fatty acid oxidation

Definition

Target type: biologicalprocess

The removal of one or more electrons from a fatty acid, with or without the concomitant removal of a proton or protons, by reaction with an electron-accepting substance, by addition of oxygen or by removal of hydrogen. [ISBN:0198506732, MetaCyc:FAO-PWY]

Fatty acid oxidation is a complex metabolic process that occurs in the mitochondria of eukaryotic cells. It involves the breakdown of fatty acids into acetyl-CoA, which can then enter the citric acid cycle to produce energy in the form of ATP. The process can be divided into four main stages:

1. Activation and Transport:
- Fatty acids are first activated by attaching them to coenzyme A (CoA) to form fatty acyl-CoA. This reaction requires ATP.
- The activated fatty acyl-CoA is then transported into the mitochondrial matrix, where fatty acid oxidation takes place.

2. Beta-oxidation:
- Beta-oxidation is a cyclical process that involves the removal of two carbon units from the fatty acyl-CoA molecule at a time, in the form of acetyl-CoA.
- Each cycle consists of four steps:
- Oxidation: The fatty acyl-CoA is oxidized by flavin adenine dinucleotide (FAD), producing FADH2.
- Hydration: Water is added to the molecule, forming a hydroxyl group.
- Oxidation: The hydroxyl group is oxidized by nicotinamide adenine dinucleotide (NAD+), producing NADH.
- Cleavage: The molecule is cleaved by coenzyme A, producing acetyl-CoA and a shorter fatty acyl-CoA.

3. Acetyl-CoA Oxidation:
- The acetyl-CoA produced by beta-oxidation enters the citric acid cycle, also known as the Krebs cycle.
- The citric acid cycle further oxidizes acetyl-CoA, generating ATP, NADH, and FADH2.

4. Electron Transport Chain:
- The NADH and FADH2 produced during beta-oxidation and the citric acid cycle are used as electron carriers in the electron transport chain.
- The electron transport chain uses these electrons to pump protons across the inner mitochondrial membrane, creating a proton gradient.
- The energy stored in this gradient is then used to produce ATP by ATP synthase.

The energy yield from fatty acid oxidation is significant, providing a major source of ATP for the cell. The process is essential for various cellular functions, including:

- Energy production: Fatty acid oxidation is a major source of ATP for the body, especially during periods of fasting or exercise.
- Gluconeogenesis: Fatty acid oxidation can provide precursors for the synthesis of glucose during periods of fasting or starvation.
- Biosynthesis: The products of fatty acid oxidation can be used as building blocks for other molecules, such as cholesterol and steroid hormones.

Regulation:
- Fatty acid oxidation is tightly regulated by a variety of factors, including the availability of fatty acids, the energy status of the cell, and hormonal signals.
- Insulin inhibits fatty acid oxidation, while glucagon stimulates it.

Disorders:
- Disorders of fatty acid oxidation can lead to a variety of health problems, including hypoglycemia, muscle weakness, and liver disease.
- These disorders are often inherited and can be caused by defects in the enzymes involved in fatty acid oxidation.

In summary, fatty acid oxidation is a vital process that plays a key role in energy metabolism. It is essential for the efficient production of ATP and provides precursors for various biosynthetic pathways.'
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Proteins (9)

Compounds (441)