Oxacillin, through its β-lactam ring, covalently binds to penicillin-binding proteins, which are enzymes involved in the synthesis of the bacterial cell wall. This binding interaction interferes with the transpeptidation reaction and inhibits the synthesis of peptidoglycan, a prominent component of the cell wall. By decreasing the integrity of the bacterial cell wall, it is thought that oxacillin and other penicillins kill actively growing bacteria through cell autolysis.