Probably plays an important role in intracellular peptide degradation (PubMed:20067529). Release of an N-terminal amino acid, Xaa, from a peptide or arylamide. Xaa is preferably Glu or Asp but may be other amino acids, including Leu, Met, His, Cys and Gln. Binds 2 manganese ions per subunit. Homohexamer. A quadruple peptidase disruption (pepA, pepB, pepD and pepN) does not grow in M9 minimal medium, grows better when supplemented with casamino acids (PubMed:20067529). Belongs to the peptidase M17 family.