aspartate biosynthetic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of aspartate, the anion derived from aspartic acid, 2-aminobutanedioic acid. [GOC:go_curators, ISBN:0198506732]

Aspartate biosynthesis is a fundamental metabolic process that generates aspartate, a non-essential amino acid with diverse roles in cellular metabolism. This process is essential for the production of proteins, nucleic acids, and other critical biomolecules. Aspartate biosynthesis occurs in a series of enzymatic reactions, with the primary pathway in most organisms being the **transamination of oxaloacetate**.

**The primary pathway involves the following steps:**

1. **Oxaloacetate**, a four-carbon dicarboxylic acid, is the precursor for aspartate synthesis. Oxaloacetate is a key intermediate in the citric acid cycle (Krebs cycle), and it can be produced from various sources, including glucose metabolism and amino acid degradation.

2. **Transamination** is the key enzymatic reaction in aspartate biosynthesis. In this process, the amino group from an amino acid donor, typically glutamate, is transferred to oxaloacetate, resulting in the formation of aspartate and alpha-ketoglutarate. This reaction is catalyzed by **aspartate aminotransferase (AST)**, a ubiquitous enzyme found in all living organisms.

**Additional pathways:**

While the transamination of oxaloacetate is the primary route for aspartate biosynthesis, alternative pathways can operate in specific organisms or under certain conditions:

- **Aspartate synthetase (AS)** catalyzes the direct synthesis of aspartate from ammonia and fumarate, a four-carbon dicarboxylic acid produced in the citric acid cycle. This pathway is particularly important in bacteria and plants.

- **Aspartate decarboxylase** converts aspartate into beta-alanine, a precursor for pantothenate (vitamin B5) biosynthesis.

**Regulation:**

The aspartate biosynthetic process is tightly regulated to ensure adequate supply of aspartate while minimizing the accumulation of intermediates. Regulation occurs at various levels, including:

- **Enzyme activity**: The activity of AST and AS is regulated by various factors, including substrate availability, product accumulation, and cellular energy status.

- **Gene expression**: The expression of genes encoding aspartate biosynthetic enzymes is regulated in response to changes in cellular needs and environmental conditions.

**Biological significance:**

Aspartate plays a crucial role in a wide range of biological processes, including:

- **Protein synthesis**: Aspartate is a building block for proteins, contributing to their structure and function.

- **Nucleic acid synthesis**: Aspartate is a precursor for the synthesis of pyrimidine nucleotides, which are essential components of DNA and RNA.

- **Metabolism**: Aspartate serves as a carbon source for various metabolic pathways, including the urea cycle, the citric acid cycle, and the biosynthesis of amino acids, such as asparagine, lysine, and methionine.

- **Neurotransmitter synthesis**: Aspartate is a neurotransmitter in the central nervous system, involved in signal transmission between neurons.

**In summary, aspartate biosynthesis is a critical metabolic process that generates a versatile amino acid with diverse biological roles. The transamination of oxaloacetate is the primary pathway for aspartate production, while alternative pathways operate in specific organisms. The process is tightly regulated to ensure adequate aspartate supply and maintain metabolic balance.**'
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Proteins (1)

Compounds (6)