4LYS:
reference: 4-acyl pyrroles: mimicking acetylated lysines in histone code reading., Lucas X, Wohlwend D, Hugle M, Schmidtkunz K, Gerhardt S, Schule R, Jung M, Einsle O, Gunther S, Angew Chem Int Ed Engl. 2013 Dec 23;52(52):14055-9. doi: 10.1002/anie.201307652. , Epub 2013 Nov 24. PMID: 24272870

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