Category: catabolism
Bacterial 70S ribosome (30S + 50S) is the major antibiotic target — selective toxicity arises from the eukaryotic 80S ribosome's structural differences (40S + 60S). 30S inhibitors: tetracyclines block aminoacyl-tRNA A-site loading (bacteriostatic); aminoglycosides bind 16S rRNA → mistranslation + membrane permeabilization (bactericidal). 50S inhibitors: macrolides + ketolides bind 23S rRNA peptidyl-transferase loop → premature peptide chain release (bacteriostatic, partly bactericidal at high conc); lincosamides (clindamycin) bind near macrolide site → cross-resistance via MLSb mechanism; oxazolidinones (linezolid) prevent 70S initiation complex assembly; chloramphenicol blocks peptidyltransferase. Aminoglycoside-induced ototoxicity + nephrotoxicity reflects accumulation in cochlear hair cells + renal tubular cells.