The initial breakdown of catecholamines involves the enzymes
A) catechol-O-methyltransferase and tyrosine hydroxylase.
B) monoamine oxidase and homovanillic acid.
C) catechol-O-methyltransferase and monoamine oxidase.
D) monoamine oxidase and tyrosine hydroxylase.

Question

Quizplus · Accepted Answer

The initial breakdown of catecholamines involves the enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). COMT adds a methyl group to the catechol structure of dopamine, norepinephrine, and epinephrine, making them less reactive and more easily excreted by the body. MAO breaks down the aromatic ring structure of these neurotransmitters, further aiding in their elimination. Tyrosine hydroxylase is responsible for the synthesis of catecholamines, not their breakdown. Homovanillic acid is a metabolite of dopamine and not an enzyme involved in its breakdown.

The Initial Breakdown of Catecholamines Involves the Enzymes