|
The more negative 
for ATP hydrolysis derives primarily from its more exothermic nature
(neg.  ).
The greater exothermicity associated with ATP hydrolysis is a consequence
of the smaller input of energy (enthalpy) required to rupture the
weaker phosphoanhydride linkage in comparison with the phosphodiester
link in DNA:
|
|
(hydrolysis)
(kJ/mol)
|
|
ATP + H2O --> ADP + Pi
|
-24.2
|
|
DNA + H2O --> 5’DNA + 3’DNA
|
-12.0
|
so that reversing the 2nd reaction in the direction of DNA formation:
|
ATP + H2O --> ADP + Pi
|
-24.2
|
|
5’DNA + 3’DNA --> DNA + H2O
|
12.0
|
results in an overall exothermic process if the condensation of
the 2 DNA fragments can be coupled to the ATP hydrolysis reaction:
|
5’DNA + 3’DNA + ATP --> DNA + ADP + Pi
|
-11.8
|
|
