These agents retard or arrest protein synthesis by interacting with essential reaction components in multistep ribosome-catalyzed processes. Cycloheximide effectively inhibits eukaryotic protein synthesis on cytoplasmic ribosomes, at 1 mg/mL resulting in 70–75% inhibition for cellfree translation, whereas 30 mg/mL almost totally blocks intracellular protein synthesis. Chloramphenicol blocks the peptidyltransferase reaction, but DNA synthesis can also be reduced by this inhibitor. Other protein synthesis inhibitors include: a-amino-b-butyric acid (an analogue of valine); aurintricarboxylic acid (an inhibitor of initiation at 50 mM); 7- azatryptophan (a tryptophan analogue that blocks bacteriophage synthesis); azetidine-2-carboxylic acid (a four-membered ring analogue of proline that can be incorporated into bacterial proteins); canavanine (an arginine analogue that inhibits bacterial protein synthesis); emetine (binds to the 40S eukaryotic ribosome and inhibits translocation); erythromycin (bacterial protein synthetase inhibitor); ethionine (a methionine analogue that inhibits bacterial protein synthesis); 5-fluorotryptophan; 6-fluorotryptophan; methyltryptophan; fusidic acid; kasugamycin; 7-methylguanosine 5′-phosphate; w-methyllysine; O-methylthreonine; norleucine; pactamycin; puromycin (a potent inhibitor of prokaryotic and eukaryotic protein synthesis); selenomethionine; sparsomycin; streptomycin; tetracycline antibiotics; and tryptazan.
