Bacteria constantly reconstruct their peptidoglycan cell walls and break down portions of the cell walls as they grow and divide. Penicillin inhibits the formation of peptidoglycan cross-links in the bacterial cell wall. This is achieved by the binding of the Lactam ring of penicillin to the enzyme transpeptidase. Hence, peptidase cannot catalyse the formation of the cross-links. This produces imbalanced cell wall production and starts degradation, thereby causing the cell to rapidly die.

Uses

Penicillin is widely used in the treatment of Gram-positive bacterial infections.