1RFN:
reference: Coagulation factor IXa: the relaxed conformation of Tyr99 blocks substrate binding., Hopfner KP, Lang A, Karcher A, Sichler K, Kopetzki E, Brandstetter H, Huber R, Bode W, Engh RA, Structure Fold Des 1999 Aug 15;7(8):989-96. PMID: 10467148

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