Synthesis of biopterin from dihydroneopterin triphosphate by rat tissues.

High performance liquid chromatography procedure for the analysis of pterins of biopterin synthesis from dihydroneopterin triphosphate via sepiapterin in rat tissues has been described. Sepiapterin-synthesizing enzyme 1, which catalyzes in the presence of Mg2+ the conversion of dihydroneopterin triphosphate to an intermediate designated compound X was assayed by determining pterin which is formed from compound X under acidic conditions. Sepiapterin- and biopterin-synthesizing activity were also assayed by determining sepiapterin and biopterin, respectively. Analytical results revealed the presence of these activities in most rat tissues examined and high levels were found in kidney, pineal gland and liver. Activities were also detectable in peripheral erythrocytes.