 The acceptance of DNA as genetic material and of its structure brought the search for the material basis of genes to an end. Subsequently, the focus shifted on the question of how genes realized their heterocatalytic capacities. At this point, the question was reframed in terms of protein synthesis (Judson 1979: Ch. 6; Morange 2020: Ch. 12). Proteins consist of one or several polypeptide chains, which are composed of amino acids. In the early 1950s, Frederick Sanger (1918–2013) had determined the amino acid sequence for polypeptides of insulin (Chadarevian 1996). On this basis, Crick re-defined the problem by observing that