Fluoride inhibit enzyme of which ion?
Hmm, the correct answer is probably related to a specific enzyme that's sensitive to fluoride. I remember that fluoride inhibits the enzyme enolase in glycolysis. Enolase requires Mg²+ as a cofactor. So when fluoride is present, it might interfere with Mg²+ availability, thereby inhibiting enolase. That would mean the ion is magnesium. Let me check that again.
Enolase catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate. Magnesium is a necessary cofactor here. Fluoride forms a complex with Mg²+, making it unavailable for the enzyme. So the ion in question is magnesium. Therefore, the correct answer should be magnesium. The other options might include other ions like sodium, potassium, calcium, or chloride. Let me verify if there are other enzymes inhibited by fluoride. No, the key one is enolase with Mg²+.
So the core concept is fluoride's role as an inhibitor of enolase by binding to magnesium. The correct answer is magnesium. The wrong options would be other ions that aren't directly involved in this inhibition. The clinical pearl is remembering that fluoride in antiseptics or toothpaste inhibits bacterial enolase, affecting their energy production. That's a high-yield fact for exams.
**Core Concept**
Fluoride acts as a competitive inhibitor of the glycolytic enzyme **enolase**, which requires **Mg²⁺** as a cofactor. Fluoride binds to free Mg²⁺, preventing its interaction with enolase and disrupting ATP production in bacteria and some eukaryotic cells.
**Why the Correct Answer is Right**
Enolase catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate in glycolysis. This reaction depends on Mg²⁺ as a cofactor. Fluoride forms a stable complex with Mg²⁺, rendering it unavailable for enolase activity. This mechanism is exploited in bacterial inhibition (e.g., in microbiological transport media) and as a preservative in blood samples.
**Why Each Wrong Option is Incorrect**
**Option A:** Sodium (Na⁺) is not a cofactor for enolase and is not targeted by fluoride.
**Option B:** Potassium (K⁺) is irrelevant to enolase inhibition; it plays no role in this pathway.
**Option C:** Calcium (Ca²⁺) is unrelated to enolase activity and fluoride’s mechanism.
**Clinical Pearl / High-Yield Fact**
Remember the **"Fluoride-Mg²⁺-Enolase" triad**: Fluoride inhibits enolase by sequestering Mg²⁺. This is why fluoride is used in blood collection tubes to prevent glycolysis and preserve glucose levels. Avoid confusing it with other ions like K⁺ or Na⁺, which are not involved in this inhibition.
**Correct Answer: C