Hydrolyzes the cell wall of M.luteus more efficiently than that of B.licheniformis and B.subtilis. The C-terminal region, including the repeats, determines substrate specificity. Hydrolyzes the link between N-acetylmuramoyl residues and L-amino acid residues in certain cell-wall glycopeptides. Accumulates in cells as inclusion bodies. May be secreted by a mechanism different from the normal export system. Belongs to the N-acetylmuramoyl-L-alanine amidase 3 family.