Anfinsen's Dogma

Thanks to Christian Anfinsen, we now know that the instructions for the folding of small globular proteins all come from the primary sequence itself. Anfinsen demonstrated this idea in 1962 by using a protein called ribonuclease A, which contains four disulfide bridges that are vital to protein structure and function. First, Anfinsen unfolded RNase A with the denaturant urea and βME, a reducing agent that breaks disulfide bridges. When Anfinsen removed urea first and βME second, the protein refolded and regained 100% activity. However, when he switched the order and removed βME first and urea second, the protein only regained 1% of its original activity. This result is attributed to the fact that removing βME when the enzyme is still unfolded causes cysteine residues to randomly form bonds with each other. The idea that the amino acid sequence acts as the "blueprint" for protein folding was later referred to as Anfinsen's dogma.

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