Question:
Which element is required by phosphofructokinase?
Which element is required by phosphofructokinase?
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Kinases use ATP as the Mg-ATP complex - which metal?
Updated On: Jun 24, 2026
- Magnesium
- Inorganic phosphate
- Manganese
- Copper
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The Correct Option is A
Solution and Explanation
Step 1: Phosphofructokinase-1 (PFK-1) is the rate-limiting enzyme of glycolysis, transferring a phosphate from ATP to fructose-6-phosphate to make fructose-1,6-bisphosphate.
Step 2: Like essentially all kinases that use ATP, PFK requires magnesium. The true substrate is the Mg-ATP complex, because magnesium neutralises the negative charge on the phosphate groups and positions ATP for phosphoryl transfer.
Step 3: Structural studies show the bound magnesium ion bridges the phosphoryl groups of the products (ADP and fructose-1,6-bisphosphate) in the closed state, confirming its catalytic role.
Step 4: The other options do not fit: inorganic phosphate is not the required cofactor for this step, while manganese and copper are not the physiological metal cofactor of PFK. Hence the answer is magnesium.
Step 2: Like essentially all kinases that use ATP, PFK requires magnesium. The true substrate is the Mg-ATP complex, because magnesium neutralises the negative charge on the phosphate groups and positions ATP for phosphoryl transfer.
Step 3: Structural studies show the bound magnesium ion bridges the phosphoryl groups of the products (ADP and fructose-1,6-bisphosphate) in the closed state, confirming its catalytic role.
Step 4: The other options do not fit: inorganic phosphate is not the required cofactor for this step, while manganese and copper are not the physiological metal cofactor of PFK. Hence the answer is magnesium.
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