1IPS:
reference: Crystal structure of isopenicillin N synthase is the first from a new structural family of enzymes., Roach PL, Clifton IJ, Fulop V, Harlos K, Barton GJ, Hajdu J, Andersson I, Schofield CJ, Baldwin JE, Nature 1995 Jun 22;375(6533):700-4. PMID: 7791906

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