Has anyone scanned all ~180,000 entries in the PDB for isopeptide bonds? https://proteopedia.org/w/Isopeptide_bond A forthcoming version of FirstGlance in Jmol (http://firstglance.jmol.org), still in preparation, will offer an alert when an isopeptide or NOS bond is detected, and offer to zoom in to show details. Knowing all the amino groups (besides lysine sidechains) that engage in isopeptide bonds is essential for this. For example, in 5JQF, the amino termini (Gly1) form isopeptide bonds with the sidechains of Asp9. -Eric Eric Martz, Professor Emeritus, Dept Microbiology (he/him/his) Univ. Massachusetts, Amherst -- Martz.MolviZ.Org <http://martz.molviz.org/> Guided Exploration of Macromolecules with Powerpoint-Ready Animations: FirstGlance.Jmol.Org <http://firstglance.jmol.org/> Protein 3D Structure Wiki: Proteopedia.Org <http://proteopedia.org/w/User:Eric_Martz> Education: Biochem in 3D at MolviZ.Org <http://molviz.org/> Find Functional Patches in Proteins: ConSurf.tau.ac.il <http://consurf.tau.ac.il/> Atlas of Macromolecules: Atlas.MolviZ.Org <http://atlas.molviz.org/> See multiple protein sequence alignments clearly: MSAReveal.Org <http://msareveal.org/> Pockets And Cavities Using Pseudoatoms in Proteins: PACUPP <http://molviz.org/pacupp> Interactive Molecules in Architectural Spaces: MolecularPlayground.Org <http://molecularplayground.org/> Syllabi: Workshops.MolviZ.Org <http://workshops.molviz.org/>