Probing Inducible Nitric Oxide Synthase with a Pterin–Ruthenium(II) Sensitizer Wire

Nitric oxide synthase (NOS) is the primary biological source of the ubiquitous signaling molecule, nitric oxide (•NO). The enzyme utilizes tetrahydrobiopterin (H4B) as an essential cofactor, where it plays a key role in the catalytic conversion of L-arginine to citrulline and •NO.1 The pterin has been shown to serve both structural and catalytic roles in the enzyme by affecting the monomer to dimer transition, promoting protein stability, and forming a radical cation during catalytic turnover.2