Pteridine reductase () is an enzyme that catalyzes the chemical reaction
The substrates of this enzyme are biopterin, reduced nicotinamide adenine dinucleotide phosphate (NADPH), and two protons. Its products are tetrahydrobiopterin and oxidised NADP<sup>+</sup>. It was isolated from the parasite Leishmania major.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 5,6,7,8-tetrahydrobiopterin:NADP+ oxidoreductase. Other names in common use include PTR1, and pteridine reductase 1.
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , and .