Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types
1944
The 1944 paper by Avery, MacLeod, and McCarty on the substance that changes one type of pneumococcus into another. They extracted a stringy liquid from killed Type III bacteria and showed it turned rough cells into smooth Type III cells, a change their descendants kept. Protein-digesting enzymes left it working, preparations that broke down DNA stopped it, and they concluded the substance is DNA.