1AWZ:
reference: Three-dimensional solution structure of human angiogenin determined by 1H,15N-NMR spectroscopy--characterization of histidine protonation states and pKa values., Lequin O, Thuring H, Robin M, Lallemand JY, Eur J Biochem 1997 Dec 15;250(3):712-26. PMID: 9461294

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