1. Macromolecule structures and experimental approaches

One of the first 3D structures of biological macromolecules was that of deoxyribonucleic acid, DNA, proposed as a double helix by Watson and Crick in 1953. This structure, supported by fiber diffraction data from crystallographer Rosalind Franklin, showed an arrangement of purine and pyrimidine bases interacting by hydrogen bonds, the phosphodiester backbone on the surface, a large, wide, shallow groove and a small, narrow, deep groove formed by this arrangement, which can thus accommodate ligands. The first protein structures to be elucidated were those of myoglobin and hemoglobin, for which Kendrew and Perutz were awarded the Nobel Prize in 1962 (figure 1 ). They are considered the founding fathers of protein radiocrystallography....