Fluoride which is used in the collection of blood samples for glucose estimation inhibits whch of the following enzyme?
**Core Concept**
Fluoride is a chemical inhibitor used in the laboratory setting to prevent glycolysis, the breakdown of glucose in the blood sample. This is crucial for accurate glucose estimation, as glycolysis can lead to falsely low glucose readings.
**Why the Correct Answer is Right**
Fluoride specifically inhibits the enzyme **hexokinase**, which is the first enzyme in the glycolytic pathway. Hexokinase catalyzes the conversion of glucose to glucose-6-phosphate, the rate-limiting step in glycolysis. By inhibiting hexokinase, fluoride prevents the breakdown of glucose, allowing for accurate measurement of glucose levels in the blood sample.
**Why Each Wrong Option is Incorrect**
* **Option A:** Fluoride does not inhibit **pyruvate kinase**, another enzyme in the glycolytic pathway. Pyruvate kinase is involved in the conversion of phosphoenolpyruvate to pyruvate, but it is not the primary target of fluoride inhibition.
* **Option B:** Fluoride does not inhibit **aldolase**, an enzyme involved in the conversion of fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. While aldolase is an important enzyme in glycolysis, it is not the primary target of fluoride inhibition.
* **Option D:** Fluoride does not inhibit **phosphofructokinase**, an enzyme involved in the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. Phosphofructokinase is a key regulatory enzyme in glycolysis, but it is not the primary target of fluoride inhibition.
**Clinical Pearl / High-Yield Fact**
Fluoride is a common inhibitor used in laboratory settings to prevent glycolysis in blood samples. It is essential to note that fluoride is not suitable for all types of glucose estimations, and other inhibitors may be used depending on the specific laboratory protocol.
**Correct Answer: C. Hexokinase**