3A1R:
reference: A neutron crystallographic analysis of phosphate-free ribonuclease A at 1.7 A resolution., Yagi D, Yamada T, Kurihara K, Ohnishi Y, Yamashita M, Tamada T, Tanaka I, Kuroki R, Niimura N, Acta Crystallogr D Biol Crystallogr. 2009 Sep;65(Pt 9):892-9. Epub 2009, Aug 6. PMID: 19690366

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