proline catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of proline (pyrrolidine-2-carboxylic acid), a chiral, cyclic, nonessential alpha-amino acid found in peptide linkage in proteins. [GOC:jl, ISBN:0198506732]

Proline catabolism is a critical metabolic pathway that breaks down the amino acid proline into energy and other metabolites. It plays a crucial role in various cellular processes, including amino acid biosynthesis, energy production, and detoxification. Here's a detailed breakdown of the process:

1. **Proline Oxidation:** The process begins with the oxidation of proline to Δ¹-pyrroline-5-carboxylate (P5C) by proline oxidase. This enzyme requires molecular oxygen and produces hydrogen peroxide as a byproduct.

2. **P5C Dehydrogenase Activity:** P5C is then converted to glutamate by P5C dehydrogenase. This enzyme utilizes NAD+ as a cofactor and is highly specific for P5C.

3. **Glutamate Metabolism:** Glutamate, the product of P5C dehydrogenase, can enter various metabolic pathways. It can be used in the synthesis of other amino acids, participate in the urea cycle for nitrogen detoxification, or be further metabolized to α-ketoglutarate in the citric acid cycle for energy production.

4. **Regulation of Proline Catabolism:** The activity of proline oxidase and P5C dehydrogenase is tightly regulated by cellular conditions, such as nutrient availability and oxidative stress. This ensures that proline catabolism is balanced with other metabolic processes.

5. **Biological Significance:** Proline catabolism is essential for:

- **Energy production:** Proline breakdown generates energy through the citric acid cycle and oxidative phosphorylation.

- **Amino acid synthesis:** Glutamate, a product of proline catabolism, is a precursor for the synthesis of other amino acids, such as glutamine and arginine.

- **Nitrogen detoxification:** Proline catabolism contributes to the urea cycle, which eliminates excess nitrogen from the body.

- **Cellular protection:** Proline catabolism can protect cells from oxidative stress by providing reducing equivalents (NADH) and detoxifying reactive oxygen species.

In summary, proline catabolism is a complex metabolic pathway that plays a crucial role in energy production, amino acid synthesis, nitrogen detoxification, and cellular protection. It is a tightly regulated process that is essential for maintaining cellular homeostasis.'
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Proteins (1)

Compounds (33)