Question

Question: Predict whether creatine kinase will operate in the direction of ATP synthesis or phosphocreatine synthesis at ${25}^{°}C$ when [ATP]$=4mM$ , [ADP]$=0.15mM$ , [phosphocreatine]$=2.5mM$ , and [creatine]$=1mM$ .

Short answer

Answer

The process will progress towards ATP production.

Step-by-step solution

Step-by-step-solutionStep 1: ATP synthesis

The cellular respiration process is where ATP is largely synthesized.The oxidation of respiratory substrates such carbohydrates, lipids, and proteins produces ATP.

Work done to perform this action

The direction of the reaction is determined by free energy change. If is less than , reaction will proceed as written, if it is equal to there will be no net change and if it is larger than , reaction will proceed in opposite direction.

To calculate $∆G$ we use following expression:

data-custom-editor="chemistry" $∆\mathrm{G}=∆{\mathrm{G}}^{°}+\mathrm{RTln}\frac{\left[\mathrm{C}\right]\left[\mathrm{D}\right]}{\left[\mathrm{A}\right]\left[\mathrm{B}\right]}$

Temperature is in kelvin, data-custom-editor="chemistry" ${27}^{°}C=298K$ , concentrations can be in the value mM since it cancels out.

$$\begin{gathered} ∆\mathrm{G}=12.6{\mathrm{kJmol}}^{-1}+8.314{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}\times 298\mathrm{K}\times \ln \frac{2.5\times 0.5}{1\times 4} \\ =6.7kJmo{l}^{-1} \end{gathered}$$

Resulting free energy change is larger than 0, which means that reaction will proceed in opposite direction, towards the ATP synthesis.

Hence, the reaction will proceed towards the ATP synthesis.