Carboxypeptidase. Preferential cleavage: (Ac)2-L-Lys-D-Ala-|-D-Ala. Also transpeptidation of peptidyl-alanyl moieties that are N-acyl substituents of D-alanine. Inhibited by penicillin G. Not essential for cell growth. Since D.discoideum amoebae do not have a peptidoglycan cell wall, the function is not known. Belongs to the peptidase S13 family.