​The standard free energy (kJ mol⁻¹) of hydrolysis of glucose-1-phosphate is​

Correct option is B

Explanation:

• The hydrolysis of glucose-1-phosphate (G1P) releases free energy as the phosphate group is cleaved, forming glucose and inorganic phosphate (Pi).
• The standard free energy change (ΔG°') for this reaction has been experimentally determined to be approximately -20.9 kJ/mol.
• The negative value indicates that the reaction is spontaneous and thermodynamically favorable.
• This free energy release is less than ATP hydrolysis (-30.5 kJ/mol) but still significant for cellular energy metabolism.
• Glucose-1-phosphate is an important intermediate in glycogen metabolism, where it is converted to glucose-6-phosphate by the enzyme phosphoglucomutase.

Thus, the correct value for the standard free energy of hydrolysis of glucose-1-phosphate is -20.9 kJ/mol (option 2).

Information Booster

1. Glucose-1-phosphate (G1P) is a phosphorylated sugar involved in glycogen breakdown and synthesis.
2. The hydrolysis of G1P releases -20.9 kJ/mol, making it a moderate-energy phosphate compound.
3. G1P is converted to glucose-6-phosphate (G6P) by phosphoglucomutase, allowing it to enter glycolysis.
4. ATP hydrolysis (-30.5 kJ/mol) releases more energy than G1P hydrolysis, which is why ATP is the primary energy currency.
5. The phosphate bond in G1P is not as high-energy as ATP but still provides sufficient free energy for biochemical reactions.
6. G1P is utilized in glycogenesis, where it is activated by UDP-glucose pyrophosphorylase before being added to glycogen.
7. In glycogenolysis, glycogen phosphorylase cleaves glycogen to produce G1P, bypassing the need for ATP investment.

Additional Information

• Option (1) -40.3 kJ/mol: Too high; closer to ATP hydrolysis.
• Option (2) -35.8 kJ/mol: Incorrect; similar to ATP hydrolysis but not for G1P.
• Option (3) -7.7 kJ/mol: Too low; insufficient to describe the energy release from G1P hydrolysis.