3MWQ:
reference: Crystal structure of RNase A tandem enzymes and their interaction with the cytosolic ribonuclease inhibitor., Arnold U, Leich F, Neumann P, Lilie H, Ulbrich-Hofmann R, FEBS J. 2011 Jan;278(2):331-40. doi: 10.1111/j.1742-4658.2010.07957.x., Epub 2010 Dec 6. PMID: 21134128

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