“…It has been assumed that the hormone's structure does not change significantly when it dimerizes but it is difficult to prove this unequivocally. Indeed, spectroscopic studies have suggested that the insulin monomer partially unwinds in solution (Pocker & Biswas, 1980), which would invalidate the structure-function arguments (Blundell, Dodson, Hodgkin & Mercola, 1972;Peking Insulin Structure Research Group, 1974). However, the crystal structure of DPI shows that this modified monomer is closely similar to the insulin structure present in 2-Zn insulin and in the dimer forms of hagfish insulin and pig insulin (Cutfield, Cutfield, Dodson, Dodson, Reynolds & Vallely, 1981;Dodson, Dodson, Hodgkin & Reynolds, 1979).…”