What is atp coupling?

1 Answer
Ernest Z.
Jun 25, 2015

"ATP" coupling is the use of the free energy released by the hydrolysis of "ATP" to drive a thermodynamically unfavourable reaction.

Explanation:

For example, the conversion of glucose to glucose-6-phosphate by the enzyme hexokinase is thermodynamically unfavourable, with ΔG = "+14.3 kJ/mol".

The hydrolysis of "ATP" to "ADP" is a highly favourable process, with ΔG = "-30.5 kJ/mol".

The reactions are

"glucose " + cancel("P"_i) → "glucose-6-P" + cancel("H"_2"O"); ΔG = "+14.3 kJ/mol"

"ATP" + cancel("H"_2"O") → "ADP" + cancel("P"_i); ΔG = "-30.5 kJ/mol"

bar("glucose " + "ATP" stackrel("hexokinase")(→) "glucose-6-P" + "ADP"); ΔG = "-16.2 kJ/mol"

The coupled reaction has a negative free energy, so the process is thermodynamically favourable.

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