Identify each of the following reactions a to e in the β oxidation of palmitic acid, a C₁₆ fatty acid, as (18.7) (1) activation
(2) first oxidation
(3) hydration
(4) second oxidation
(5) cleavage


a. Palmitoyl CoA and FAD form α , β-unsaturated palmitoyl CoA and FADH₂

Verified step by step guidance

1. Identify the reaction type by examining the reactants and products involved.
2. Recognize that palmitoyl CoA is being converted to an α, β-unsaturated palmitoyl CoA.
3. Note that FAD is being reduced to FADH₂ in the process.
4. Understand that the formation of a double bond between the α and β carbons is characteristic of an oxidation reaction.
5. Classify this step as the 'first oxidation' in the β oxidation pathway.

Key Concepts

β-Oxidation

β-Oxidation is a metabolic process that breaks down fatty acids into acetyl-CoA units, which can then enter the citric acid cycle for energy production. This process occurs in the mitochondria and involves a series of enzymatic reactions that sequentially remove two-carbon units from the fatty acid chain, starting from the carboxyl end.

Fatty Acid Activation

Fatty acid activation is the initial step in β-oxidation, where fatty acids are converted into acyl-CoA derivatives. This reaction is catalyzed by acyl-CoA synthetase and requires ATP, which is hydrolyzed to AMP and pyrophosphate. This activation is crucial as it allows fatty acids to be transported into the mitochondria for subsequent oxidation.

Enzymatic Reactions in β-Oxidation

The β-oxidation pathway consists of four main enzymatic reactions: oxidation, hydration, another oxidation, and cleavage. Each step is catalyzed by specific enzymes, such as acyl-CoA dehydrogenase for the first oxidation, which introduces a double bond, and enoyl-CoA hydratase for hydration, which adds water across the double bond, facilitating the breakdown of fatty acids into acetyl-CoA.