Structure of leghaemoglobin from lupin root nodules at 5 Å resolution

THE similarity in tertiary structure of mammalian haemoglobins1–3 and myoglobins4,5 and of haemoglobins from invertebrates6,7 shown by X-ray analysis has been particularly important for our understanding of the biological evolution of these proteins. We have therefore studied the structure of leghaemoglobins—plant haemoglobins found in root nodules of leguminous plants—and compared the structures of seemingly unrelated, in terms of evolution, haemoglobins.