Antibiotics and macromolecular synthesis in microsomes and mitochondria: II. Antibiotics acting in a different manner in microsomes and mitochondria

Abstract

Effects of antibiotics were assayed on protein- and glycoprotein-synthesizing systems in isolated mitochondria and microsomes over a 10 5 concentration range. The antibiotic effects on glycoprotein synthesis were measured in isolated sterile rat liver and cortical intraneural mitochondria, while the effects on protein synthesis were measured on isolated sterile rat liver and cortical intraneural mitochondria and rat liver microsomes. Antimycin C only inhibited protein synthesis in the liver and brain mitochondria, while chloramphenicol and rutamycin inhibited protein and glycoprotein synthesis in rat liver and brain mitochondria. Erythromycin and kanamycin slowed macromolecular biosynthesis in all systems, but mitochondria were more sensitive to the inhibitory action. In general, the effects of these antibiotics caused a greater amount of inhibition of protein and glycoprotein synthesis in the cortical intraneural mitochondrial system than in the liver mitochondrial system. The protein synthesis was inhibited to a greater extent than the glycoprotein synthesis in both the liver and cortical intraneural mitochondrial systems. Cycloheximide and valinomycin affected macromolecular synthesis in mitochondria and microsomes, but their primary action was the inhibition of microsomal protein synthesis. Lincomycin and neomycin only inhibited microsomal protein synthesis.