Sapropterin er en syntetisk udgave af det naturligt forekommende 6R- BH4, som er en cofaktor for fenylalanin -, tyrosin - og tryptophan hydroksylase.
Sapropterin is a synthetic version of the naturally occurring 6R-BH4, which is a cofactor of the hydroxylases for phenylalanine, tyrosine and tryptophan.