Fig. 1.

PAH mutations covered in this work mapped onto the monomer of a composite model of full-length PAH. Orange represents the regulatory domain (1–142), gray represents the catalytic domain (143–410), and blue represents the oligomerization domain (411–452). The iron at the active site is displayed as a yellow sphere, whereas the tetrahydrobiopterin (BH₄), thienylalanine (TIH) substrate analog, and protein side chains are colored by individual atom colors (green is carbon, blue is nitrogen, red is oxygen, and yellow is sulfur). The purple regions are considered the pterin-binding regions.