Question

Which of the following inhibits protein synthesis by binding to $ 50\,S $ ribosome?

• A. Tetracyclin
• B. Streptomycin
• C. Erythromycin
• D. Penicillin

Answer 1

The Correct Option is C

To solve this question, we need to identify which of the provided antibiotics inhibit protein synthesis by binding specifically to the 50S subunit of the ribosome.

• Tetracycline: Tetracycline works by binding to the 30S ribosomal subunit, not the 50S subunit. It prevents the attachment of the aminoacyl-tRNA to the ribosomal acceptor (A) site.
• Streptomycin: This antibiotic binds to the 30S ribosomal subunit as well and causes misreading of mRNA, inhibiting protein synthesis at this smaller subunit.
• Erythromycin: Erythromycin specifically binds to the 50S ribosomal subunit. It inhibits protein synthesis by preventing the exit of the growing polypeptide chain, effectively blocking peptide elongation.
• Penicillin: It is not involved in protein synthesis inhibition; instead, it inhibits the synthesis of bacterial cell walls by targeting peptidoglycan layers.

The correct answer is therefore Erythromycin, as it directly binds to the 50S ribosomal subunit, inhibiting protein synthesis by preventing elongation of the polypeptide chain.