Question

The reaction to form a peptide bond between an alanine molecule and a glycine molecule has ∆g = 29 kj/mol at 37 ◦c. this bonding reaction is coupled to the hydrolysis of one atp molecule, which has ∆g = −57 kj/mol. what is ∆gtotal for the coupled reaction?

Answer 1

The total free energy change (Δg total) for the coupled reaction of peptide bond formation and ATP hydrolysis is calculated by adding the Δg of the peptide bond formation (29 kJ/mol) to the Δg of ATP hydrolysis (-57 kJ/mol), which results in Δg total being -28 kJ/mol.

Step-by-step explanation:

The student is asking to calculate the Δg total for the coupled reaction of the peptide bond formation between an alanine molecule and a glycine molecule, which has a free energy change (Δg) of 29 kJ/mol, and the hydrolysis of one ATP molecule, which has a Δg of -57 kJ/mol.

To calculate the total free energy change of the coupled reactions, one simply adds the individual Δg values together: Δgtotal = Δgreaction + ΔgATP hydrolysis = 29 kJ/mol + (-57 kJ/mol) = -28 kJ/mol.

The coupling of these reactions enables the energetically unfavorable peptide bond formation to proceed, as the energy released from ATP hydrolysis is used to drive the reaction forward.