Question

1,3 BPG and PEP are higher in energy compared to ATP. Why is this important?

Answer 1

ATP is produced by two substrate-level phosphorylation reactions in the glycolysis.

They are,

i. PEP + ADP ---------> Pyruvate + ATP

ii. 1,3-BPG + ADP --------> 3-PG + ATP

dG of PEP hydrolysis = -14.8 kcal/mol

dG of 1,3-BPG hydrolysis = -11.8 kcal/mol

dG of ATP hydrolysis = -7.3 kcal/mol

According to thermodynamic principles, 100% energy conversion can not occur. There is always energy loss.

Hence, the production of ATP is coupled to the hydrolysis of high energy compounds that release more energy than ATP hydrolysis.