acetyl-CoA biosynthetic process from pyruvate

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of acetyl-CoA from pyruvate. [GOC:dph, GOC:go_curators, GOC:tb]

The acetyl-CoA biosynthetic process from pyruvate is a fundamental metabolic pathway that converts pyruvate, a three-carbon molecule produced during glycolysis, into acetyl-CoA, a two-carbon molecule that serves as a central hub in cellular metabolism. This process occurs in the mitochondria of eukaryotic cells and is catalyzed by a multi-enzyme complex called the pyruvate dehydrogenase complex (PDC).

The PDC consists of three main enzymes: pyruvate dehydrogenase (E1), dihydrolipoyl transacetylase (E2), and dihydrolipoyl dehydrogenase (E3). Each enzyme plays a specific role in the conversion of pyruvate to acetyl-CoA.

1. **Decarboxylation of Pyruvate:** Pyruvate dehydrogenase (E1) catalyzes the decarboxylation of pyruvate, removing a carbon dioxide molecule and forming a hydroxyethyl group. The hydroxyethyl group is then transferred to a lipoamide cofactor attached to E2.

2. **Oxidation and Acetylation:** Dihydrolipoyl transacetylase (E2) oxidizes the hydroxyethyl group, producing an acetyl group. This acetyl group is then transferred to Coenzyme A (CoA) to form acetyl-CoA.

3. **Regeneration of Lipoamide:** Dihydrolipoyl dehydrogenase (E3) regenerates the oxidized form of lipoamide by transferring electrons to NAD+, producing NADH.

The overall reaction can be summarized as follows:

Pyruvate + CoA + NAD+ → Acetyl-CoA + CO2 + NADH + H+

Acetyl-CoA is a crucial molecule in many metabolic pathways, including:

* **Citric Acid Cycle:** Acetyl-CoA enters the citric acid cycle, providing the carbon atoms for energy production through oxidative phosphorylation.
* **Fatty Acid Synthesis:** Acetyl-CoA is used as a building block for the synthesis of fatty acids, which are important for energy storage and membrane structure.
* **Steroid Synthesis:** Acetyl-CoA is a precursor for the synthesis of cholesterol and other steroid hormones.

The acetyl-CoA biosynthetic process from pyruvate is tightly regulated to meet the cell's energy needs and maintain metabolic homeostasis. Several factors can influence the activity of the PDC, including the availability of substrates, the energy status of the cell, and hormonal signals.'
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Proteins (3)

Compounds (2)