Question

Which one of the following coenzymes is utilised by alanine racemase for the conversion of L-Alanine to D-Alanine?

• A. Pyridoxal phosphate
• B. Thiamine pyrophosphate
• C. Tetrahydrofolate
• D. Flavin mononucleotide

Hint:

Remember, pyridoxal phosphate (PLP) is commonly involved in amino acid metabolism and plays a crucial role in transamination and racemization reactions.

Answer 1

The Correct Option is A

Alanine racemase is an enzyme responsible for converting L-Alanine to D-Alanine, and this process requires the coenzyme pyridoxal phosphate (PLP). Pyridoxal phosphate is the active form of vitamin B6 and is involved in various enzymatic reactions, especially those related to amino acid metabolism.

Step 1: The reaction catalyzed by alanine racemase involves the interconversion of L-Alanine and D-Alanine. In this reaction, PLP serves as a cofactor. It binds to the amino acid and facilitates the transfer of the amino group between the L- and D- forms.

Step 2: The enzyme binds L-Alanine and PLP at its active site. The PLP molecule undergoes a transformation, forming a covalent bond with the amino acid. This bond allows the transfer of the amino group, which is essential for the interconversion between the L- and D- forms of alanine.

Step 3: The structure of PLP helps stabilize the transition state during the racemization process. This step is crucial for allowing the conversion of L-Alanine to D-Alanine without requiring additional energy inputs.

Thus, alanine racemase utilizes pyridoxal phosphate to facilitate the conversion of L-Alanine to D-Alanine.