N-Acetylmuramic acid

N-Acetylmuramic acid (also known as MurNAc or NAM) is a derivative of glucosamine and a key component in the peptidoglycan layer of bacterial cell walls. It is a unique monosaccharide that is not found in eukaryotic cells, making it a target for antibiotic drugs.

Structure and Synthesis

N-Acetylmuramic acid is a monosaccharide composed of a glucose molecule with an acetyl group and a lactic acid molecule attached. The synthesis of N-Acetylmuramic acid begins with the conversion of fructose-6-phosphate to glucosamine-6-phosphate by the enzyme glutamine-fructose-6-phosphate aminotransferase. This is followed by the addition of an acetyl group to form N-acetylglucosamine-6-phosphate, and finally the addition of a lactic acid molecule to form N-Acetylmuramic acid.

Role in Bacterial Cell Walls

N-Acetylmuramic acid is a crucial component of the peptidoglycan layer in bacterial cell walls. It forms a disaccharide with N-acetylglucosamine (NAG), and these disaccharides are linked together by beta-1,4-glycosidic bonds to form a polysaccharide chain. These chains are cross-linked by short peptide chains to form the rigid peptidoglycan layer that provides structural support to the bacterial cell.

Antibiotic Target

Because N-Acetylmuramic acid is unique to bacterial cells and crucial for their survival, it is a target for antibiotic drugs. Penicillin and other beta-lactam antibiotics work by inhibiting the enzymes that cross-link the peptidoglycan chains, preventing the formation of a functional cell wall and leading to the death of the bacterial cell.

See Also

• Peptidoglycan
• N-acetylglucosamine
• Antibiotics
• Bacterial cell structure