2FD9:
reference: Role of a salt bridge in the model protein crambin explored by chemical protein synthesis: X-ray structure of a unique protein analogue, [V15A]crambin-alpha-carboxamide., Bang D, Tereshko V, Kossiakoff AA, Kent SB, Mol Biosyst. 2009 Jul;5(7):750-6. Epub 2009 May 28. PMID: 19562114

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