Tetracycines - The tetracyclines are broad spectrum antibiotics which inhibit the growth of both gram positive and gram negative bacteria. They are also effective against rickettsiae, mycoplasmas and some of the larger viruses.
The tetracyclines inhibit protein biosynthesis on both 70S and 80S ribsomes. They are, however, more effective against intact prokaryote cells than against eukaryote cells. All tetracyclines are produced by streptomycetes. They inhibit the binding of AA-tRNA to the A-site of ribosomes in vitro and in vivo. The binding of f-Met tRNA to ribosomes is about one-tenth as sensitive to tetracycline as the binding of other AA-tRNAs. Reports on the effect of tetracycline on peptide bond formation and inhibition of initiation are contradictory.
