Title: A Bifunctional Molecule-Assisted Synthesis of Mimics in Ubiquitination System

Brief: The bifunctional molecule CAET can be modified onto a Cys-only POI (an E2 or Ub), exposing an orthogonal reactive site for native chemical ligation (NCL) that allowed ligation covalently with a Ub-derived thioester, thus forming mimics of Ub chains or Ub charged E2. The Cys residue of CAET can further be linked to a deubiquitinase or a substrate to obtain decoupling or coupling intermediate mimics through disulfide exchange reaction.