John Kendrew and Max Perutz, at the Cavendish Laboratory in Cambridge, solve between 1958 and 1959, after more than twenty years of combined work, the first complete three-dimensional protein structures ever determined: myoglobin (Kendrew) and hemoglobin (Perutz). Both apply X-ray crystallography — a technique established decades earlier for small molecules — to molecules of far greater complexity, developing the "isomorphous replacement" method with heavy atoms to solve the mathematical problem of determining the three-dimensional position of thousands of atoms from diffraction patterns alone. The myoglobin structure reveals for the first time that a protein folds into a complex, specific three-dimensional shape — not a simple extended chain — with helical regions that Linus Pauling had theoretically predicted years earlier. The hemoglobin structure, considerably more complex since it is composed of four subunits, allows for the first time an understanding, at the molecular level, of how the protein transports oxygen in the blood and changes shape while doing so. Both works found protein crystallography as a scientific discipline, a technique that over subsequent decades would solve the structures of thousands of proteins, including the ribosome and numerous modern drug targets.