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Unformatted text preview: for ATP Hydrolysis. A direct measurement of the standard free-energy change associated with the hydrolysis of ATP is technically demanding because the minute
amount of ATP remaining at equilibrium is difﬁcult to measure accurately. The value of G’º can be calculated indirectly, however, from the equilibrium constants of two other enzimatic reactions having less favorable
Glucose 6-phosphate+ H2O ——> Glucose 1-phosphate ;Keq= 270
ATP + glucose ———————-> ADP + glucose 6-phosphate; Keq= 890
Using this information for equilibrium constants determined at 25 ºC, calculate the standard free energy of
hydrolysis of ATP.
G'1 = (-2.48 kJ/mol)(ln270) = -14 kJ/mol
G'2 = (-2.48 kJ/mol)(ln890) = -17 kJ/mol
G'sum = G'1 + G'2 = -31 kJ/mol 4. (15%) The G’º for Coupled Reactions. Glucose 1-phosphate is converted in to fructose 6-phosphate in two successive reactions:
a) Glucose 1-phosphate ——–> glucose 6-phosphate G1 = -7.3 kJ/mol b) Glucose 6-phosphate ——-> fructose 6-phosphate G2 = 1.7 kJ/mol 1 Calculate the equilibrium constant, K...
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- Spring '14