Cell wall formation. May play a specialized role in remodeling the cell wall. Specifically hydrolyzes the DD-diaminopimelate-alanine bonds in high-molecular-mass murein sacculi. Pbp8 is a proteolytic product of Pbp7. In E.coli there are three murein endopeptidases: two are penicillin sensitive (DacB and PbpG), the other (MepA) not. Belongs to the peptidase S11 family.