity will be recovered.

D. A critical feature of this experiment is that lysozyme has internal disulfide bridges that permit the recovery of activity after unfolding and refolding. However, recovery of activity would be much less likely to occur in a protein that has no internal disulfide bridges.

Added by Sabrina V.

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