4N9M:
reference: The neutron structure of urate oxidase resolves a long-standing mechanistic conundrum and reveals unexpected changes in protonation., Oksanen E, Blakeley MP, El-Hajji M, Ryde U, Budayova-Spano M, PLoS One. 2014 Jan 23;9(1):e86651. doi: 10.1371/journal.pone.0086651. eCollection, 2014 Jan 23. PMID: 24466188

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).