penicillin binding

Definition

Target type: molecularfunction

Binding to penicillin, an antibiotic that contains the condensed beta-lactamthiazolidine ring system. [GOC:ai]

Penicillin binding is a crucial step in the inhibition of bacterial cell wall synthesis. Penicillins are β-lactam antibiotics that target the bacterial enzyme transpeptidase, also known as penicillin-binding protein (PBP). Transpeptidases are responsible for the final step in peptidoglycan synthesis, a complex polymer that forms the rigid cell wall of bacteria. This process involves the formation of cross-links between peptide chains in peptidoglycan, providing structural integrity to the cell wall.

Penicillin mimics the natural substrate of transpeptidases, the D-alanyl-D-alanine dipeptide. It binds to the active site of the enzyme, forming a stable covalent complex. This binding event inhibits the transpeptidases activity, preventing the formation of cross-links in peptidoglycan. As a result, the bacterial cell wall becomes weakened, making the bacteria susceptible to osmotic lysis and ultimately leading to cell death.

The mechanism of penicillin binding involves a nucleophilic attack by the active site serine residue of the transpeptidase on the β-lactam ring of penicillin. This attack opens the β-lactam ring, forming a stable covalent adduct between the penicillin molecule and the enzyme. This covalent complex is highly stable and effectively inactivates the transpeptidase, preventing its further activity.

Penicillin binding is a highly specific process, with different penicillin derivatives exhibiting varying affinities for different transpeptidases. This specificity allows for the development of penicillin-based antibiotics that target specific bacterial species and minimize the impact on the host.'
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Proteins (1)

Compounds (1)