In Anfinsen's classic experiments, purified ribonuclease A was completely denatured with 8 M urea and beta-mercaptoethanol, abolishing enzymatic activity. When the denaturants were removed and the protein was exposed to air, full catalytic activity was restored and the correct four disulfide bonds reformed spontaneously. The conclusion of this experiment was:

• A Disulfide bond formation in vivo requires a specific template RNA molecule
• B The primary amino acid sequence alone contains all the information needed to specify the native three-dimensional fold ✓
• C Ribonuclease activity depends on prosthetic groups that survive denaturation
• D Chaperone proteins are essential for the refolding of all denatured enzymes in vitro

Explanation

Anfinsen showed that ribonuclease refolds spontaneously to its native, active conformation once denaturants are removed, with disulfide pairs reforming correctly. This demonstrated thermodynamic self-folding: the native structure is the free-energy minimum dictated entirely by the primary sequence. Chaperones assist folding in the crowded cellular environment but are not required here, and no nucleic acid template or prosthetic group was involved.

Reference: Lehninger Principles of Biochemistry, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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