A potent, irreversible and specific inhibitor of deSUMOylation proteases (SENPs) that cleave SUMO2 conjugates. It is N-terminally tagged with a biotin, which allows for sensitive identification of SENPs using HRP-conjugated streptavidin in immunoblotting assays, or purification of SENPs using streptavidin resin. The biotin tag is separated from SUMO2 by an aminohexanoic acid (Ahx) linker that could increase the reactivity of the biotin moiety. In addition, Cys48 in SUMO2 was mutated to Ser.?