1IPA:
reference: An enzyme with a deep trefoil knot for the active-site architecture., Nureki O, Shirouzu M, Hashimoto K, Ishitani R, Terada T, Tamakoshi M, Oshima T, Chijimatsu M, Takio K, Vassylyev DG, Shibata T, Inoue Y, Kuramitsu S, Yokoyama S, Acta Crystallogr D Biol Crystallogr 2002 Jul;58(Pt 7):1129-37. PMID: 12077432

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