4FQD:
reference: Structural and functional characterization of NikO, an enolpyruvyl transferase essential in nikkomycin biosynthesis., Oberdorfer G, Binter A, Ginj C, Macheroux P, Gruber K, J Biol Chem. 2012 Sep 7;287(37):31427-36. doi: 10.1074/jbc.M112.352096. Epub 2012, Jul 18. PMID: 22810238

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