Glycopeptides like vancomycin act by binding to the terminal
D-ala-D-ala of
the pentapeptidyl-glycosyl peptidoglycan intermediates
(nascent
peptidoglycan pentapeptide). This mechanism prevents their
incorporation into
the peptidoglycan chain by blocking the transpeptidation step in
cell wall
biosynthesis (transglycosylase). Because vancomycin cannot pass
through theouter membrane of the gram negative bacteria, it is just
limited to gram-positive
microorganisms.
Resistance: terminal d-alanine of d-ala-d-ala replaced by
d-lactate.
: Results to loss of critical H-bond that facilitates binding
of
