Chapter 16, Problem 1P

Interpretation Introduction

Interpretation:

Calculate the ATP yield from oxidation of palmitic acid, taking into account the energy needed to activate the fatty acid and transport it into mitochondria. Do the same for stearic acid, linoleic acid, and oleic acid.

Introduction: Fatty acid oxidation involves conversion of fatty acid into ATP, carbon dioxide and water. Three stages are involved in its oxidation:

• STAGE 1: ß-oxidation (Conversion of fatty acid into acetyl CoA
• STAGE 2: Conversion of Acetyl CoA into NADH ₂and FADH ₂
• STAGE 3: All the electrons produced in ß-oxidation and Stage 2 are used to produce ATP through electron transport chain.

  

ATP yield from oxidation of fatty acids are:

• Palmitic acid − 106 ATP
• Stearic acid − 120 ATP
• Linoleic acid − 116 ATP
• Oleic acid − 118.5 ATP ˜ 119ATP

Explanation of Solution

Activation of a fatty acid to CoA form consumes two molecules of ATP and 2ATP gets minus from the total amount of ATP synthesized in fatty acid oxidation to get the net ATP yield.

  $\text{Palmitic acid + 2ATP + CoA }\to \text{PalmitoylCoA + 2ADP + 2Pi}$

Similarly, Stearic acid, Linoleic acid and Oleic acid are activated, and Coenzyme A group is added.

1. Oxidation of Palmitic acid

  $\mathrm{PalmitoylCoA}+7CoA+7FAD+NA{D}^{+}+7H_{2}O \to 8AcetylCoA+7FAD{H}_2+7NAD{H}_2+7H^{+}\left(1\right)$

  $8AcetylCoA+16O_2+80Pi+80ADP \to 8CoA+80ATP+16C{O}_2+16H_{2}O\left(2\right)$

Adding equation (1) and (2)

  $\mathrm{PalmitoylCoA}CoA+23O_2+108Pi+108ADP \to CoA+108ATP+16C{O}_2+23H_{2}O$

108P is synthesized, and the net yield ATP is 106 ATP

2. Oxidation of Stearic acid

  $\mathrm{Stearic}acid+26O_2+120Pi+120ADP \to CoA+120ATP+18C{O}_2+26H_{2}O$

Net ATP yield is 120ATP

3. Oxidation of Linoleic acid

  $\mathrm{Linoleic}acid+26O_2+116Pi+116ADP \to CoA+116ATP+18C{O}_2+26H_{2}O$

Net ATP yield is 116ATP

4. Oxidation of Oleic acid

  ${\text{Oleic acid + 26O}}_{\text{2}}\text{+ 119 Pi + 119ADP}\to {\text{CoA + 119 ATP + 18CO}}_{\text{2}}{\text{+ 26H}}_{\text{2}}\text{O}$

The net ATP yield is 119ATP