ATP hydrolysis..

1. HYDROLYSIS OF ATP
Presented to :- Dr. Rajesh Kumar
Presented By :- Manish Kumar
Roll No. 4857
M.Sc. Chemistry(4th sem)
Practical code :- CH-525
Date :- 15 June, 2021

2. ATP
Components :-
1. Adenine : nitrogenous Base
2. Ribose : pentose sugar
3. Phosphate group : chain of 3
 ATP is primary and universal carrier of chemical energy in the cell.
Phosphate group
ribose sugar
phospoester
linkage
O
O
OH
OH
P
O
OH
P
O
O
OH
O
H
OH
O
O
P
H
N
N
N
N
NH2
H
C1-N9 glycosidic linkage
adenine
ATP (Adenosine Triphosphate)

3. Hydrolysis of ATP
 ATP on hydrolysis gives ADP (adenosine diphosphate) and Pi (inorganic phosphate).
 On hydrolysis ATP separates one of the three negatively charged phosphates and thus
relieves of some the electrostatic repulsion in ATP.
 Hydrolysis of ATP is highly exergonic process i.e. ∆G = -30.5 KL/mol.
 The molecule is kinetically stable at pH=7 because the activation energy for hydrolysis is
relatively high.
ATP4- + H2O ADP3- + Pi
2- + H+
DG0 = -30.5 KJ/mol

4. The Free Energy Change for ATP Hydrplysis is Large
and negative:
1. The charge separation that results from hydrolysis relieves
electrostatic repulsion among the four negative charges on ATP.
2. The product inorganic phosphate (Pi) is stabilized by formation of
resonance hybrid and hydrogen ion is not permanently associated
with any one of the oxygen.
3. The Product ADP immediately ionizes, releasing a proton into of
very low [H+](pH=7).
4. ATP hydrolysis is the greater degree of solvation of the product Pi
and ADP relative to ATP, which further stabilizes the products
relative to the reactants.
2-

5. O
–
O
–
O
H
O
P
O
O
O
O
P –
–
3-
d-
d-
d-
Resonance
stabilization
2
Fig:- chemical basis for the large free energy
change associated with ATP hydrolysis
O
H
H
O
O
–
O
–
O
P O O
O
–
O
P
O
–
O
P Rib Adenine
O
O
–
O
O
–
O
P
O
–
O
P Rib Adenine
O
O
H O
O
–
O
P
O
–
O
P Rib Adenine
d-
H
+
1
hydrolysis with relief
of charge repulsion
3 ionization
ADP3-
ADP2-
ATP4-
+

6. ATP Provides Energy by Group Transfers, Not by Simple
Hydrolysis:

 But in actual reaction of ATP is two step process.
 In which a phosphate group is first transferred to a substrate molecule or to
an amino acid residue in an enzyme
 In the second step the phosphate containing moiety transferred in the first
step is displaced, generating Pi.
 ATP participate in enzyme catalyzed reaction to which it contribute free
energy
reactions of ATP appear to be simple hydrolysis reactions in which water displaces Pi.

7. Thank
you