MAPK3

Monoamine Oxidase B (MAO-B)

Monoamine Oxidase B (MAO-B) is an enzyme that plays a critical role in the metabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues. It is one of the two isoforms of monoamine oxidase, the other being MAO-A. MAO-B is primarily responsible for the oxidative deamination of dopamine and phenylethylamine, which are important neurotransmitters in the brain.

Structure and Function

MAO-B is a flavin-containing enzyme that is located in the outer mitochondrial membrane. It is encoded by the MAOB gene, which is located on the X chromosome. The enzyme is a homodimer, meaning it consists of two identical subunits, each containing a flavin adenine dinucleotide (FAD) cofactor that is essential for its catalytic activity.

MAO-B catalyzes the oxidative deamination of monoamines, converting them into their corresponding aldehydes, ammonia, and hydrogen peroxide. This reaction is crucial for the regulation of neurotransmitter levels in the brain, particularly dopamine, which is involved in motor control, motivation, and reward.

Clinical Significance

MAO-B has been implicated in several neurological disorders, most notably Parkinson's Disease. In Parkinson's disease, the degeneration of dopaminergic neurons leads to a decrease in dopamine levels. MAO-B inhibitors, such as Selegiline and Rasagiline, are used as therapeutic agents to increase dopamine availability by preventing its breakdown.

MAO-B activity also increases with age, which may contribute to age-related neurodegenerative processes. Elevated MAO-B levels have been associated with increased oxidative stress due to the production of hydrogen peroxide, a byproduct of the enzymatic reaction.

Inhibitors

MAO-B inhibitors are a class of drugs that selectively inhibit the activity of the enzyme, thereby increasing the levels of dopamine and other monoamines. These inhibitors are used in the treatment of Parkinson's disease and other conditions characterized by low dopamine levels.

Examples of MAO-B Inhibitors

• Selegiline
• Rasagiline
• Safinamide

Research and Development

Ongoing research is focused on developing more selective and potent MAO-B inhibitors with fewer side effects. Additionally, studies are exploring the role of MAO-B in other neurodegenerative diseases, such as Alzheimer's Disease, and its potential as a therapeutic target.

Also see

• Monoamine Oxidase A
• Dopamine
• Parkinson's Disease
• Neurotransmitter
• Oxidative Stress

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