Alexis Rohou asked on Twitter In @UCSFChimeraX <https://twitter.com/UCSFChimeraX> 1.1.1 and #Isolde <https://twitter.com/hashtag/Isolde?src=hashtag_click> by @CrollTristan <https://twitter.com/CrollTristan> is there an easy way to add aa residues to the end of a chain? https://twitter.com/AlexisRohou/status/1386171500604977152 <https://twitter.com/AlexisRohou/status/1386171500604977152> Elaine says: There isn't an "add amino acid" yet in ChimeraX, only Chimera.... unless ISOLDE can do it (I don't know). So maybe it's an ISOLDE question. ChimeraX itself has building peptides from scratch but not sticking them on to the end of an existing peptide. Build Structure, Start Structure: peptide <https://rbvi.ucsf.edu/chimerax/docs/user/tools/buildstructure.html#start <https://rbvi.ucsf.edu/chimerax/docs/user/tools/buildstructure.html#start>> or command "build start peptide" <https://rbvi.ucsf.edu/chimerax/docs/user/commands/build.html#start <https://rbvi.ucsf.edu/chimerax/docs/user/commands/build.html#start>> Elaine