Chapter 23, Problem 23.33P

Interpretation Introduction

(a)

Interpretation:

The equation for the coupled reaction of 1,3-bisphosphoglycerate with ADP to form 3-phosphoglycerate and ATP should be written.

Concept Introduction:

Phosphorylation of 1,3-bisphosphoglycerate is energetically unfavorable reaction. By coupling with the ATP hydrolysis, this reaction can be converted to a favorable state.

Answer to Problem 23.33P

  $\text{1,3-bisphosphoglycerate}+\text{ADP }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}+\text{ATP}$

Explanation of Solution

The conversion of 1,3-bisphosphatoglycerate to 3-phosphoglycerate and hydrogen phosphate can be represented as follows:

  ${\text{1,3-bisphosphoglycerate + H}}_2\text{O }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}{\text{ + HPO}}_4{}^{2-}$.......(1)

Similarly, the conversion of ATP to ADP can be represented as follows:

  ${\text{ATP + H}}_2\text{O }\to {\text{ADP + HPO}}_4{}^{2-}$.......(2)

To cancel the common species, reaction (1) should be added to the reverse of reaction (2).

The coupled reaction can be represented as follows:

  $\begin{array}{l}{\text{1,3-bisphosphoglycerate + H}}_2\text{O }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}{\text{ + HPO}}_4{}^{2-}\\ {\text{ ADP + HPO}}_4{}^{2-}\to {\text{ATP + H}}_2\text{O}\\ \overline{\underset{\_}{\text{1,3-bisphosphoglycerate}+\text{ADP }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}+\text{ATP }}}\end{array}$

  $$

Interpretation Introduction

(b)

Interpretation:

The energy change for this coupled reaction should be calculated.

Concept Introduction:

Phosphorylation of 1,3-bisphosphoglycerate is energetically unfavorable reaction. by coupling with the ATP hydrolysis, this reaction can be converted to a favorable state.

In the hydrolysis of ATP breaks one phosphate group, forming ADP and hydrogen phosphate, This reaction releases 7.3 kcal/mol of energy.

When the energy of a reaction is a positive value, that reaction is an endothermic reaction and it requires the energy of surrounding to complete the reaction.

When the energy of a reaction is a negative value, that reaction is exothermic, and it releases energy by acting as an energetically favorable reaction.

Answer to Problem 23.33P

- 4.5kcal/mol

Explanation of Solution

The conversion of 1,3-bisphosphatoglycerate to 3-phosphoglycerate and hydrogen phosphate can be represented as follows:

  ${\text{1,3-bisphosphoglycerate + H}}_2\text{O }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}{\text{ + HPO}}_4{}^{2-}$.......(1)

The energy for the above reaction is $\text{ - 11}\text{.8 kacal/mol}$.

Similarly, the conversion of ATP to ADP can be represented as follows:

${\text{ATP + H}}_2\text{O }\to {\text{ADP + HPO}}_4{}^{2-}$.........(2)

The energy for the above reaction is $\text{ -7}\text{.3 kcal/mol}$.

To cancel the common species, reaction (1) should be added to the reverse of reaction (2).

The coupled reaction can be represented as follows:

  $\begin{array}{l}{\text{1,3-bisphosphoglycerate + H}}_2\text{O }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}{\text{ + HPO}}_4{}^{2-}\text{ - 11}\text{.8 kcal/mol}\\ {\text{ ADP + HPO}}_4{}^{2-}\to {\text{ATP + H}}_2\text{O +7}\text{.3 kcal/mol }\\ \overline{\underset{\_}{\text{1,3-bisphosphoglycerate}+\text{ADP }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}+\text{ATP }-4.\text{5 kcal/mol }}}\end{array}$

Thus, the energy change for the reaction is $-4.\text{5 kcal/mol }$.

Interpretation Introduction

(c)

Interpretation:

Whether this reaction is used to synthesize ATP from ADP should be explained.

Concept Introduction:

The reaction releases 7.3 kcal/mol of energy.

When the energy of a reaction is a positive value, that reaction is an endothermic reaction and it requires the energy of surrounding to complete the reaction.

When the energy of a reaction is a negative value, that reaction is exothermic, and it releases energy by acting as an energetically favorable reaction.

Answer to Problem 23.33P

This can be used to produce ATP.

Explanation of Solution

  $\begin{array}{l}{\text{ATP + H}}_2\text{O }\to {\text{ADP + HPO}}_4{}^{2-}\text{ -7}\text{.3 kcal/mol}\\ \\ {\text{1,3-bisphosphoglycerate + H}}_2\text{O }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}{\text{ + HPO}}_4{}^{2-}\text{ - 11}\text{.8 kacal/mol}\\ \\ \text{1,3-bisphosphoglycerate}+\text{ADP }\to \begin{array}{l}\text{3-phosphoglycerate}\hfill \end{array}+\text{ATP}\\ \\ \end{array}$

Energy = -11.8 kcal/mol + 7.3 kcal/mol = - 4.5kcal/mol

When the energy of a reaction is a negative value, that reaction is exothermic, and it releases energy by acting as an energetically favorable reaction. Therefore, this can be used to produce ATP.