Question

the formation of glutamine from glutamate and ammonium ions requires 14.2 kJ/mol of energy input. It is driven by the hydrolysis of ATP to ADP mediated by the enzyme glutamine synthetase.

A) given that the change in Gibbs free energy for the hydrolysis of ATP is deltarG = -31 kJ/mol under the conditions prevailing in a typical cell, can the hydrolysis drive the formation of glutamine?

B)how many moles of ATP must be hydrolyzed to form 1 mol of glutamine?

Answer 1

A)

Energy required to convert 1 mole glutamine from glutamate = 14.2 KJ

_rG of hydrolysis of ATP = - 31 KJ/mol

so, energy released in the hydrolysis of 1 mole ATP = 31 KJ

Hence energy released in the hydrolysis of 1 mole of ATP is more than the energy required to form 1 mole gultamine . Therefore the hydrolysis can drive the formation of glutamine.

B)

Energy released by 1 mol ATP = 31 KJ

conversion factor = ( 1 mol ATP/31 KJ) .

Energy required to for 1 mole glutamine = 14.2 KJ

so,14.2 KJ energy will be released

= 14.2 KJ (1 mol ATP/31 KJ)

= (14.2/31) mol ATP

= 0.46 mol ATP .

Hence, 0.46 moles of ATP must by hydrolyzed to form 1 mol of glutamine .