Question

The least abundant amino acid in human proteins is:

• A. \( \text{Leucine} \)
• B. \( \text{Lysine} \)
• C. \( \text{Cysteine} \)
• D. \( \text{Tyrosine} \)

Hint:

Cysteine contributes to protein stability by forming disulfide bridges, which help maintain structural integrity.

Answer 1

The Correct Option is C

Cysteine is the least abundant amino acid in human proteins due to its highly reactive thiol (-SH) group. It plays a critical role in forming disulfide bonds that stabilize protein structure but is not frequently incorporated into protein sequences. Its low abundance is partly due to its sensitivity to oxidation and modification in cellular environments.