Peptidoglycan

Peptidoglycan, also known as murein, is a substance that forms a homogeneous layer lying outside the plasma membrane in prokaryotes. It serves a structural role in bacterial cell walls, giving bacteria shape and strength, and counteracting the osmotic pressure of the cytoplasm. It is also involved in binary fission (reproduction) of the bacterial cell. Drugs such as penicillin work by interfering with the formation of the peptidoglycan layer, specifically the crosslinking enzyme transpeptidase.

Related Topics:
Substance - Plasma membrane - Prokaryote - Cell wall - Osmotic pressure - Cytoplasm - Penicillin

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The peptidoglycan layer is thicker in Gram-positive bacteria (20 to 80 nm) than in Gram-negative bacteria (7 to 8 nm), with the attachment of the S-layer. It forms around 90% of the dry weight of gram positive bacteria but only 10% of that of gram negative bacteria.

Related Topics:
Gram-positive - Bacteria - Nm - Gram-negative - S-layer

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The peptidoglycan layer in the bacterial cell wall is a lattice structure formed from linear chains of two alternating amino sugars, namely N-acetyl glucosamine (GlcNAc) and N-acetyl muramic acid (MurNAc). Each MurNAc is attached to a short (4 to 5 residues) amino acid chain. Cross-links between aminoacids in different linear amino sugar chains by an enzyme known as transpeptidase result in a 3-dimensional layer that is strong and rigid. The exact amino acid sequence and the exact overall structure vary with the bacterial species.

Related Topics:
Lattice - Sugar - N-acetyl glucosamine - N-acetyl muramic acid - Amino acid - Cross-link - Aminoacid - Transpeptidase - Species

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