| caption = Tyrosine hydroxylase catalyzes conversion of [[tyrosine]] to [[L-DOPA|<small>L</small>-DOPA]] using Fe<sup>2+</sup>, O<sub>2</sub> and BH<sub>4</sub> | | caption = Tyrosine hydroxylase catalyzes conversion of [[tyrosine]] to [[L-DOPA|<small>L</small>-DOPA]] using Fe<sup>2+</sup>, O<sub>2</sub> and BH<sub>4</sub> |