Fluoride, used in the collection of blood samples for glucose estimation, inhibits the enzyme
**Core Concept**
Fluoride is a well-known inhibitor of glycolysis, specifically targeting the enzyme responsible for the conversion of glucose to fructose-1,6-bisphosphate in the glycolytic pathway. This enzyme is crucial for glucose metabolism in red blood cells.
**Why the Correct Answer is Right**
The correct enzyme inhibited by fluoride is **Glucose-6-phosphate Dehydrogenase (G6PD)**, although this is not the direct answer choice here. However, the correct answer is actually **Hexokinase**, which is the enzyme that catalyzes the first step of glycolysis, converting glucose to glucose-6-phosphate. Fluoride inhibits hexokinase by binding to the enzyme and preventing the transfer of a phosphate group to glucose, thus halting glycolysis. This inhibition is particularly significant in red blood cells, which lack the enzyme glucose-6-phosphate dehydrogenase (G6PD).
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the inhibition of glycolysis by fluoride.
* **Option B:** This option is not directly related to the action of fluoride on glycolytic enzymes.
* **Option D:** This option is incorrect as fluoride does not inhibit this enzyme.
**Clinical Pearl / High-Yield Fact**
Fluoride inhibits glycolysis by targeting hexokinase, which is essential for glucose metabolism in red blood cells. Knowing this fact can help you understand the importance of fluoride in preventing glycolysis and its implications in medical procedures like blood glucose estimation.
**Correct Answer: B. Hexokinase**