Question

The first 5C dicarboxylic acid in Krebs' cycle which is used in nitrogen metabolism is

• A. OAA
• B. Citric acid
• C. $\alpha$-ketoglutaric acid
• D. Acetyl coenzyme A

Answer 1

The correct option is C $\alpha$-ketoglutaric acid

The first 5 carbon dicarboxylic acid in Krebs' cycle is $\alpha$-ketoglutaric acid. The $\alpha$-ketoglutarate that accumulates when $\alpha$-ketoglutarate dehydrogenase is inhibited can be used in nitrogen metabolism as a precursor for several amino acids and the purine bases.

$\alpha -ketoglutarate\to Glutamate\to Otheraminoacids\to Purines$

$\alpha$-ketoglutarate of Krebs' cycle produces an important amino acid called glutamate on amination.

So the correct answer is '$\alpha$-ketoglutaric acid'.