Question
Which one among the following essential amino acids is usually the “limiting” amino acid in most of the pulses?
| A. |
Lysine
|
| B. |
Methionine
|
| C. |
Threonine
|
| D. |
Valine
|
Show Answer
|
Correct Answer » B
Explanation
|
|
- A limiting amino acid is the essential amino acid present in the smallest amount relative to the body’s requirement.
- Its deficiency limits protein synthesis even if all other essential amino acids are available in adequate amounts.
- Different food proteins have different limiting amino acids.
- Pulses (legumes)are rich in:
- Lysine
- Leucine
- Isoleucine
- However, they are deficient in sulfur-containing amino acids, especially:
- Methionine (primary limiting amino acid)
- Cysteine (conditionally essential)
- Therefore, methionine is the limiting amino acid in most pulses.
Why Other Options are Incorrect
A. Lysine
- Pulses are rich in lysine.
- Lysine is the limiting amino acid in cereals, not pulses.
C. Threonine
- Threonine is adequately present in most pulses.
- It is not the limiting amino acid.
D. Valine
- Valine is a branched-chain essential amino acid.
- It is generally present in adequate amounts in pulses.
