Peptidoglycans (mucopeptides, glycopeptides, mureins) are the structural elements of almost all bacterial cell walls. Peptidoglycans are made up of a polysaccharide backbone consisting of alternating muramic acid (MA) and glucose amine (GA) residues in equal amounts. The walls of some Gram positive bacteria are completely dissolved by lysozyme, indicating that they are made up of GA and MA.
In other Gram positive bacteria, e.g. Staphylococcus aureus, the walls are resistant to the action of lysozyme. In Mycobacterium smegmatis the N- acetyl muramic acid residues are replaced by N-glycolymuramic acid residues.
Certain antibiotics act by inhibiting protein synthesis in bacteria, at the same time not affecting protein synthesis in the host. This is because of the differences between the 70S bacterial ribosome and the 80S eukaryote ribosome. Streptomycin acts by inhibiting protein synthesis by altering the structure of the 30S ribosomal subunit. Tetracycline inhibits protein synthesis by interfering with binding of tRNA with ribosomes.
Powar.C.B.(1999). Cell Biology