Acid-sensitive auxiliary assisted atypical diubiquitin synthesis exploiting thiol-ene coupling

Atypical ubiquitin (Ub) chains are generally involved in intracellular physiological processes, while the molecular mechanisms underlying their regulation remain unclear. In this work, we report an acid-sensitive auxiliary group based bifunctional handle that can prepare Lys27-, Lys29- and Lys33-diUb analogs by thiol-ene coupling (TEC) in combination with native chemical ligation (NCL). A prominent advantage of this method is the rapid and effective removal of acid-sensitive auxiliary groups after the formation of the isopeptide bond mimic. Collectively, this work illustrates the utility of the new strategy in the simple and efficient production of homogeneous atypical diUb analogs for biochemical and biophysical studies.