Citrate synthase catalyzes an aldo - type condensation. the kinetic mechanism is
ID: 35239 • Letter: C
Question
Citrate synthase catalyzes an aldo - type condensation. the kinetic mechanism is a random-sequential one where either substrate can bind first.
The free energy change for the hydrolusis of acetyl coA is G'=-43kj/mol. Howerver the G' valur for the hydrolysis of the citryl coA intermediate in the CS reaction is significantly different from the value.
Estimate this value by assuming it is the same value as that for hydrolysis of succinyl-coA ( this calue can be calculated from the known value of G'- +1.7 kJ/mol) for the succinate thiokinase reaction)
Explanation / Answer
Based on the given data, the balance reaction is:
Succinyl-CoA---> succinate
GDP+Pi ----> GTP
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Succinyl-CoA --succinyl-CoA synthetase + GDP/Pi---> Succinate + GTP
Where, the Go = +1.7 kJ/mol
The formula for calculation is:
Go’ = -nF Eo'
The Eo' of the reaction is: +3 mv
Then
= - 2(13.06) (3)
= 7.836
Thus, the DeltaG0'= 7.8 kJ/mol)