Inhibition of Sepiapterin Mediated Formation of Dihydrobiopterin and Chemical Redox Cycling by Sulfa Drugs

Sepiapterin reductase (SPR) catalyzes the reduction of sepiapterin to dihydrobiopterin (BH2), a precursor for tetrahydrobiopterin (BH4), a cofactor critical for nitric oxide biosynthesis and alkylglycerol and aromatic amino acid metabolism. SPR also mediates chemical redox cycling, catalyzing one electron reduction of redox active chemicals including quinones; rapid reaction of these radicals with molecular oxygen generates reactive oxygen...