Hæmoglobin F and the Genetic Control of Protein Structure

THE basic assumption of our concept 1 of a common metabolic pathway with different end-products depending on the nature or location of substitutions within the hæmoglobin molecule is not the direction in which the synthesis of the polypeptide chain may proceed, but the very premise itself—that the build-up occurs in a stepwise fashion. This is the all-important conclusion which we reached on purely deductive grounds on the basis of the observation that mutations apparently involving β-chain synthesis, for example, the thalassæmias observed by us, could selectively determine whether an excess of γ- or δ-chains is formed.