Staphostatin B inhibits the cysteine protease Staphopain B, produced by Staphylococcus aureus, by blocking the active site of the enzyme. The domain adopts an eight-stranded mixed beta-barrel structure, with a deviation from the up-down topology of canonical beta-barrels in the amino-terminal part of the molecule [1].

1: A comparison of staphostatin B with standard mechanism serine protease inhibitors. Filipek R, Potempa J, Bochtler M; J Biol Chem. 2005;280:14669-14674. PMID:15644332