Transpeptidase

Transpeptidase is an enzyme present in almost all bacteria. It is used to create cross-links (covalent bonds) between peptidoglycan molecules in the bacterial cell wall. Firstly, the enzyme binds to the D-Ala-D-Ala end of the peptidoglycan polysaccharide, releasing a D-Alanine residue as it does. Next, the enzyme connects an adjacent peptidoglycan to the original one using covalent bonds between the polysaccharide region of each molecule. Transpeptidase is inhibited by beta-lactam antibiotics, such as the group of penicillins.