Molecular Classification
Peptide, Cell Wall Component
Other Names
D-Ala-D-Ala dipeptide, D-alanyl-D-alanine moiety, Peptidoglycan precursor terminus
Disease Roles
Bacterial infection

D-Alanyl-D-Alanine Overview

The D-Ala-D-Ala moiety is a dipeptide composed of two D-alanine residues. It forms the C-terminal end of the peptide stem attached to N-acetylmuramic acid (MurNAc) in peptidoglycan precursor subunits, which are essential building blocks for bacterial cell wall synthesis. It is a crucial substrate for transpeptidase enzymes, and a target for antibiotics like vancomycin.

Mechanism of Action

Vancomycin binds directly to the D-Ala-D-Ala moiety, blocking transpeptidases. β-lactam antibiotics inhibit penicillin-binding proteins (transpeptidases) that interact with D-Ala-D-Ala.

Biological Functions

Peptidoglycan biosynthesis
Cell wall cross-linking
Substrate for transpeptidases

Disease Associations

Bacterial infection

Safety Considerations

  • Development of antibiotic resistance via alteration of the D-Ala-D-Ala sequence (e.g., to D-Ala-D-Lac or D-Ala-D-Ser)

Interacting Drugs

Vancomycin
β-lactam antibiotics
Penicillin