Q.26
Which one of the following DOES NOT inhibit protein biosynthesis?
Options:
(A) Puromycin
(B) Chloramphenicol
(C) Cycloheximide
(D) Oligomycin
Protein biosynthesis inhibitors target translation at ribosomes, crucial for antibiotic development and biotech research. This question distinguishes ribosomal inhibitors from mitochondrial inhibitors in molecular biology exams.
The correct answer is (D) Oligomycin, as it specifically blocks ATP synthase in oxidative phosphorylation, not protein synthesis machinery.
Why (D) Oligomycin Does NOT Inhibit Protein Synthesis
Oligomycin binds F₀ subunit of ATP synthase, preventing proton flow and ATP production in mitochondria. While ATP depletion indirectly affects energy-demanding translation, it doesn’t directly target ribosomes, mRNA, tRNA, or translation factors—unlike options A-C.
Explanation of All Options
Each compound’s primary target determines its classification:
-
(A) Puromycin
Inhibits both prokaryotic/eukaryotic translation. Mimics aminoacyl-tRNA, enters A-site, forms peptidyl-puromycin, causing premature chain termination. -
(B) Chloramphenicol
Bacterial-specific 50S ribosome inhibitor. Blocks peptidyl transferase activity, preventing peptide bond formation during elongation. -
(C) Cycloheximide
Eukaryotic-specific 60S ribosome inhibitor. Blocks translocation step by binding E-site, preventing tRNA movement. -
(D) Oligomycin
Does NOT inhibit protein synthesis. Targets mitochondrial ATP synthase F₀ subunit, blocking oxidative phosphorylation—not ribosomes.
Quick Mechanism Comparison Table
| Option | Compound | Target | Protein Synthesis Inhibition? | Specific Action |
|---|---|---|---|---|
| A | Puromycin | Ribosome A-site | Yes | Premature termination |
| B | Chloramphenicol | Bacterial 50S | Yes | Peptidyl transferase block |
| C | Cycloheximide | Eukaryotic 60S | Yes | Translocation block |
| D | Oligomycin | ATP synthase F₀ | No | Oxidative phosphorylation |
Biotech relevance: Distinguishing direct vs indirect inhibitors critical for cell culture, recombinant protein production. Oligomycin used in mitochondrial studies, not translation research. Remember: ribosome targets = translation inhibitors; energy metabolism targets ≠ translation inhibitors.
