What is the overall ΔG for the combined glucose phosphorylation and ATP hydrolysis?

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Multiple Choice

What is the overall ΔG for the combined glucose phosphorylation and ATP hydrolysis?

Energy coupling lets ATP hydrolysis drive the phosphorylation of glucose. The overall ΔG for glucose plus ATP forming glucose-6-phosphate and ADP is the sum of the energy from ATP hydrolysis and the energy required to transfer a phosphate to glucose. ATP hydrolysis releases about -30.5 kJ/mol. The phosphate transfer to glucose that yields glucose-6-phosphate requires about +13.8 kJ/mol. Adding them gives -30.5 + 13.8 = -16.7 kJ/mol. So the combined process has a negative ΔG of about -16.7 kJ/mol, meaning it proceeds spontaneously under standard conditions. This value sits between the two extremes and explains why the reaction is favorable but not as exergonic as ATP hydrolysis alone.

Energy coupling lets ATP hydrolysis drive the phosphorylation of glucose. The overall ΔG for glucose plus ATP forming glucose-6-phosphate and ADP is the sum of the energy from ATP hydrolysis and the energy required to transfer a phosphate to glucose. ATP hydrolysis releases about -30.5 kJ/mol. The phosphate transfer to glucose that yields glucose-6-phosphate requires about +13.8 kJ/mol. Adding them gives -30.5 + 13.8 = -16.7 kJ/mol. So the combined process has a negative ΔG of about -16.7 kJ/mol, meaning it proceeds spontaneously under standard conditions. This value sits between the two extremes and explains why the reaction is favorable but not as exergonic as ATP hydrolysis alone.

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