Question

Statement I: Diphthamide is a modified amino acid present in the elongation factor 2.
Statement II: It prevents translocation of the growing polypeptide chain.
Choose the most appropriate answer from the options given below:

• A. Statement I is correct and Statement II is incorrect
• B. Statement II is correct and Statement I is incorrect
• C. Statement I and Statement II both are correct
• D. Statement I and Statement II both are incorrect

Hint:

Diphthamide: modified amino acid in eEF2.
Target of diphtheria toxin.
Prevents translocation during protein synthesis.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Diphthamide is a unique modified amino acid.
It is found in eukaryotic elongation factor 2 (eEF2).

Step 2: Key Formula or Approach:
No specific formula.
Need to understand the role of diphthamide.

Step 3: Detailed Explanation:
Diphthamide is a modified histidine residue found in eEF2.
It is a post-translationally modified amino acid.
Thus, Statement I is correct.
Diphthamide is the target of diphtheria toxin.
The toxin ADP-ribosylates diphthamide.
This modification prevents translocation of the polypeptide chain.
Thus, Statement II is also correct.
Therefore, both statements are correct.

Step 4: Final Answer:
Both Statement I and Statement II are correct.
Hence, the correct option is (C).