Probably involved in the processing and regular turnover of intracellular proteins (PubMed:20067529). Catalyzes the removal of unsubstituted N-terminal amino acids from various peptides. Required for plasmid ColE1 site-specific recombination but not in its aminopeptidase activity. Could act as a structural component of the putative nucleoprotein complex in which the Xer recombination reaction takes place (PubMed:8057849). Release of an N-terminal amino acid, Xaa-|-Yaa-, in which Xaa is preferably Leu, but may be other amino acids including Pro although not Arg or Lys, and Yaa may be Pro. Amino acid amides and methyl esters are also readily hydrolyzed, but rates on arylamides are exceedingly low. Release of an N-terminal amino acid, preferentially leucine, but not glutamic or aspartic acids. Binds 2 manganese ions per subunit. Inhibited by zinc and EDTA. 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. The ligation for manganese is based on the ligation for zinc, an inhibitor, in the crystallographic structure reported in PubMed:10449417. The ligation for manganese in the active form of the enzyme may differ.