4MLS:
reference: Structural Analysis and Optimization of the Covalent Association between SpyCatcher and a Peptide Tag., Li L, Fierer JO, Rapoport TA, Howarth M, J Mol Biol. 2013 Oct 23. pii: S0022-2836(13)00666-9. doi:, 10.1016/j.jmb.2013.10.021. PMID: 24161952

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