reactive oxygen species biosynthetic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of reactive oxygen species, any molecules or ions formed by the incomplete one-electron reduction of oxygen. [GO_REF:0000068, GOC:bf, GOC:PARL, GOC:TermGenie, PMID:24252804]

Reactive oxygen species (ROS) biosynthesis is a fundamental process in cellular metabolism, generating a diverse array of oxygen-derived molecules with varying degrees of reactivity. These species, including superoxide anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (OH-), are inherently unstable and highly reactive, capable of engaging in a multitude of chemical reactions. ROS production primarily occurs within cellular organelles like mitochondria, peroxisomes, and the endoplasmic reticulum, as well as in specialized enzymatic pathways. While often associated with oxidative stress and cellular damage, ROS serve crucial roles in various biological processes, including signal transduction, redox homeostasis, immune response, and apoptosis.

The primary sources of ROS generation can be categorized into two major pathways:

1. **Enzymatic pathways:**
* **NADPH oxidases (NOX enzymes):** This family of transmembrane enzymes catalyzes the one-electron reduction of molecular oxygen to superoxide anion, a key step in the production of other ROS. NOX enzymes are involved in diverse physiological functions, including immune response, vascular tone regulation, and wound healing.
* **Mitochondrial electron transport chain:** During oxidative phosphorylation, a small proportion of electrons leak from the electron transport chain and react with molecular oxygen, generating superoxide. This process is a major source of ROS in cells and can be influenced by factors such as mitochondrial dysfunction and metabolic stress.
* **Xanthine oxidase:** This enzyme converts hypoxanthine and xanthine to uric acid, producing superoxide as a byproduct. Its activity is enhanced under conditions of hypoxia and inflammation.
* **Cyclooxygenase (COX) and lipoxygenase (LOX):** These enzymes are involved in the synthesis of prostaglandins and leukotrienes, respectively, and produce ROS as secondary products.
* **Peroxisomes:** These organelles contain enzymes like catalase and urate oxidase, which produce H2O2 as a byproduct of their catalytic activity.

2. **Non-enzymatic pathways:**
* **Metal-catalyzed reactions:** Transition metals like iron and copper can catalyze the formation of ROS through the Fenton reaction, where H2O2 is converted to the highly reactive hydroxyl radical.
* **Radiation exposure:** Ionizing radiation can directly interact with water molecules, generating hydroxyl radicals and other ROS.
* **Inflammation:** During inflammation, activated neutrophils and macrophages release ROS, contributing to the inflammatory cascade.

The delicate balance between ROS production and detoxification is essential for maintaining cellular function and viability. ROS serve as signaling molecules, regulating gene expression, cell proliferation, and apoptosis. However, excessive ROS production can lead to oxidative stress, a condition characterized by an imbalance between ROS generation and the cellular antioxidant defense system. Oxidative stress can damage cellular components, including DNA, proteins, and lipids, ultimately contributing to various diseases and aging.

The complexity of ROS biology underscores its intricate role in maintaining cellular homeostasis. Further research is needed to fully understand the diverse functions of ROS in health and disease, paving the way for the development of novel therapeutic strategies.'
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Proteins (3)

Compounds (27)