D.8.3 Explain the importance of beta-lactam ring action of penicillin

The beta-lactam ring is circled in orange.


Structure of Penicillin:
  • 4 membered square ring with bond angles of 90o
  • Ring consists of 1 N atom and 3 C atoms
  • Ring is strained and so very reactive

When the beta-lactam ring comes into contact with bacteria, the ring "opens", and covalently bonds to the enzyme transpeptidase that is used to synthesize the bacterias cell wall. The enzyme's action is therefore blocked, the bacterias cell wall is weakened, and the bacterium eventually bursts.