Glycopeptides synthesis and antibacterial activity
The glycopeptides vancomycin and teicoplanin are complex heterocyclic molecules consisting of a multi-peptide backbone to which are attached various substituted sugars. These compounds bind to acyl-D-alanyl-D-alanine in peptidoglycan, thereby preventing the addition of new building blocks to the growing cell wall (Figure 1).
Figure 1. Binding site of glycopeptides to peptidoglycan.
Glycopeptides do not penetrate the
external membrane of Gram-negative bacteria, so their spectrum of activity is
limited to Gram-positive organisms. Acquired resistance is growing with
enterococci and C. difficile being now widely prevalent and staphylococci
exhibiting reduced susceptibility. Avoparcin, a glycopeptide formerly used in
animal husbandry has been implicated in promoting resistance in enterococci, but
human use of glycopeptides is equally important. Some Gram-positive genera,
including Lactobacillus spp., Pediococcus spp., and Leuconostoc
spp. are inherently resistant to glycopeptides, but fortunately these
organisms are seldom implicated in disease.
Mechanism of Action
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