isoprenoid metabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways involving isoprenoid compounds, isoprene (2-methylbuta-1,3-diene) or compounds containing or derived from linked isoprene (3-methyl-2-butenylene) residues. [ISBN:0198547684]

Isoprenoids are a diverse class of organic molecules that play vital roles in all living organisms. They are derived from the five-carbon precursor isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMAPP). The isoprenoid metabolic process encompasses the biosynthesis, modification, and degradation of isoprenoids.

**Biosynthesis:**

* **Mevalonate pathway:** This is the classical pathway for isoprenoid biosynthesis found in most eukaryotes and some bacteria. It begins with the condensation of acetyl-CoA to form mevalonic acid, which is subsequently phosphorylated and decarboxylated to produce IPP and DMAPP.
* **Methylerythritol phosphate (MEP) pathway:** This alternative pathway is found in bacteria, plastids of plants, and some algae. It utilizes pyruvate and glyceraldehyde 3-phosphate as starting materials and proceeds through a series of enzymatic steps to produce IPP and DMAPP.

**Modification:**

* **Prenylation:** IPP and DMAPP are used as building blocks for the synthesis of longer isoprenoids. They are linked together by prenyltransferases, which catalyze the formation of C10, C15, C20, and other isoprenoids.
* **Cyclization:** Many isoprenoids undergo cyclization reactions to form complex ring structures. These reactions are catalyzed by various enzymes, including cyclases and isomerases.
* **Oxidation and reduction:** Isoprenoids can be modified by oxidation, reduction, and other reactions to generate a wide array of functional groups.

**Degradation:**

* Isoprenoids can be degraded through various enzymatic pathways. The degradation products can be used as precursors for other metabolic pathways or excreted as waste products.

**Biological Functions:**

* **Steroids:** Cholesterol, a major component of cell membranes, is an important isoprenoid. Other steroids, such as hormones like estrogen and testosterone, are also derived from isoprenoids.
* **Carotenoids:** These pigments are essential for photosynthesis and act as antioxidants. Examples include beta-carotene and lycopene.
* **Terpenes:** These volatile compounds are found in plants and contribute to their scents and flavors. Examples include menthol and limonene.
* **Ubiquinone (Coenzyme Q):** An essential electron carrier in the mitochondrial electron transport chain.
* **Dolichol:** A long-chain isoprenoid involved in protein glycosylation.
* **Prenylated proteins:** These proteins are modified by the attachment of isoprenoids, which can affect their localization, function, and stability.

The isoprenoid metabolic process is highly regulated and interconnected with other metabolic pathways. It is essential for a wide range of biological functions, including cell growth, development, and response to environmental stimuli.'
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Proteins (1)

Compounds (13)