Z-RLRGG-AMC is a fluorogenic substrate for the deubiquitinating enzyme isopeptidase T (IPaseT) and other ubiquitin C-terminal hydrolases (UCHs) based on the C-termini of ubiquitin with a kcat/Km value of 95 M?1s?1. Together with our product I-1685 it is used in continuous assays for precise mechanistic studies or microtiter plate assays for high-throughput inhibitor screening.