Sortases are a family of membrane–anchored transpeptidases expressed by Gram–positive bacteria. Sortase A catalyzes the cleavage of C-terminal recognition motif (LPXTG) of multiple structurally unrelated proteins followed by formation of an amide bond with the peptidoglycan layer of the bacteria. Sortase A protease can be used with SensoLyte®520 Sortase A Activity Assay Kits (AnaSpec Cat# 72228) to screen for anti-infective agents.
Sortase A from Staphylcoccus aureus was expressed in E. coli expression system with a N-terminal His tag. It is comprised of 26-206 amino acids and its MW is 21.7-kDa. The activity of Sortase A can be measured in a FRET-based enzymatic assay (AnaSpec Cat# 72228). 100 ng of enzyme is sufficient for the assay. Sortase A is stored in 40 mM Tris-HCl, pH 8.0, 110 mM NaCl, and 2.2 mM KCl, 8 mM imidazole, 0.04% Tween 20, and 20 % glycerol. The purity is >87% as estimated on SDS PAGE.