Question

The enzyme Enolase is inhibited by :

• A. Sodium fluoride
• B. Potassium oxalate
• C. EDTA
• D. None of the above

Answer 1

Answer:

A. Sodium fluoride

• Fluoride is a well-known non-competitive inhibitor of the enzyme Enolase.
• Enolase is a metalloenzyme responsible for the conversion of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP) during the process of Glycolysis.
• The inhibition occurs because fluoride ions form a complex with the magnesium ions (Mg²⁺) required by the enzyme for its catalytic activity, effectively removing the necessary cofactor.
• In clinical and laboratory settings, fluoride is often added to blood collection tubes (such as gray-top tubes) to inhibit glycolysis. This prevents blood cells from consuming glucose in the sample, ensuring accurate measurement of blood glucose levels.
• Glycolysis is the anaerobic breakdown of glucose into pyruvate. By inhibiting Enolase, fluoride effectively halts this pathway, leading to an accumulation of 2-phosphoglycerate and 3-phosphoglycerate.
• The chemical formula for the reaction catalyzed by Enolase is: 2-Phospho-D-glycerate ↔ Phosphoenolpyruvate + H₂O.