In the second step, the L-dopa formed by tyrosine hydroxylation is quickly decarboxylated by another enzyme called aromatic L-amino acid decarboxylase (AADC), to the neurotransmitter dopamine.

在第二步中，由酪氨酸羟基化形成的L-多巴通过酶快速脱羧另一种称为芳香族L-氨基酸脱羧酶（AADC）的神经递质多巴胺。