N-acetylmuramyl-L-alanine amidase involved in innate immunity by degrading bacterial peptidoglycans (PGN). Probably plays a scavenger role by digesting biologically active PGN into biologically inactive fragments. Has no direct bacteriolytic activity. Hydrolyzes the link between N-acetylmuramoyl residues and L-amino acid residues in certain cell-wall glycopeptides. Binds 1 zinc ion per subunit. Monomer. Widely expressed. Expressed from old embryos. Expressed in larvae and adults. Strongly up-regulated by PGN from B.subtilis. Regulated by the imd/Relish pathway. Does not contain a signal sequence. Belongs to the N-acetylmuramoyl-L-alanine amidase 2 family.