DD-transpeptidase

A transpeptidase (EC 3.4.16.4, DD-peptidase, DD-transpeptidase, DD-carboxypeptidase, D-alanyl-D-alanine carboxypeptidase, D-alanyl-D-alanine-cleaving-peptidase, D-alanine carboxypeptidase, D-alanyl carboxypeptidase, and serine-type D-Ala-D-Ala carboxypeptidase.^[1]) is a bacterial enzyme that cross-links peptidoglycan chains to form rigid cell walls. In Gram-positive bacteria, the peptidoglycan molecules are cross-linked by a pentapeptide bridge, whereas, in Gram-negative bacteria, the peptidoglycan molecules are directly covalently bound to each other.

The antibiotic penicillin irreversibly binds to and inhibits the activity of the transpeptidase enzyme by forming a highly stable penicilloyl-enzyme intermediate. Because of the interaction between penicillin and transpeptidase, this enzyme is also known as penicillin-binding protein (PBP).

See also

• Vancomycin, an antibiotic that binds the D-ala-D-ala residues, inhibiting elongation via glycosyltransferase

References

External links

• The MEROPS online database for peptidases and their inhibitors: S11.001
• EC 3.4.16.4
• Serine-Type D-Ala-D-Ala Carboxypeptidase at the US National Library of Medicine Medical Subject Headings (MeSH)