1QWQ:
reference: The swapping of terminal arms in ribonucleases: comparison of the solution structure of monomeric bovine seminal and pancreatic ribonucleases., Avitabile F, Alfano C, Spadaccini R, Crescenzi O, D'Ursi AM, D'Alessio G, Tancredi T, Picone D, Biochemistry 2003 Jul 29;42(29):8704-11. PMID: 12873130

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