oxidoreductase activity, acting on NAD(P)H, quinone or similar compound as acceptor

Definition

Target type: molecularfunction

Catalysis of an oxidation-reduction (redox) reaction in which NADH or NADPH acts as a hydrogen or electron donor and reduces a quinone or a similar acceptor molecule. [GOC:ai]

Oxidoreductase activity, acting on NAD(P)H, quinone or similar compound as acceptor, is a fundamental biochemical process involving the transfer of electrons from a reduced coenzyme, specifically NADH or NADPH, to a quinone molecule or a similar electron acceptor. This enzymatic activity is crucial for a wide range of cellular functions, including energy production, biosynthesis, and detoxification.

**Mechanism:**
These enzymes catalyze the oxidation of NADH or NADPH, which are electron carriers, while simultaneously reducing the quinone molecule. This redox reaction involves the movement of electrons from the reduced coenzyme to the quinone substrate. The specific quinone molecule can vary depending on the enzyme and its biological role.

**Biological Roles:**
* **Energy production:** In electron transport chains, such as those found in mitochondria, these enzymes are involved in generating ATP, the primary energy currency of cells.
* **Biosynthesis:** They are also involved in the synthesis of various essential molecules, including fatty acids, steroids, and pigments.
* **Detoxification:** Oxidoreductases can detoxify harmful compounds by reducing them to less toxic forms.
* **Signal transduction:** Some enzymes of this class are involved in signaling pathways, regulating cellular processes.

**Examples:**
* **NADH dehydrogenase (ubiquinone):** This enzyme is a crucial component of the electron transport chain in mitochondria. It catalyzes the transfer of electrons from NADH to ubiquinone (coenzyme Q), a key step in energy production.
* **NADPH cytochrome P450 reductase:** This enzyme plays a crucial role in detoxification pathways. It transfers electrons from NADPH to cytochrome P450 enzymes, which then oxidize and detoxify various toxins.

**Specificity and Diversity:**
There are various types of oxidoreductases with different substrate specificities and cellular locations. This diversity reflects the wide range of biological processes in which these enzymes are involved.'
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Proteins (6)

Compounds (46)