fatty acid elongation

Definition

Target type: biologicalprocess

The elongation of a fatty acid chain by the sequential addition of two-carbon units. [ISBN:0716720094]

Fatty acid elongation is a crucial metabolic process that extends the carbon chain length of fatty acids. It occurs in the endoplasmic reticulum (ER) of eukaryotic cells and is catalyzed by a series of enzymes known as fatty acid elongases. The process involves the sequential addition of two-carbon units (acetyl-CoA) to the carboxyl end of a pre-existing fatty acyl chain.

The first step involves the activation of the fatty acid substrate by attaching it to coenzyme A (CoA) to form acyl-CoA. Next, the acyl-CoA is transferred to the elongase complex, where it undergoes a series of reactions.

The elongase complex consists of four key enzymes:

* **Acyl-CoA dehydrogenase:** This enzyme oxidizes the fatty acyl-CoA, creating a double bond.
* **Enoyl-CoA hydratase:** This enzyme adds water across the double bond, forming a hydroxyl group.
* **3-hydroxyacyl-CoA dehydrogenase:** This enzyme oxidizes the hydroxyl group to a ketone.
* **Thiolase:** This enzyme cleaves the elongated fatty acyl-CoA from the elongase complex.

The elongated fatty acyl-CoA is then available for further metabolism or incorporation into lipids.

Fatty acid elongation is essential for the synthesis of various important lipids, including:

* **Sphingolipids:** These lipids are critical components of cell membranes and play roles in cell signaling and recognition.
* **Cerebrosides:** These lipids are abundant in the brain and other nervous tissues and contribute to myelin sheath formation.
* **Glycosphingolipids:** These lipids are involved in cell adhesion and recognition.

In addition to its role in lipid synthesis, fatty acid elongation also contributes to:

* **Regulation of membrane fluidity:** The length of fatty acid chains influences membrane fluidity. Elongation increases the length of fatty acid chains, reducing membrane fluidity.
* **Adaptation to cold temperatures:** In cold-blooded animals, fatty acid elongation helps to maintain membrane fluidity at low temperatures.

Fatty acid elongation is a tightly regulated process, with various factors influencing its activity, including:

* **Substrate availability:** The availability of fatty acids and acetyl-CoA is crucial for elongation.
* **Hormonal regulation:** Hormones like insulin and glucagon can modulate elongase activity.
* **Cellular energy status:** The cell's energy status can also influence elongase activity.

Disruptions in fatty acid elongation can lead to various diseases, including:

* **Neurological disorders:** Defects in fatty acid elongation can affect brain development and function.
* **Metabolic disorders:** Abnormal elongation can contribute to metabolic disorders like obesity and diabetes.

Overall, fatty acid elongation is a vital metabolic process with profound implications for cell function and human health.'
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Proteins (2)

Compounds (12)