Biosynthesis of Pteridines in the Skin of the Tadpole, Rana cate8beiana

Biosynthesis of biopterin in the skin of the tadpole, Rana catesbeianawas investigated with guanosine-14C(U), neopterin-8a-14C, 7,8-dihydroneopterin- 8a-14C, neopterin-3'-phosphate-8a-14C and 7, 8-dihydro-2-amino- 4-hydroxypteridine-8a-14C. It was found that after incubating any of these compounds with tadpole skins radioactive biopterin could be isolated. Neopterin-3'-phosphate-8a-14C and 7,8-dihydroneopterin were both incorporated into biopterin more effectively than neopterin. Thus, it was postulated that dihydroneopterin-3'-phosphate or its pyrophosphate might be a direct precursor of biopterin.