1KF2:
reference: Atomic resolution structures of ribonuclease A at six pH values., Berisio R, Sica F, Lamzin VS, Wilson KS, Zagari A, Mazzarella L, Acta Crystallogr D Biol Crystallogr 2002 Mar;58(Pt 3):441-50. PMID: 11856829

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