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A cell wall polymer found in bacteria. It is a peptide cross-linked polysaccharide that forms a rigid structural scaffold around the cell.

The repeating saccharide unit is N-acetylglucosamine (NAG) / N-acetylmuramic acid (NAM), linked beta(1 -> 4).

    CH2OH           CH2OH
    |               |
    C---O       H   C----O
   /     \  |\  |  /      \
 -C   OH  C | O | C        C-
   \ /   /  H  \   \ /\   /
    C---C           C--\-C
    |   |           |  |  \
    H   NHAc        H  |   NHAc
This is cross-linked by short peptides, which have the unusual property of possesing D-amino acids. This tends to render the polymer resistant to proteases. Penicillin is a suicide inhibitor for the enzymes that cross-link the strands. Also lysozyme can cut the beta(1->4) links of the (NAG-NAM). Both of these cause the cell to lyse as the peptidoglycan breaks down.
See also: A polymer of amino sugars (mainly N-acetylglucosamine and N-acetylmuramic acid); the predominant substance in the cell wall of bacteria.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.

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