peptidoglikann

Peptidoglycan is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria. It is a crucial component of the bacterial cell wall, providing structural support and maintaining cell shape. The structure of peptidoglycan is a long chain of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) sugar residues. These sugar chains are cross-linked by short peptide chains, which are attached to the NAM residues. The specific composition and length of these peptide chains vary between different bacterial species.

The peptidoglycan layer is essential for bacterial survival. It protects the bacterium from osmotic lysis, which is the bursting of the cell due to the influx of water. The rigid structure of the cell wall counteracts the internal turgor pressure. The thickness of the peptidoglycan layer differs between Gram-positive and Gram-negative bacteria. Gram-positive bacteria have a thick layer of peptidoglycan, while Gram-negative bacteria have a thinner layer located between the inner and outer membranes. This difference is a key factor in the Gram staining procedure, a common diagnostic tool in microbiology.

The synthesis and maintenance of peptidoglycan are targets for several antibiotics, such as penicillin. These antibiotics inhibit the enzymes responsible for the cross-linking of the peptide chains, weakening the cell wall and leading to cell death. This makes peptidoglycan a vital target for antimicrobial therapies.