Amine oxidase (copper-containing)

Amine_oxidase_(copper-containing)

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  Amine_oxidase_(copper-containing)

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  Amine_oxidase_(copper-containing)

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  Amine_oxidase_(copper-containing)

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  Amine_oxidase_(copper-containing)

Amine Oxidase (Copper-Containing)

Amine oxidase (copper-containing) is a class of enzymes that catalyze the oxidative deamination of primary amines to aldehydes, with the concomitant reduction of oxygen to hydrogen peroxide. These enzymes are characterized by the presence of copper ions in their active sites, which play a crucial role in the catalytic mechanism.

Structure

Amine oxidase (copper-containing) enzymes are typically homodimeric proteins, meaning they consist of two identical subunits. Each subunit contains a copper ion that is essential for enzymatic activity. The copper ion is coordinated by histidine residues and other ligands within the active site. Additionally, these enzymes contain a cofactor known as topaquinone, which is derived from the post-translational modification of a tyrosine residue.

Function

The primary function of amine oxidase (copper-containing) enzymes is to catalyze the oxidative deamination of primary amines. This reaction involves the removal of an amine group from a substrate, resulting in the formation of an aldehyde, ammonia, and hydrogen peroxide. These enzymes are involved in various physiological processes, including the metabolism of biogenic amines such as histamine, serotonin, and dopamine.

Mechanism

The catalytic mechanism of amine oxidase (copper-containing) involves several steps:

1. The substrate binds to the active site, where it interacts with the copper ion and the topaquinone cofactor. 2. The amine group of the substrate is oxidized to an imine intermediate, with the reduction of the topaquinone to a semiquinone form. 3. The imine intermediate is hydrolyzed to release the corresponding aldehyde and ammonia. 4. The reduced topaquinone is reoxidized by molecular oxygen, producing hydrogen peroxide and regenerating the active form of the enzyme.

Biological Role

Amine oxidase (copper-containing) enzymes are found in a wide range of organisms, including bacteria, plants, and animals. In humans, these enzymes are involved in the regulation of neurotransmitter levels and the detoxification of xenobiotic amines. They also play a role in the cross-linking of collagen and elastin in the extracellular matrix, contributing to tissue structure and integrity.

Clinical Significance

Dysfunction or abnormal expression of amine oxidase (copper-containing) enzymes has been implicated in various diseases. For example, elevated activity of these enzymes can lead to increased production of hydrogen peroxide, contributing to oxidative stress and tissue damage. Inhibitors of amine oxidase (copper-containing) are being investigated as potential therapeutic agents for conditions such as depression, schizophrenia, and cardiovascular disease.

Related Pages

• Monoamine oxidase
• Flavin-containing monoamine oxidase
• Copper enzymes
• Biogenic amine

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