4MLV:
reference: Structural evidence for the partially oxidized dipyrromethene and dipyrromethanone forms of the cofactor of porphobilinogen deaminase: structures of the Bacillus megaterium enzyme at near-atomic resolution., Azim N, Deery E, Warren MJ, Wolfenden BA, Erskine P, Cooper JB, Coker A, Wood SP, Akhtar M, Acta Crystallogr D Biol Crystallogr. 2014 Mar;70(Pt 3):744-51. doi:, 10.1107/S139900471303294X. Epub 2014 Feb 15. PMID: 24598743

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