2, TH) catalyzes the hydroxylation of tyrosine to 3,4 dihydroxyphenylalanine
(L DOPA) with the oxidation of tetrahydrobiopterin (BH4), and is the rate limiting reaction in the synthesis of dopamine, a precursor molecule for epinephrine and norepinephrine (Nagatsu et al.
2012), whose roles are probably involved with the formation of chitin-binding dihydroxyphenylalanine
residues and carbonate mineral formation, respectively.
It is due to deficiency of enzyme tyrosinase which is responsible for the hydroxylation of L-tyrosine to 3, 4, dihydroxyphenylalanine
(DOPA) and its subsequent oxidation to dopaquinone.
Derivation of urinary dopamine from plasma dihydroxyphenylalanine
Ozawa K, et at Translational incorporation of l-3,4- dihydroxyphenylalanine