ULTRASTRUCTURAL-LOCALIZATION OF PENICILLIN-BINDING SITES IN STAPHYLOCOCCUS-AUREUS USING PENICILLIN G-BSA-GOLD

Penicillin G (PcG) conjugated to bovine serum albumin (BSA) was found to retain antibacterial activity against Staphylococcus aureus as judg ed by growth inhibition and by ultrastructural analyses of the PcG-BSA -treated bacterium. Using the PcG-BSA conjugated to colloidal gold, bi nding sites of PcG were localized in S. aureus with electron microscop y using a postembedding labeling technique, To our surprise, labeling was observed both on the cell wall and in the cytoplasm of S. aureus. A part of the labeling observed may be attributed to penicillin-bindin g proteins (PBPs) or their precursors. Also there may be other molecul es which bind with PcG in the cell wall and cytoplasm of S. aureus.