Mutant 1
Hao - source [http://www.rcsb.org/pdb/explore.do?structureId=1fgj 1FGJ]
cycA - source [http://www.rcsb.org/pdb/explore.do?structureId=1ft5 1FT5]
Mutant 2
NirS dimer with N2 - source [http://www.rcsb.org/pdb/explore/explore.do?structureId=1nno 1NNO]