9NSE:
reference: Mapping the active site polarity in structures of endothelial nitric oxide synthase heme domain complexed with isothioureas., Li H, Raman CS, Martasek P, Kral V, Masters BS, Poulos TL, J Inorg Biochem 2000 Aug 31;81(3):133-9. PMID: 11051558

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