Extracellular aminopeptidase that allows assimilation of proteinaceous substrates. Binds 2 Zn(2+) ions per subunit. Activity is strongly inhibited by metalchelating agents, such as EDTA and dipicolinic acid. Optimum pH is 7.1-10. Optimum temperature is 70 degrees Celsius. Monomer. Belongs to the peptidase M28 family. M28E subfamily.