Activity-based diubiquitin probes for elucidating the linkage specificity of deubiquitinating enzymes

We report a new class of deubiquitinating enzyme (DUB) probes that resemble the native diubiquitin with a same linkage size and contain a Michael addition acceptor for trapping the DUB active-site cysteine. Both K63- and K48-linked diubiquitin probes were generated using a facile chemical ligation method. The diUb probes were demonstrated to label DUBs from different families and revealed intrinsic linkage specificities of DUBs.