2-Aminomethylthiirane was used to attach a 1,2-amino-thiol moiety at thiol groups of peptides for use in peptide ligation to produce isopeptide mimetics. To confirm the strategy, a ubiquitinated histone H3 peptide was prepared, and the ubiquitin was correctly folded judging from CD spectra with no influence by the random H3 peptide. (C) 2016 Elsevier Ltd. All rights reserved.