2Y60:
reference: The crystal structure of isopenicillin N synthase with delta-((L)-alpha-aminoadipoyl)-(L)-cysteinyl-(D)-methionine reveals thioether coordination to iron., Clifton IJ, Ge W, Adlington RM, Baldwin JE, Rutledge PJ, Arch Biochem Biophys. 2011 Dec 15;516(2):103-7. doi: 10.1016/j.abb.2011.09.014., Epub 2011 Oct 6. PMID: 22001738

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