Question

Identify each of the following reactions in the β oxidation of palmitic acid, a C₁₆ fatty acid, as (1) activation, (2) first oxidation, (3) hydration, (4) second oxidation, (5) cleavage (thiolysis):

a. Palmitoyl CoA and FAD form $\alpha ,\beta$unsaturated fatty acids.

b. $\mathrm{\beta }$-ketopalmitoyal CoA forms myristoyl CoA and acetyl CoA.

c. Palmitic acid, CoA, and ATP from palmitoyal CoA .

d. $\alpha ,\beta$unsaturated palmitoyal CoA and water from $\mathrm{\beta }$-hydroxy palmitoyal CoA.

e. $\mathrm{\beta }$ -hydroxy palmitoyal CoA and NAD⁺ from $\mathrm{\beta }$-ketopalmitoyal CoA and NADH + H⁺

Short answer

a. first oxidation

b. Cleavage

c. Activation

d. Hydration followed by Second oxidation

e. Second oxidation

Step-by-step solution

Part (a) Given information

Palmitoyl CoA and FAD form $\mathrm{\alpha },\mathrm{\beta }$unsaturated fatty acids.

Part (a) Explanation

The first step is oxidation.

The dehydrogenation of fatty acyl CoA forms a trans double bond between alpha and beta carbon. In this step, an electron is transferred to FAD.

Part (b) Given information

$\mathrm{\beta }$-ketopalmitoyal CoA forms myristoyl CoA and acetyl CoA.

Part (b) Explanation

This is the fifth step which is cleavage which is known as thiolysis.

Part (c)  Explanation

Palmitic acid, CoA, and ATP from palmitoyal CoA .

It is the first step that is the activation.

Part (d)   Given information

$\mathrm{\alpha },\mathrm{\beta }$ unsaturated palmitoyal CoA and water from $\mathrm{\beta }$ -hydroxy palmitoyal CoA.

Step 2; Part (d) Explanation

This step is the hydration process followed by second oxidation.

Second oxidation:

Step 1:Part (e)   Given information

$\mathrm{\beta }$-hydroxy palmitoyal CoA and NAD⁺ from $\mathrm{\beta }$-ketopalmitoyal CoA and NADH + H⁺

Part (e) Explanation

This step is also second oxidation.