Question

Which of the following statements is true about the Citrate?

(A). It is a secondary alcohol
(B). It is a chiral molecule
(C). It is formed by Claisen condensation reaction
(D). It is prochiral and a tertiary alcohol

Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (C) and (D) only.
• C. (A) and (C).
• D. (B) and (C) only.

Hint:

Citrate's prochirality explains why the asymmetric enzyme aconitase can convert an achiral molecule into the chiral molecule isocitrate.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Citrate is a symmetrical tricarboxylic acid intermediate in the Krebs (Citric Acid) cycle. Understanding its chemical structure helps clarify its stereochemical behavior in metabolic reactions.

Step 2: Detailed Explanation:
- (A) is false because the central carbon of citrate (which carries the hydroxyl group) is bonded to three other carbons. This makes it a tertiary alcohol, not a secondary alcohol.
- (B) is false because citrate is a symmetric molecule with no chiral carbon center, making it an achiral molecule in solution.
- (C) is true because citrate is formed in the first step of the Krebs cycle by condensing acetyl-CoA and oxaloacetate. This synthesis is catalyzed by citrate synthase and proceeds via a Claisen-type condensation.
- (D) is true because, although achiral, citrate is "prochiral."
Asymmetry in the active site of the enzyme aconitase allows it to distinguish between the two identical-looking carboxymethyl (\(\text{-CH}_2\text{COOH}\)) arms, reacting specifically with only one of them.
Therefore, only statements (C) and (D) are correct.

Step 3: Final Answer:
Hence, the correct option is (B).