oxidoreductase activity

Definition

Target type: molecularfunction

Catalysis of an oxidation-reduction (redox) reaction, a reversible chemical reaction in which the oxidation state of an atom or atoms within a molecule is altered. One substrate acts as a hydrogen or electron donor and becomes oxidized, while the other acts as hydrogen or electron acceptor and becomes reduced. [GOC:go_curators]

Oxidoreductases are a broad class of enzymes that catalyze oxidation-reduction reactions, which involve the transfer of electrons between molecules. These reactions are essential for many biological processes, including energy production, biosynthesis, detoxification, and signal transduction. The general reaction catalyzed by oxidoreductases can be represented as:

**Reduced substrate + Oxidized cofactor u003c=u003e Oxidized substrate + Reduced cofactor**

Where:

* **Reduced substrate** is a molecule that donates electrons.
* **Oxidized cofactor** is a molecule that accepts electrons.
* **Oxidized substrate** is a molecule that has lost electrons.
* **Reduced cofactor** is a molecule that has gained electrons.

Oxidoreductases utilize a wide variety of cofactors, including nicotinamide adenine dinucleotide (NAD+), nicotinamide adenine dinucleotide phosphate (NADP+), flavin adenine dinucleotide (FAD), and cytochrome c. These cofactors act as electron carriers, accepting electrons from the reduced substrate and transferring them to the oxidized substrate.

**Types of Oxidoreductases:**

Oxidoreductases are classified based on the type of reaction they catalyze and the substrate they act upon. Some common types include:

* **Dehydrogenases:** These enzymes remove hydrogen atoms from their substrates, transferring electrons to an electron acceptor like NAD+ or NADP+.
* **Oxygenases:** These enzymes incorporate oxygen atoms into their substrates.
* **Reductases:** These enzymes add electrons to their substrates, often using NADH or NADPH as electron donors.
* **Peroxidases:** These enzymes use hydrogen peroxide as an electron acceptor.
* **Catalases:** These enzymes catalyze the decomposition of hydrogen peroxide into water and oxygen.

**Examples of Oxidoreductase Activity:**

* **Glycolysis:** The enzyme glyceraldehyde-3-phosphate dehydrogenase catalyzes the oxidation of glyceraldehyde-3-phosphate, producing NADH.
* **Citric acid cycle:** The enzyme succinate dehydrogenase catalyzes the oxidation of succinate to fumarate, reducing FAD to FADH2.
* **Electron transport chain:** Cytochrome c oxidase, a terminal oxidase in the electron transport chain, catalyzes the transfer of electrons from cytochrome c to oxygen, producing water.
* **Detoxification:** The enzyme cytochrome P450 monooxygenases catalyze the oxidation of various toxins and drugs, rendering them less harmful.
* **Signal transduction:** The enzyme NADPH oxidase produces reactive oxygen species (ROS) that act as signaling molecules in various cellular processes.

Oxidoreductases are essential for life and play critical roles in diverse biological processes. Their ability to catalyze the transfer of electrons allows them to drive energy production, biosynthetic pathways, and other cellular functions.'
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Proteins (29)

Compounds (1,894)