tyrosine 3-monooxygenase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: L-tyrosine + tetrahydrobiopterin + O2 = 3,4-dihydroxy-L-phenylalanine + 4-alpha-hydroxytetrahydrobiopterin + H2O. [EC:1.14.16.2]

Tyrosine 3-monooxygenase activity is a crucial enzymatic process that catalyzes the hydroxylation of the amino acid tyrosine to 3,4-dihydroxyphenylalanine (DOPA), the initial and rate-limiting step in the biosynthesis of catecholamines. These catecholamines, including dopamine, norepinephrine, and epinephrine, play vital roles as neurotransmitters, hormones, and signaling molecules in various physiological processes. The enzyme responsible for this activity, tyrosine hydroxylase (TH), is a monooxygenase that utilizes molecular oxygen and tetrahydrobiopterin (BH4) as cofactors. The reaction involves the insertion of an oxygen atom from molecular oxygen into the aromatic ring of tyrosine, forming DOPA. This process requires the binding of both tyrosine and BH4 to the enzyme's active site. TH undergoes a complex catalytic cycle involving multiple steps. First, the enzyme binds to both tyrosine and BH4. Then, molecular oxygen binds to the enzyme's iron atom, which is located in the active site. The oxygen molecule is activated and reacts with BH4, forming a reactive oxygen species. This activated oxygen species then reacts with tyrosine, resulting in the formation of DOPA and the regeneration of the oxidized form of BH4. The reaction is highly regulated by various factors, including substrate concentration, cofactor availability, and phosphorylation status. The activity of TH is also influenced by a range of regulatory proteins and signaling pathways. TH plays a critical role in regulating catecholamine synthesis and is a primary target for pharmacological intervention in conditions affecting catecholamine levels, such as Parkinson's disease and depression.'
"

Proteins (1)

Compounds (3)