2CW1:
reference: Design of lambda Cro fold: solution structure of a monomeric variant of the de novo protein., Isogai Y, Ito Y, Ikeya T, Shiro Y, Ota M, J Mol Biol. 2005 Dec 9;354(4):801-14. Epub 2005 Oct 21. PMID: 16289118

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