3C4B:
reference: Structural and biochemical insights into the dicing mechanism of mouse Dicer: a conserved lysine is critical for dsRNA cleavage., Du Z, Lee JK, Tjhen R, Stroud RM, James TL, Proc Natl Acad Sci U S A. 2008 Feb 19;105(7):2391-6. Epub 2008 Feb 11. PMID: 18268334

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