Peptidoglykaani

Peptidoglycan is a type of polymer that forms the primary component of the cell wall in bacteria. It is a complex molecule composed of two main parts: a backbone of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) sugars, and a peptide chain that is attached to the NAM sugar. The peptide chain typically consists of four amino acids: L-alanine, D-glutamic acid, meso-diaminopimelic acid, and D-alanine. The structure of peptidoglycan varies among different bacterial species, but it is generally characterized by a cross-linked network that provides structural rigidity and protection to the bacterial cell.

The synthesis of peptidoglycan occurs in the cytoplasm and is catalyzed by a series of enzymes known as peptidoglycan biosynthetic enzymes. These enzymes work together to assemble the peptidoglycan subunits and incorporate them into the growing cell wall. The peptidoglycan layer is essential for the structural integrity and shape of bacterial cells, and it also plays a role in protecting the cell from environmental stresses and osmotic pressure.

In Gram-positive bacteria, the peptidoglycan layer is thick and forms a continuous meshwork that surrounds the entire cell. In contrast, Gram-negative bacteria have a thinner peptidoglycan layer that is located between the inner and outer membranes of the cell envelope. The outer membrane of Gram-negative bacteria contains lipopolysaccharides (LPS) and other molecules that contribute to the overall structure and function of the cell wall.

Peptidoglycan is a target for many antibiotics, as it is essential for bacterial cell wall synthesis and integrity. Antibiotics such as penicillin and vancomycin inhibit the enzymes involved in peptidoglycan synthesis, leading to the disruption of the cell wall and ultimately the death of the bacterial cell. However, the development of antibiotic resistance has become a significant concern in the treatment of bacterial infections.