THE EVOLUTION OF RIBONUCLEOTIDE REDUCTION

Ribonucleotide reduction was essential for the transition from RNA to DNA by supplying deoxyribonucleotide precursors. The reaction requires free radical chemistry. Three quite different classes of ribonucleoti de reductases are known today. All three are proteins containing a sta ble free radical amino acid, but each uses a different mechanism for i ts generation. Did they evolve from a common ancestor, with the arriva l of atmospheric oxygen providing the driving force for their divergen ce, or was each a separate evolutionary invention?.