peptidnog

Peptidoglycan is a type of molecule that forms a mesh-like structure in the cell walls of bacteria. It is composed of two main components: glycan strands and peptides. The glycan strands are made up of alternating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), which are linked by β-1,4 glycosidic bonds. These glycan strands are cross-linked by short peptides, typically containing three or four amino acids, which are attached to the NAM units. The most common peptides found in peptidoglycan are those containing the amino acids D-alanine and D-glutamate.

The structure of peptidoglycan varies among different bacterial species, but it is generally characterized by its high degree of cross-linking, which provides strength and rigidity to the cell wall. This structure is essential for maintaining the shape and integrity of bacterial cells and is a key target for many antibiotics, which disrupt the peptidoglycan synthesis or cross-linking process.

Peptidoglycan is not found in the cell walls of archaea or eukaryotes, which have different cell wall compositions. In archaea, the cell wall is typically composed of pseudomurein, while in eukaryotes, the cell wall is composed of chitin in fungi and cellulose in plants. The absence of peptidoglycan in these organisms is a key characteristic that distinguishes them from bacteria.