Extracellular aminopeptidase which contributes to pathogenicity. Binds 2 Zn(2+) ions per subunit. Activity is inhibited by EDTA, o-phenanthroline, bestatin and amastatin. Optimum pH is 7.0. Optimum temperatures are ranging from 40 to 50 degrees Celsius. Monomer. Expression is strongly increased during growth on protein-rich medium. Expressed at even higher levels when keratin is present in the protein-rich medium. Belongs to the peptidase M28 family. M28E subfamily.