Chapter 24, Problem 24.71UTC

Interpretation Introduction

(a)

To determine: The line–angle structural formula for the activated form of lauric acid.

Answer to Problem 24.71UTC

Solution: The line–angle structural formula for the activated form of lauric acid is:

Explanation of Solution

Lauric acid is a saturated $C_{12}$ fatty acid. It can be activated by Coenzyme A catalysed by Acyl CoA synthetase.

Thus, the activated form of Lauric acid is:

Interpretation Introduction

(b)

To determine: The α- and β-carbon atoms in the acyl molecule of lauric acid.

Answer to Problem 24.71UTC

Solution: The α- and β-carbon atoms in the acyl molecule of lauric acid is:

Explanation of Solution

The carbon attached to the carbonyl carbon is considered as α-carbon and the carbon next to α-carbon is called as β-carbon.

Thus the α- and β-carbon atoms in the acyl molecule of lauric acid can be represented as

Interpretation Introduction

(c)

To determine: The number of cycles of β- oxidation needed for complete β-oxidation of lauric acid.

Answer to Problem 24.71UTC

Solution: The number of cycles of β- oxidation needed for complete β-oxidation of lauric acid is five ($5$).

Explanation of Solution

The acetyl group of the acetyl CoA is formed by two carbons and in the last round two acetyl CoA is produced. Accordingly the number of cycles of β-oxidation has been calculated.

No. of cycles of β-oxidation are needed for the complete oxidation of fatty acid = (n/2)-1 where n = No. of carbon atoms present in fatty acid.

As here no. of carbon atoms in the given fatty acid = 12

So, by putting n = 12

We get, No. of cycles of β-oxidation are needed for the complete oxidation of fatty acid = (12/2) -1 = 5

Thus, five ($5$) cycles of β-oxidation are needed for the complete oxidation of lauric acid.

Interpretation Introduction

(d)

To determine: The number of acetyl CoA units produced from the complete β-oxidation of lauric acid.

Answer to Problem 24.71UTC

Solution: The number of acetyl CoA units produced from the complete β-oxidation of lauric acid is six ($6$).

Explanation of Solution

The acetyl group of the acetyl CoA is formed by two carbons. Accordingly the number of acetyl CoA produced has been calculated.

No. of acetyl CoA are produced from the complete oxidation of fatty acid = (n/2)

where n = No. of carbon atoms present in fatty acid.

As here no. of carbon atoms in the given fatty acid = 12

So, by putting n=12

We get, No. of acetyl CoA are produced from the complete oxidation of fatty acid = (12/2) = 6

Thus, from complete oxidation of lauric acid six(6) acetyl CoA are produced.

Interpretation Introduction

(e)

To determine: The total ATP yield from the complete β-oxidation of lauric acid.

Answer to Problem 24.71UTC

Solution: The total ATP yield from the complete β-oxidation of lauric acid is $78$.

Explanation of Solution

From the complete β-oxidation of lauric acid, total six(6) acetyl CoA, 5 NADH and 6 FADH₂ has been produced. Each Acetyl CoA yields 10 ATP, each NADH yields 2.5 ATP and each FADH₂ yields 1.5 ATP. Accordingly, ATP yield has been calculated.

Lauric Acid is a C₁₂ fatty acid. And for the activation of lauric acid 2 ATP is required.

Activation		-2 ATP
Acetyl CoA	6x10ATP/Acetyl CoA	60ATP
NADH.H	5x2.5 ATP/NADH	12.5 ATP
FADH2	5x1.5 ATP/ FADH2	7.5 ATP
Total		78 ATP

Thus, 78 ATP yields from the complete oxidation of lauric acid.

Conclusion

Therefore, the line-angle structural formula for the activated form, α- and β-carbon atoms in the acyl molecule, number of cycles of β- oxidation, number of acetyl CoA units produced and the total ATP yield from the complete β- oxidation of lauric acid has been discussed.