Question 1: Fluoride, used in the collection of blood samples, inhibits which enzyme?
- A. Enolase (Correct Answer)
- B. Glucokinase
- C. Glucose-6-phosphatase
- D. Hexokinase
Explanation: ***Enolase***
- Fluoride is a potent inhibitor of **enolase**, an enzyme in the **glycolytic pathway**.
- Inhibition of enolase prevents the conversion of **2-phosphoglycerate** to **phosphoenolpyruvate**, thereby halting glycolysis in collected blood samples.
*Glucokinase*
- Glucokinase is an enzyme primarily found in the **liver** and **pancreatic beta cells** that phosphorylates glucose.
- Fluoride does not directly inhibit glucokinase; its primary site of action for preventing glycolysis in blood samples is enolase.
*Glucose-6-phosphatase*
- This enzyme is crucial for **glucose production** in the liver and kidneys, facilitating the dephosphorylation of **glucose-6-phosphate** to glucose.
- Fluoride does not specifically target glucose-6-phosphatase as its mechanism for preventing glycolysis.
*Hexokinase*
- Hexokinase catalyzes the first step of glycolysis, phosphorylating **glucose to glucose-6-phosphate**.
- While essential for glycolysis, hexokinase is not the primary target of fluoride's inhibitory action in blood collection, which specifically aims to stop the entire pathway further downstream at enolase.