negative regulation of plasma lipoprotein oxidation

Definition

Target type: biologicalprocess

Any process that stops, prevents, or reduces the frequency, rate or extent of lipoprotein particle oxidation, occurring in the blood plasma. [GOC:BHF, GOC:mah]

Negative regulation of plasma lipoprotein oxidation is a complex process that involves a coordinated interplay of various enzymatic and non-enzymatic mechanisms aimed at preventing the harmful oxidation of lipoproteins, particularly low-density lipoproteins (LDL), in the bloodstream. Oxidation of LDL is a critical step in the development of atherosclerosis, a disease characterized by plaque buildup in the arteries. Here's a detailed description of the biological process:

**1. Antioxidant Enzymes:**

- **Paraoxonase 1 (PON1):** This enzyme hydrolyzes oxidized phospholipids in LDL, effectively reducing their oxidation level and preventing the formation of pro-inflammatory molecules.
- **Glutathione peroxidase (GPx):** GPx reduces lipid hydroperoxides, the primary products of lipid oxidation, to their corresponding alcohols, effectively neutralizing oxidative damage.
- **Superoxide dismutase (SOD):** SOD catalyzes the dismutation of superoxide radicals, highly reactive oxygen species that can initiate lipid oxidation, into hydrogen peroxide, a less damaging species.
- **Catalase:** This enzyme degrades hydrogen peroxide, further reducing the oxidative stress in the bloodstream.

**2. Non-Enzymatic Antioxidants:**

- **Vitamin E (α-tocopherol):** This lipid-soluble antioxidant scavenges free radicals in LDL, directly preventing lipid oxidation.
- **Vitamin C (ascorbic acid):** This water-soluble antioxidant regenerates vitamin E and protects against oxidative damage by reducing reactive oxygen species.
- **Glutathione:** This tripeptide acts as a reducing agent, neutralizing free radicals and regenerating other antioxidants, such as vitamin C.
- **Carotenoids:** These pigments found in fruits and vegetables act as antioxidants, quenching singlet oxygen and other free radicals.

**3. Lipoprotein Metabolism:**

- **High-density lipoprotein (HDL):** HDL acts as a scavenger of oxidized LDL, removing it from circulation and transporting it to the liver for degradation.
- **Apolipoprotein A-I (apoA-I):** This protein is the major component of HDL and plays a crucial role in the reverse cholesterol transport pathway, removing cholesterol from peripheral tissues and delivering it to the liver.

**4. Other Regulatory Mechanisms:**

- **Inflammation:** Pro-inflammatory cytokines, such as TNF-α, can stimulate LDL oxidation and contribute to the development of atherosclerosis.
- **Lifestyle Factors:** Smoking, a high-fat diet, and a sedentary lifestyle all contribute to oxidative stress and increase the risk of LDL oxidation.

**5. Role of Oxidized LDL:**

- Oxidized LDL is highly pro-inflammatory and can trigger the adhesion of monocytes to the endothelium, leading to their differentiation into macrophages.
- These macrophages engulf oxidized LDL, becoming foam cells, a hallmark of atherosclerotic plaques.
- Oxidized LDL also contributes to the formation of reactive oxygen species, further perpetuating the oxidative damage.

In summary, negative regulation of plasma lipoprotein oxidation involves a complex network of antioxidants, enzymes, lipoprotein metabolism pathways, and other regulatory mechanisms. This intricate process is crucial for preventing the development of atherosclerosis and maintaining cardiovascular health.'
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Proteins (1)

Compounds (20)