In P. blakesleeanus , the main pterin was biopterin. I produces dihydroneopterin triphosphate from GTP, the precursor for the biosynthesis of pterins. The reduced pterins were detected after oxidation to fluorescent compounds. In P. blakesleeanus the total amounts of pterins were decreased and the level of GTP-cyclohydrolase I was also relative to those in N. crassa . Table 1 .
Values are means of three experiments.
In animals dihydroneopterin triphosphate is converted to 6-pyruvoyl tetrahydropterin, which is sequentially reduced by the action of sepiapterin reductase to yield tetrahydrobiopterin. The financial support of the Deutsche Forschungsgemeinschaft is acknowledged.