Enables 6-pyruvoyltetrahydropterin synthase activity. Predicted to act upstream of or within tetrahydrobiopterin biosynthetic process. Predicted to be located in cytoplasm. Predicted to be active in mitochondrion. Human ortholog(s) of this gene implicated in BH4-deficient hyperphenylalaninemia A and phenylketonuria. Orthologous to human PTS (6-pyruvoyltetrahydropterin synthase). [provided by Alliance of Genome Resources, Apr 2022]