Description
The reaction involves hydrolysis of two C-N bonds and isomerization of the pentose unit; the recyclization may be non-enzymic. This enzyme is involved in the de novo synthesis of tetrahydrobiopterin from GTP, with the other enzymes involved being EC 1.1.1.153 (sepiapterin reductase) and EC 4.2.3.12 (6-pyruvoyltetrahydropterin synthase)