cysteine metabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways involving cysteine, 2-amino-3-mercaptopropanoic acid. [GOC:go_curators]

Cysteine metabolism is a fundamental biological process essential for various cellular functions. It involves a series of enzymatic reactions that regulate the synthesis, breakdown, and utilization of cysteine, a sulfur-containing amino acid.

Cysteine is a crucial component of proteins, acting as a building block for their structure and function. It is also involved in redox reactions, contributing to the maintenance of cellular redox homeostasis. Additionally, cysteine serves as a precursor for the biosynthesis of glutathione, a vital antioxidant.

**Synthesis:**

Cysteine can be synthesized de novo in the body from methionine via the transsulfuration pathway. This pathway involves several enzymes, including cystathionine β-synthase and cystathionine γ-lyase.

**Breakdown:**

The degradation of cysteine begins with its conversion to pyruvate and sulfate. This process is catalyzed by cysteine dioxygenase, which initiates the formation of cysteine sulfinate. Subsequent reactions lead to the production of sulfate and pyruvate.

**Utilization:**

Cysteine is utilized in various metabolic processes, including:

* **Protein synthesis:** As a building block for proteins, cysteine contributes to their structure and function.
* **Redox reactions:** Cysteine's sulfhydryl group participates in redox reactions, essential for maintaining cellular redox balance.
* **Glutathione synthesis:** Cysteine serves as a precursor for the synthesis of glutathione, a critical antioxidant molecule.
* **Other metabolic pathways:** Cysteine is involved in various metabolic pathways, including the biosynthesis of taurine, coenzyme A, and other sulfur-containing compounds.

**Regulation:**

Cysteine metabolism is tightly regulated by factors such as:

* **Nutritional intake:** Dietary cysteine intake influences the levels of cysteine in the body.
* **Hormonal signals:** Hormones like insulin and growth hormone can regulate cysteine metabolism.
* **Cellular demand:** Cellular demand for cysteine influences its synthesis and degradation.

**Disorders:**

Dysregulation of cysteine metabolism can lead to various disorders, including:

* **Cystinuria:** A genetic disorder characterized by the accumulation of cystine in the kidneys, leading to kidney stones.
* **Homocystinuria:** A metabolic disorder resulting from a deficiency in cystathionine β-synthase, leading to high levels of homocysteine in the blood.
* **Other disorders:** Cysteine metabolism is also linked to other disorders, such as neurodegenerative diseases, cardiovascular diseases, and cancer.

In summary, cysteine metabolism is a complex and essential process involved in various cellular functions. Understanding its regulation and potential dysregulation is crucial for maintaining health and preventing related disorders.'
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Proteins (1)

Compounds (15)