1. Part a is adapted with permission from David Goodsell, doi:10
Part a is adapted with permission from David Goodsell, doi: / rcsb_pdb/mom_2002_2 (February 2002). Part b was
originally published in the J. Biol Chem. Maalcke, W. J. et al. Structural basis of biological NO generation by octaheme
oxidoreductases. 2014; 289: 1228–1242. © the American Society for Biochemistry and Molecular Biology. Part c is adapted
with permission from Rothery, R. A., Workun, G. J. & Weiner, J. H. The prokaryotic complex iron–sulfur molybdoenzyme family.
Biochim. Biophys. Acta 1778, 1897–1929 (2008), Elsevier. Part d is adapted with permission from Dietl, A. et al.
The inner workings of the hydrazine synthase multiprotein complex. Nature 527, 394–397 (2015), Macmillan Publishers Limited.