Q. 18.58 - An Introduction to General, Organic, and Biological Chemistry

Question

Lignoceric acid, ${\mathrm{CH}}_3-{\left({\mathrm{CH}}_2\right)}_{22}-\mathrm{COOH}$, is a ${\mathrm{C}}_{24}$ fatty acid found in peanut oil in small amounts.

a. State the number of $\mathrm{\beta }$-oxidation cycles for the complete oxidation of lignoceric acid.

b. State the number of acetyl CoA from the complete oxidation of lignoceric acid. 

c. How many ATP are generated from the complete oxidation of lignoceric acid?

Step-by-Step Solution

Answer

(a) The eleven cycles of $\mathrm{\beta }$-oxidation are needed

(b) The twelve acetyl-CoA are produced

(c) The $162$ ATP is generated from the oxidation of lignoceric acid

Part (a) Step 1: Given information

We need to find the no. of cycles of $\mathrm{\beta }$-oxidation needed  

Part (a) Step 2: Explanation

Acetyl COA is formed when fatty acids are oxidized. Beta oxidation of fatty acids removes two carbons from the carboxylic end in stage two of fat metabolism. Each $\mathrm{\beta }$-oxidation produces acetyl-CoA and a two-carbon shorter fatty acid. $\mathrm{\beta }$-oxidation continues until acetyl-CoA is formed from the fatty acid.

To be entirely oxidized, lignoceric acid, a ${\mathrm{C}}_{24}$ monosaturated fatty acid, must go through eleven $\mathrm{\beta }$-oxidation cycles.

Part (b) Step 1: Given information

We need to find the no. of acetyl CoA produced 

Part (b) Step 2: Explanation

Acetyl COA is formed when fatty acids are oxidized. $\mathrm{\beta }$ -oxidation of fatty acids removes two carbons from the carboxylic end in stage two of fat metabolism. Each data-custom-editor="chemistry" $\mathrm{\beta }$-oxidation produces acetyl-CoA and a two-carbon shorter fatty acid. -oxidation continues until acetyl-CoA is formed from the fatty acid.

To be entirely oxidized, lignoceric acid, a data-custom-editor="chemistry" ${\mathrm{C}}_{24}$ monosaturated fatty acid, must go through eleven $\mathrm{\beta }$-oxidation cycles. As a result, twelve acetyl-CoA are produced after eleven data-custom-editor="chemistry" $\mathrm{\beta }$-oxidation cycles

Part (c) Step 1: Given information

We need to find the ATP generated from the oxidation of lignoceric acid 

Part (c) Step 2: Explanation

One NADH, one ${\mathrm{FADH}}_2$ , and one acetyl-CoA are created in each $\mathrm{\beta }$-oxidation cycle. It's worth noting that NADH and ${\mathrm{FADH}}_2$ both produce three and two ATP, respectively. Furthermore, the activation of the fatty acid necessitates the use of two ATP molecules.

Oleic acid goes through eight $\mathrm{\beta }$-oxidation cycles, yielding nine acetyl-CoA.

Therefore, $162$ ATP are generated