Catalyzes the removal of dipeptides from the N-terminus of oligopeptides. Prefers Ala and hydrophobic residues at the P1 position, and has no preference for P2 residues. Shows the highest dipeptidyl peptidase activity toward the synthetic substrate Lys-Ala-methylcoumaryl-7-amide (Lys-Ala-MCA). Is likely involved in amino acid metabolism and bacterial growth/survival of asaccharolytic P.endodontalis, that utilizes amino acids from extracellular proteinaceous nutrients as energy and carbon sources. kcat is 21213 sec(-1) with Lys-Ala-MCA as substrate. kcat is 5175 sec(-1) with Met-Leu-MCA as substrate. kcat is 3468 sec(-1) with Ser-Tyr-MCA as substrate. kcat is 10378 sec(-1) with Gly-Phe-MCA as substrate. Optimum pH is 6.7, using Lys-Ala-MCA as substrate. Homodimer. Belongs to the peptidase S9C family.