protein deamination

Definition

Target type: biologicalprocess

The removal of an amino group from a protein amino acid. [GOC:ai]

Deamination is a chemical reaction that removes an amine group from a molecule. In the context of proteins, deamination specifically refers to the removal of an amine group from an amino acid side chain. This process is essential for a variety of biological functions, including:

**1. Amino Acid Metabolism:**

* **Glutamate Deamination:** Deamination of glutamate, catalyzed by the enzyme glutamate dehydrogenase, is a key step in amino acid metabolism. It generates α-ketoglutarate, a crucial intermediate in the citric acid cycle.

* **Aspartate Deamination:** Deamination of aspartate, catalyzed by aspartate aminotransferase, is another important step in amino acid metabolism. It produces oxaloacetate, which is also a central molecule in the citric acid cycle.

**2. Nitrogen Excretion:**

* Deamination of amino acids produces ammonia (NH3), a toxic byproduct that needs to be excreted from the body. In mammals, ammonia is converted to urea in the liver and excreted in urine.

**3. Regulation of Enzyme Activity:**

* Deamination can affect the activity of certain enzymes by modifying their structure or modifying their substrate binding sites. For instance, deamination of lysine residues in proteins can alter their activity.

**4. Signal Transduction:**

* In some cases, deamination can act as a signal for cellular processes. For example, the deamination of glutamine residues in proteins can activate signaling pathways.

**5. DNA Replication and Repair:**

* Deamination of cytosine bases in DNA can lead to mutations. This can be a significant problem, as these mutations can affect gene expression and lead to diseases. Cells have evolved sophisticated mechanisms to repair these deaminated cytosine bases.

**The Molecular Mechanism of Deamination:**

Deamination reactions are often catalyzed by enzymes called deaminases. These enzymes typically use water as a nucleophile to attack the amine group, leading to the formation of ammonia and a carbonyl group. The carbonyl group can then be further modified, leading to the production of different products depending on the specific amino acid residue being deaminated.

**Example:**

A well-studied example of deamination is the deamination of adenosine to inosine in RNA, catalyzed by the enzyme adenosine deaminase. This reaction is essential for the regulation of gene expression and can be targeted for therapeutic purposes.

**In summary, deamination is a multifaceted process that plays crucial roles in various biological pathways. From amino acid metabolism to DNA repair, deamination is involved in maintaining cellular homeostasis and ensuring proper cellular function.**'
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Proteins (1)

Compounds (16)