Isolation of five penicillin-binding proteins fromStaphylococcus aureus

Five penicillin-binding proteins have been isolated from detergent-solubilized membranes of Staphylococcus aureus and have been separated from other membrane proteins by covalent affinity chromatography on 6-aminopenicillanic acid-Sepharose. The PBPs were resolved by electrophoresis on SDS-polyacrylamide gels and their ability to bind radioactive penicillin assayed after transfer from the polyacrylamide gel onto nitrocellulose membrane filters. Synthesis of a β-lactam antibiotic, propionylampicillin and of [2,3-3H]propionylampicillin of high specific activity greatly facilitated the assay of penicillin-binding activity.