Deubiquitinating enzyme (DUB) probes are provided that resemble native diubiquitin (diUB) with a similar linkage size and that may contain a Michael acceptor for trapping the DUB active-site cysteine. For example, both K63- and K48-linked diubiquitin probes are generated using a facile chemical ligation method, utilizing the linker compound 3-(2-(bromomethyl)-1,3-dioxolan-2-yl)prop-2-en-1-amine. The diUb probes are capable of labelling DUBs from different families and may be employed to reveal intrinsic linkage specificities of DUBs.