Which antibiotic is a known inhibitor of the 50S ribosomal subunit?

Which antibiotic is a known inhibitor of the 50S ribosomal subunit?

• A. Streptomycin
• B. Tetracycline
• C. Erythromycin
• D. Chloramphenicol

Answer: (D)

Bacterial protein synthesis can be blocked by antibiotics that bind to the ribosome’s subunits. The large 50S subunit houses the peptidyl transferase center, which forms peptide bonds between amino acids during elongation. Chloramphenicol binds to this 50S center and directly inhibits peptidyl transferase, preventing peptide bond formation and stopping protein synthesis. This makes it a classic and well-established 50S inhibitor, which is why it fits the question’s requirement. Streptomycin and tetracycline act on the 30S subunit, disrupting initiation and tRNA binding, while erythromycin also targets the 50S but by a different mechanism (blocking translocation). The key point is that chloramphenicol’s action on the peptidyl transferase center is the defining reason it’s identified as a 50S inhibitor in this context.

Bacterial protein synthesis can be blocked by antibiotics that bind to the ribosome’s subunits. The large 50S subunit houses the peptidyl transferase center, which forms peptide bonds between amino acids during elongation. Chloramphenicol binds to this 50S center and directly inhibits peptidyl transferase, preventing peptide bond formation and stopping protein synthesis. This makes it a classic and well-established 50S inhibitor, which is why it fits the question’s requirement.

Streptomycin and tetracycline act on the 30S subunit, disrupting initiation and tRNA binding, while erythromycin also targets the 50S but by a different mechanism (blocking translocation). The key point is that chloramphenicol’s action on the peptidyl transferase center is the defining reason it’s identified as a 50S inhibitor in this context.