Aminopeptidase N is involved in the degradation of intracellular peptides generated by protein breakdown during normal growth as well as in response to nutrient starvation. Release of an N-terminal amino acid, Xaa-|-Yaa- from a peptide, amide or arylamide. Xaa is preferably Ala, but may be most amino acids including Pro (slow action). When a terminal hydrophobic residue is followed by a prolyl residue, the two may be released as an intact Xaa-Pro dipeptide. Binds 1 zinc ion per subunit. A quadruple peptidase disruption (pepA, pepB, pepD and pepN) does not grow in M9 minimal medium, does grow better when supplemented with casamino acids (PubMed:20067529). Belongs to the peptidase M1 family.