Q19 / 200 · MHT CET - Medical 2026 (25 April Shift 2) · Biology
Which one of the following is the activator for enzyme hexokinase in glycolysis?
- A$\text{Mn}^{++}$
- Correct answerB$\text{Mg}^{++}$
- C$\text{Mo}^{++}$
- D$\text{Zn}^{++}$
Solution
Hexokinase is the first enzyme in the glycolysis pathway, which catalyzes the phosphorylation of glucose to glucose-6-phosphate using ATP.
The true substrate for hexokinase is not free ATP, but the $\text{Mg}^{++}$-ATP complex. The $\text{Mg}^{++}$ ion shields the negative charges of the phosphate groups in ATP, making the terminal phosphorus atom an easier target for nucleophilic attack by the hydroxyl group of glucose.
Therefore, $\text{Mg}^{++}$ acts as an essential cofactor and activator for the enzyme hexokinase.
Answer: $\text{Mg}^{++}$
The true substrate for hexokinase is not free ATP, but the $\text{Mg}^{++}$-ATP complex. The $\text{Mg}^{++}$ ion shields the negative charges of the phosphate groups in ATP, making the terminal phosphorus atom an easier target for nucleophilic attack by the hydroxyl group of glucose.
Therefore, $\text{Mg}^{++}$ acts as an essential cofactor and activator for the enzyme hexokinase.
Answer: $\text{Mg}^{++}$
Hence, the correct answer is option: 'B'.