SUMOstar protease is genetically engineered from yeast Ulp1. SUMOstar was designed to be resistant to cleavage by endogenous deubiquitinases to allow expression of SUMOstar fusion proteins in eukaryotic expression systems. SUMOstar protease specifically removes SUMOstar. Like SUMO protease 1, SUMOstar protease recognizes the tertiary structure of SUMOstar. SUMOstar protease functions over a wide temperature range (30°C optimal), pH (5.5-9.5) and ionic strength. SUMOstar protease contains a His6 tag at the N-terminus that can be easily removed by affinity chromatography.